Islands and Protected Areas of the Gulf of California
Country
Mexico
Inscribed in
2005
Criteria
(vii)
(ix)
(x)
The conservation outlook for this site has been assessed as "critical" in the latest assessment cycle. Explore the Conservation Outlook Assessment for the site below. You have the option to access the summary, or the detailed assessment.
The site comprises 244 islands, islets and coastal areas that are located in the Gulf of California in north-eastern Mexico. The Sea of Cortez and its islands have been called a natural laboratory for the investigation of speciation. Moreover, almost all major oceanographic processes occurring in the planet’s oceans are present in the property, giving it extraordinary importance for study. The site is one of striking natural beauty in a dramatic setting formed by rugged islands with high cliffs and sandy beaches, which contrast with the brilliant reflection from the desert and the surrounding turquoise waters. It is home to 695 vascular plant species, more than in any marine and insular property on the World Heritage List. Equally exceptional is the number of fish species: 891, 90 of them endemic. The site, moreover, contains 39% of the world’s total number of species of marine mammals and a third of the world’s marine cetacean species. © UNESCO
Summary
2025 Conservation Outlook
Finalised on
11 Oct 2025
Critical
Current state and trend of VALUES
Critical
Overall THREATS
Overall PROTECTION and MANAGEMENT
Full assessment
Description of values
Striking natural beauty
Criterion
(vii)
This serial World Heritage site is of striking natural beauty and provides a dramatic setting due to the rugged forms of the desertic islands, with high cliffs and sandy beaches contrasting with the brilliant reflection from the desert and the surrounding turquoise waters. The diversity of forms and colours is complemented by a wealth of birds and marine life. The diversity and abundance of marine life associated to spectacular submarine forms and high water transparency makes the property a diver’s paradise particularly for the peninsular coast and islands as continental coast has mangroves, and estuaries (World Heritage Committee, 2013). The Gulf of California (GC) is an elongated water body (1200 km), with variable width (90–222 km), 40 coastal lagoons, and 922 islands and islets. Its extensive coastline and surroundings include a huge diversity of landscapes with streams, rivers, aquifers, wetlands, lagoons, marshes, swamps, salt flats, valleys, dunes and deserts.
A natural laboratory for the study of speciation and oceanographic processes
Criterion
(ix)
The site represents a unique example in which, in a very short distance, there are simultaneously “bridge islands” (populated by land in ocean level decline during glaciations) and oceanic islands (populated by sea and air). The elongated gulf has a sea current circulation with numerous eddies that help to connect biota from both coasts for species with planktonic life stages. Moreover, almost all major oceanographic processes occurring in the planet’s oceans are present in the site, giving it extraordinary importance for the study of marine and coastal processes. These processes are indeed supporting the high marine productivity and biodiversity richness that characterize the Gulf of California (World Heritage Committee, 2013). Intense Northwest winds during winter and spring cause coastal upwelling along the continental coast of the gulf, and weaker Southeast winds during summer and autumn cause coastal upwelling events along the peninsular coast of the gulf and the Midrift region has intense upwelling due tidal currents and abrupt changes in sea floor depth causing low temperatures and highly productive upwellings throughout the year (Lavin and Marinone, 2003).
Diversity of terrestrial and marine life
Criterion
(x)
The diversity of terrestrial and marine life in the property is extraordinary and constitutes a global priority for biodiversity conservation. On land, the close to 700 species of vascular plants are notable within a desert environment. There are 115 species of reptiles, almost half of them endemic, in some cases even to individual islands. 154 land bird species have been recorded and the property is of particular importance to migratory species. Over 900 species of fish have been documented with some 80 species occurring exclusively in the Gulf of California or parts of it. The World Heritage site provides habitat for about 35% of the world’s total number of cetacean species, including the smallest one, the critically endangered vaquita Phocoena sinus and the Totoaba Totoaba macdonaldi. In addition a large number of California sea lion colonies occur throughout the site with 13 breeding colonies. The endangered Blue Whale and Fin Whale (this species has a permanent population in the gulf) as well as the vulnerable Sperm Whale also visit the area.
Another notable species includes the Humpback Whale (Megaptera novaeangliae), listed under Mexican Official Standard 059 as subject to special protection. Sea turtles are a group for which significant conservation efforts are being carried out, and in the case of the olive ridley turtle (Lepidochelys olivacea), a very important population recovery has been recorded. Another species that is both emblematic and charismatic is the whale shark (Rhincodon typus), present along the coast of the peninsula and also in Nayarit; apparently, there is a migration of individuals between these points (Justification Study for declaring the Marine Zone of Isla Isabel as a Protected Area, 2023). Furthermore seabirds are very numerous, highly diverse, and important indicators of fish abundance throughout the property. In addition, the serial site includes a good sample of the Sonora desert ecosystems, considered one of the richest deserts in the world from the desert biodiversity point of view (World Heritage Committee, 2013).
The site includes, in addition to desert islands, islands where the tropical dry forest is well represented, such as Isla Isabel National Park and the Islas Marías Biosphere Reserve. Islas Marías constitute an area with rugged topography, with altitudes ranging from 100 to 660 meters above sea level (masl), presenting a wide representativity of ecosystems, including pelagic marine environments, coasts, reefs, mangroves, dry forests, scrublands, and coastal dunes that contain the genetic heritage of humanity. Islas Marías are a relict of the Mexican dry tropical biota that has remained isolated from the mainland for more than eight million years, and currently serve as a rich reservoir of wildlife taxa endemic to Mexico, such as the yellow-headed parrot of the Islas Marías (Amazona oratrix subsp. tresmarie) or the raccoon of Islas Marías (Procyon lotor subsp. insularis). Furthermore, there have been new species records, such as the hammerhead shark (Sphyrna zygaena), which would be the first sighting for the Reserve. There was also a record of a wild mouse of the genus Peromyscus, which is significant because it had not been recorded since 2006 (IUCN Consultation, 2025).
Another notable species includes the Humpback Whale (Megaptera novaeangliae), listed under Mexican Official Standard 059 as subject to special protection. Sea turtles are a group for which significant conservation efforts are being carried out, and in the case of the olive ridley turtle (Lepidochelys olivacea), a very important population recovery has been recorded. Another species that is both emblematic and charismatic is the whale shark (Rhincodon typus), present along the coast of the peninsula and also in Nayarit; apparently, there is a migration of individuals between these points (Justification Study for declaring the Marine Zone of Isla Isabel as a Protected Area, 2023). Furthermore seabirds are very numerous, highly diverse, and important indicators of fish abundance throughout the property. In addition, the serial site includes a good sample of the Sonora desert ecosystems, considered one of the richest deserts in the world from the desert biodiversity point of view (World Heritage Committee, 2013).
The site includes, in addition to desert islands, islands where the tropical dry forest is well represented, such as Isla Isabel National Park and the Islas Marías Biosphere Reserve. Islas Marías constitute an area with rugged topography, with altitudes ranging from 100 to 660 meters above sea level (masl), presenting a wide representativity of ecosystems, including pelagic marine environments, coasts, reefs, mangroves, dry forests, scrublands, and coastal dunes that contain the genetic heritage of humanity. Islas Marías are a relict of the Mexican dry tropical biota that has remained isolated from the mainland for more than eight million years, and currently serve as a rich reservoir of wildlife taxa endemic to Mexico, such as the yellow-headed parrot of the Islas Marías (Amazona oratrix subsp. tresmarie) or the raccoon of Islas Marías (Procyon lotor subsp. insularis). Furthermore, there have been new species records, such as the hammerhead shark (Sphyrna zygaena), which would be the first sighting for the Reserve. There was also a record of a wild mouse of the genus Peromyscus, which is significant because it had not been recorded since 2006 (IUCN Consultation, 2025).
Assessment information
The bycatch of the vaquita in illegal gillnets used to fish for totoaba is the sole factor leading to its status of being in immediate danger of extinction. The impact of bycatch on other marine species (i.e. other cetaceans, turtles, seals and shark as well as other fish species) has not been adequately assessed. The illegal fishing of totoaba also poses a very high threat to the values of the site, even though it is concentrated in the Upper Gulf. Another threat is pollution from fishing gear, microplastics and farm run-off, boat fuel, plastic flotsam and sewage. The introduction of invasive alien species presents another threat to native species and invasive alien species are known to be present on 10 islands, although of the 240 islands, 90% of these species were already present at the time of the site’s inscription on the World Heritage List. Recently Biosafety Protocols have been implemented and eradication efforts are underway e.g. for the black rat. Tourism and tourism-related infrastructure has also been problematic, mostly due to lack of compliance from tourism providers. Climate change poses an overall high threat but the impacts on the site's key attributes are not yet fully understood. Climate variability, El Niño events and ocean warming have already likely impacted endemic reptiles, rodents, seabird colonies, coral fauna and associated invertebrates and ichthyofauna. Annual monitoring of the density of micro-endemic reptiles and mammals on the islands shows changes associated with oceanographic phenomena such as El Niño or La Niña; however, statistically, no decreasing trend has been observed. Climate change has most likely a direct impact on the productivity of the Gulf of California, thereby also impacting the fish stocks.
Invasive Non-Native/ Alien Species
(Introduction of exotic species on islands)
Invasive/problematic species
Rattus rattus
Mus musculus
Felis catus
Canis lupus
Cenchrus ciliaris
Capra hircus
Tamarix aphylla
Mesembryanthemum crystallinum
Inside site
, Localised(<5%)
Outside site
A key threat for the native species of the islands is the introduction of exotic species such as cats, rats, and goats, which are set loose (or have been set loose in the past) on purpose or by negligence by people from tourist yachts or fishermen who camp on the islands. Many of the introductions of exotic species occurred as a result of guano extraction activities in the 19th century, while others have been more recent, such as the small patch of buffelgrass found in 2017 on San Pedro Mártir Island. These introductions can radically alter delicate island ecosystems (UNEP-WCMC, 2011; CONANP, 2006).
With respect to the islands of the APFF Gulf of California Islands off the coast of Sonora and the Isla San Pedro Mártir Biosphere Reserve (40 islands covering an area of 132,014.69 ha), invasive alien species are present on ten of them. However, they occupy only 1,263.66 ha, which represents just 0.96567% of the total surface area of these islands. Therefore, although it is a potentially serious concern, the issue currently affects a small percentage of the property’s surface (IUCN Consultation, 2025).
Monitoring results indicate the presence of exotic rodents (black rats and house mice) on five islands, cats and dogs on two islands, and buffelgrass, a highly invasive Old World grass, on three islands (IUCN Consultation, 2024). During 2022 to 2024, monitoring of exotic rodents (Rattus rattus and Mus musculus) was conducted on San Esteban, Dátil, Cholludo and Alcatraz islands. Based on the results, it was concluded that there are no new introductions. Of the four islands monitored, only two confirmed the presence of Rattus rattus on San Esteban Island and Mus musculus on Alcatraz Island (State Party of Mexico, 2025). On the islands off the state of Baja California Sur, goats and cats are present on Espiritu Santo. Goats and cats are also present on the islands of San José, Cerralvo, and San Marcos. Salt pine is present on Cerralvo Island; an effort to control it was made in 2010. On the islands off the state of Baja California, the presence of cats, ice pine, and salt pine have been recorded on Ángel de la Guarda Island, and black rats on Mejía Island. Control and monitoring efforts are ongoing.
In addition to these terrestrial species, at least 23 exotic marine species have established populations in the Gulf, two of which are considered invasive (the polychaete Branchiomma bairdi and the ascidian Polyclinum constellatum) (Tovar-Hernández et al., 2014). It is not known if any of these have become established on any of the Gulf islands in the property.
For several islands successful actions have been taken to eradicate and/or control alien or exotic species, as well as to conduct research on how to achieve eradication (UNESCO/IUCN, 2017). The black rat has been successfully eradicated in 2000 on San Jorge Island and in 2007 on San Pedro Mártir Island, now under the category of Biosphere Reserve (Samaniego et al., 2009) and actions have been implemented to control Buffel Grass, including the one carried out on San Pedro Mártir Island in 2019 (Torres et al., 2020). Rats were also eradicated from Isla Isabel, and as of 2025, the island remains free of these rodents (GECI annual report, 2011). The result of this eradication has been an increase in the number of bird species that temporarily visit the island (eBird bird list, 2024). On Farallón de San Ignacio Island, the removal of black rats was also successfully carried out. In 2014, on Venados Island, located in Mazatlán Bay, a goat population was eradicated from the island. From 2022 to 2024, on Venados Island in Mazatlán Bay, control actions were carried out for buffelgrass and carrizo. In the PNBL, activities were carried out to address exotic species, successfully eradicating (cats and goats) on four of the five islands. In coordination with GECI, actions have been carried out for goat control on the islands of Cleofas, Magdalena, and María Madre, and for cat and rat control on María Madre Island.
The systematic monitoring of rocky reefs that has been implemented annually for over 15 years in the Isla San Pedro Mártir Biosphere Reserve (RBISPM), covering approximately 73 fish species and 35 invertebrate species, has not reported the presence of invasive alien species.
More recently, Biosafety Protocols have been implemented for the visiting and floating population that enters the islands, consisting of the use of brushing and disinfection stations for footwear, as well as the disinfection of materials, vehicles, machinery and luggage, for the protection of the native flora and fauna of the insular territory (State Party of Mexico, 2024).
With respect to the islands of the APFF Gulf of California Islands off the coast of Sonora and the Isla San Pedro Mártir Biosphere Reserve (40 islands covering an area of 132,014.69 ha), invasive alien species are present on ten of them. However, they occupy only 1,263.66 ha, which represents just 0.96567% of the total surface area of these islands. Therefore, although it is a potentially serious concern, the issue currently affects a small percentage of the property’s surface (IUCN Consultation, 2025).
Monitoring results indicate the presence of exotic rodents (black rats and house mice) on five islands, cats and dogs on two islands, and buffelgrass, a highly invasive Old World grass, on three islands (IUCN Consultation, 2024). During 2022 to 2024, monitoring of exotic rodents (Rattus rattus and Mus musculus) was conducted on San Esteban, Dátil, Cholludo and Alcatraz islands. Based on the results, it was concluded that there are no new introductions. Of the four islands monitored, only two confirmed the presence of Rattus rattus on San Esteban Island and Mus musculus on Alcatraz Island (State Party of Mexico, 2025). On the islands off the state of Baja California Sur, goats and cats are present on Espiritu Santo. Goats and cats are also present on the islands of San José, Cerralvo, and San Marcos. Salt pine is present on Cerralvo Island; an effort to control it was made in 2010. On the islands off the state of Baja California, the presence of cats, ice pine, and salt pine have been recorded on Ángel de la Guarda Island, and black rats on Mejía Island. Control and monitoring efforts are ongoing.
In addition to these terrestrial species, at least 23 exotic marine species have established populations in the Gulf, two of which are considered invasive (the polychaete Branchiomma bairdi and the ascidian Polyclinum constellatum) (Tovar-Hernández et al., 2014). It is not known if any of these have become established on any of the Gulf islands in the property.
For several islands successful actions have been taken to eradicate and/or control alien or exotic species, as well as to conduct research on how to achieve eradication (UNESCO/IUCN, 2017). The black rat has been successfully eradicated in 2000 on San Jorge Island and in 2007 on San Pedro Mártir Island, now under the category of Biosphere Reserve (Samaniego et al., 2009) and actions have been implemented to control Buffel Grass, including the one carried out on San Pedro Mártir Island in 2019 (Torres et al., 2020). Rats were also eradicated from Isla Isabel, and as of 2025, the island remains free of these rodents (GECI annual report, 2011). The result of this eradication has been an increase in the number of bird species that temporarily visit the island (eBird bird list, 2024). On Farallón de San Ignacio Island, the removal of black rats was also successfully carried out. In 2014, on Venados Island, located in Mazatlán Bay, a goat population was eradicated from the island. From 2022 to 2024, on Venados Island in Mazatlán Bay, control actions were carried out for buffelgrass and carrizo. In the PNBL, activities were carried out to address exotic species, successfully eradicating (cats and goats) on four of the five islands. In coordination with GECI, actions have been carried out for goat control on the islands of Cleofas, Magdalena, and María Madre, and for cat and rat control on María Madre Island.
The systematic monitoring of rocky reefs that has been implemented annually for over 15 years in the Isla San Pedro Mártir Biosphere Reserve (RBISPM), covering approximately 73 fish species and 35 invertebrate species, has not reported the presence of invasive alien species.
More recently, Biosafety Protocols have been implemented for the visiting and floating population that enters the islands, consisting of the use of brushing and disinfection stations for footwear, as well as the disinfection of materials, vehicles, machinery and luggage, for the protection of the native flora and fauna of the insular territory (State Party of Mexico, 2024).
Recreational Activities
(Impacts from tourism)
Inside site
, Scattered(5-15%)
Outside site
Tourists and other visitors (including research scientists) can degrade island and coastal habitats, cause erosion, leave waste and litter, and disturb the breeding grounds of birds and sea lions. Looting of archaeological sites, deforestation of dunes and tree-felling also occurs (UNEP-WCMC, 2011). The threat from tourism has been minimal and localized, particularly in the area of human settlements along the coastal strip that borders the marine portion of the RB-AGCyDRC, toward the towns of San Felipe in Baja California and Golfo de Santa Clara in Sonora. However, it tends to increase toward the city and port of Puerto Peñasco, Sonora, in the area of influence outside the marine portion of the RB-AGCyDRC (IUCN Consultation, 2025).
Whale watching occurs in several areas and has the potential for disturbing cetaceans; however, this activity is carefully regulated and currently there are no indications of negative impacts (UNESCO/IUCN, 2017). Currently, the islands off the coast of Sonora do not experience significant impacts from tourism activities, as the rugged nature and remoteness of most of the islands in this region act as a natural barrier, preventing tourists from disembarking. There are only a few islands with relatively easy access, such as Tiburón Island (owned by the Comcaac People), which is visited for its scenic beauty and biological attributes. This island is considered one of the most intact ecosystems in the Sonoran Desert. Low-impact tourism activities are carried out on the island by tourism service providers from the Comcaac ethnic group, complying with current CONANP regulations. An Acceptable Change Limit study has also been conducted for the island (IUCN Consultation, 2024). Surveillance, monitoring, closed seasons, and compliance of regulations by tourism and industrial companies are important and have been implemented in a number of areas. Supervision and monitoring patrols have been carried out in coordination with other authorities with the aim of verifying that tourism activities are conducted in accordance with regulations. Additionally, tourism service providers have been trained to ensure their activities are compliant and minimize impacts on the island ecosystem. However, the application of environmental regulations is sometimes not enough for tourism service providers to comply with all standards (IUCN Consultation, 2024).
Isla Isabel National Park has had a Tourism Carrying Capacity since 2006 (year of publication of the Management Program), as well as trails that prevent people from entering important nesting areas, along with rules that visitors must follow. There have been no recorded impacts on seabird nesting colonies as a result of tourism activities (Isla Isabel National Park Management Program). The community-based companies that provide tourism services act as promoters of island conservation. These are primarily family-run community businesses that have taken steps to receive training, comply with environmental rules and regulations, and promote conservation among their clients (IUCN Consultation, 2025).
The RBIM currently has a Public Use Program, and work is being done on the tourism activity carrying capacity for María Madre Island, as well as for diving and snorkelling activities in the buffer zone of María Madre Island (IUCN Consultation, 2025).
Whale watching occurs in several areas and has the potential for disturbing cetaceans; however, this activity is carefully regulated and currently there are no indications of negative impacts (UNESCO/IUCN, 2017). Currently, the islands off the coast of Sonora do not experience significant impacts from tourism activities, as the rugged nature and remoteness of most of the islands in this region act as a natural barrier, preventing tourists from disembarking. There are only a few islands with relatively easy access, such as Tiburón Island (owned by the Comcaac People), which is visited for its scenic beauty and biological attributes. This island is considered one of the most intact ecosystems in the Sonoran Desert. Low-impact tourism activities are carried out on the island by tourism service providers from the Comcaac ethnic group, complying with current CONANP regulations. An Acceptable Change Limit study has also been conducted for the island (IUCN Consultation, 2024). Surveillance, monitoring, closed seasons, and compliance of regulations by tourism and industrial companies are important and have been implemented in a number of areas. Supervision and monitoring patrols have been carried out in coordination with other authorities with the aim of verifying that tourism activities are conducted in accordance with regulations. Additionally, tourism service providers have been trained to ensure their activities are compliant and minimize impacts on the island ecosystem. However, the application of environmental regulations is sometimes not enough for tourism service providers to comply with all standards (IUCN Consultation, 2024).
Isla Isabel National Park has had a Tourism Carrying Capacity since 2006 (year of publication of the Management Program), as well as trails that prevent people from entering important nesting areas, along with rules that visitors must follow. There have been no recorded impacts on seabird nesting colonies as a result of tourism activities (Isla Isabel National Park Management Program). The community-based companies that provide tourism services act as promoters of island conservation. These are primarily family-run community businesses that have taken steps to receive training, comply with environmental rules and regulations, and promote conservation among their clients (IUCN Consultation, 2025).
The RBIM currently has a Public Use Program, and work is being done on the tourism activity carrying capacity for María Madre Island, as well as for diving and snorkelling activities in the buffer zone of María Madre Island (IUCN Consultation, 2025).
Marine & Freshwater Aquaculture
(Shrimp farming)
Inside site
, Localised(<5%)
Shrimp aquaculture in the Gulf of California began expanding rapidly in the mid-1980s and has become a major economic activity, making the region the second largest shrimp producer in the western hemisphere. However, this issue is not widespread across all the islands included in the property. There is no current record of this threat in the marine portion of the RB-AGCyDRC and no threat in the PNBL. In the case of Isla Isabel, there are no recorded effects on the marine ecosystem surrounding the island caused by shrimp farms on the coast of Nayarit (IUCN Consultation, 2025).
In the region however, the expansion of shrimp ponds has caused significant loss of critical coastal habitats such as mangroves and salt marshes, which serve as nurseries and feeding grounds for diverse marine and bird species. The continual development of shrimp farming, in conjunction with municipal and agriculture effluents has raised concerns about: a) depletion of fish stocks, b) reduction of mangrove forest, c) frequent harmful algal blooms in coastal waters and shrimp ponds, and d) water quality deterioration (Páez-Osuna et al., 2003). Although a study by Barraza-Guardado et al. (2013) indicates that the material load in shrimp farm effluents in Bahía de Kino (not part of the property) change biogeochemic processes and the health of the coastal ecosystem, water quality data from the Isla San Pedro Mártir Biosphere Reserve, which is part of the serial property, show that there are no issues with water quality at the site (IUCN Consultation, 2025).
Other problems associated with shrimp farming are hypoxia and anoxia: Organic matter discharged by shrimp farms increases biochemical oxygen demand, leading to hypoxic conditions especially during warmer months or periods of low water circulation. This negatively affects benthic fauna and overall aquatic health. Shrimp farming may also cause disease and pathogen spread: Shrimp farms can act as sources of pathogens that may spread to wild populations, further threatening ecosystem health. Synergistic stressors cause combined effects of shrimp farm effluents and other activities like dredging exacerbate environmental stress by further reducing dissolved oxygen and increasing toxic nitrogen compounds, amplifying risks to coastal ecosystems (Barraza-Guardado et al., 2013, 2014; Cardoso-Mohedano et al., 2016).
Further assessment of the impact under consideration is needed to reliably assess the threat level to the key attributes of the property.
In the region however, the expansion of shrimp ponds has caused significant loss of critical coastal habitats such as mangroves and salt marshes, which serve as nurseries and feeding grounds for diverse marine and bird species. The continual development of shrimp farming, in conjunction with municipal and agriculture effluents has raised concerns about: a) depletion of fish stocks, b) reduction of mangrove forest, c) frequent harmful algal blooms in coastal waters and shrimp ponds, and d) water quality deterioration (Páez-Osuna et al., 2003). Although a study by Barraza-Guardado et al. (2013) indicates that the material load in shrimp farm effluents in Bahía de Kino (not part of the property) change biogeochemic processes and the health of the coastal ecosystem, water quality data from the Isla San Pedro Mártir Biosphere Reserve, which is part of the serial property, show that there are no issues with water quality at the site (IUCN Consultation, 2025).
Other problems associated with shrimp farming are hypoxia and anoxia: Organic matter discharged by shrimp farms increases biochemical oxygen demand, leading to hypoxic conditions especially during warmer months or periods of low water circulation. This negatively affects benthic fauna and overall aquatic health. Shrimp farming may also cause disease and pathogen spread: Shrimp farms can act as sources of pathogens that may spread to wild populations, further threatening ecosystem health. Synergistic stressors cause combined effects of shrimp farm effluents and other activities like dredging exacerbate environmental stress by further reducing dissolved oxygen and increasing toxic nitrogen compounds, amplifying risks to coastal ecosystems (Barraza-Guardado et al., 2013, 2014; Cardoso-Mohedano et al., 2016).
Further assessment of the impact under consideration is needed to reliably assess the threat level to the key attributes of the property.
Water-borne & other effluent Pollution
(Effluent pollution)
Inside site
, Scattered(5-15%)
Outside site
Pollution from farm run-off, boat fuel, plastic flotsam and sewage are on the increase in the Gulf and are expected to get much worse as tourism development continues around the region (UNEP-WCMC, 2011; Bath and Putney, 2010) and as the human population density increases. In comparison to other regions of the world, the pollution levels in the Gulf of California remain relatively low to moderate. However, contamination hotspots are found for metals and metalloids, in sites where mining spills have occurred and for nutrients and pesticides, in wetlands that receive discharges from intensive agricultural and shrimp farming. Locally pollution can be very high, such as in coastal lagoons in Sinaloa (Orduña-Rojas and Longoria-Espinoza, 2006), and Guaymas Bay (Ortiz-Lozano et al., 2005). It is known that every week the discharge from ships is dumped directly into the sea (IUCN Consultation, 2024). There are still numerous coastal environments in the Gulf of California where the scope of pollution sources and events have been poorly studied (Páez-Osuna et al., 2017).
Recreation & Tourism Areas
(Tourism infrastructure development)
Inside site
, Localised(<5%)
Analysis by WWF indicated that urban and tourist development in the Gulf posed a major threat to the region in the past (Cisneros-Mata, 2010). The construction of ill-conceived large-scale tourism resorts can overburden the ecosystems and natural resources, such as fresh water supply, local communities depend upon. Regarding the 35 islands of the APFF Gulf of California Islands off the coast of Sonora, listed in Annex I (List of Reef, Barren Isles and Rock), supervision and monitoring visits confirm that there are no infrastructure developments for tourism. Based on their geomorphological characteristics, the islands located off the coast of Sonora are arid and rugged, with irregularly shaped, steep coastlines and cliffs of varying heights; their beaches are rocky (SEMARNAT 2000; IUCN Consultation, 2024).
However, infrastructure built without prior development of studies, opening of material banks and the arrival of new vehicles on the island could represent a threat to habitats and species such as rabbits, snakes and iguanas, due to their vulnerability to being run over (IUCN Consultation, 2024). The current situation is varied across the component parts. Coastal development in the area of influence of the PNBL is growing, which may pose a potential threat to the protected area (IUCN Consultation, 2025). On Coronados Island, there is minimal infrastructure for managing tourism activity, which does not constitute a threat. An exception is Carmen Island, where there is a Wildlife Management Unit (UMA) for bighorn sheep, which includes infrastructure and potential for development.
In the Islas Marietas National Park, the terrestrial zone is a core zone and tourism activities are not allowed. There is no tourism infrastructure, only marine delimitation for swimming areas and mooring buoys. Similarly, Isla Isabel, due to its distance from the mainland and the absence of major urban and tourism development centers in its area of influence, does not face this issue (IUCN Consultation, 2025).
However, infrastructure built without prior development of studies, opening of material banks and the arrival of new vehicles on the island could represent a threat to habitats and species such as rabbits, snakes and iguanas, due to their vulnerability to being run over (IUCN Consultation, 2024). The current situation is varied across the component parts. Coastal development in the area of influence of the PNBL is growing, which may pose a potential threat to the protected area (IUCN Consultation, 2025). On Coronados Island, there is minimal infrastructure for managing tourism activity, which does not constitute a threat. An exception is Carmen Island, where there is a Wildlife Management Unit (UMA) for bighorn sheep, which includes infrastructure and potential for development.
In the Islas Marietas National Park, the terrestrial zone is a core zone and tourism activities are not allowed. There is no tourism infrastructure, only marine delimitation for swimming areas and mooring buoys. Similarly, Isla Isabel, due to its distance from the mainland and the absence of major urban and tourism development centers in its area of influence, does not face this issue (IUCN Consultation, 2025).
Fishing, Harvesting & Controlling Aquatic Species
(Bycatch of non-target species)
Inside site
, Scattered(5-15%)
Outside site
Bycatch and entanglement of non-target marine species in fishing gear can pose a major threat to local wildlife. Bycatch occurs mainly in gillnet fishery which causes mortality of small cetaceans such as dolphins and the vaquita, larger whales such as the Bryde’s whale, seals, turtles, sharks as well as other non-target fish. The illegal gillnet fishery in the Upper Gulf of California has been identified as the main cause for the high extinction risk of the vaquita (Rojas-Bracho and Reeves, 2013; UNESCO/IUCN, 2017, UNESCO/IUCN, 2018; Jaramillo-Legorreta et al., 2023). Gillnets are used by the illegal totoaba fishery, but also by the regulated curvina golfina and shrimp fisheries (UNESCO/IUCN, 2018). For the regulated fisheries, measures have been undertaken to develop alternative gears, which would not cause entanglement of the vaquita and other bycatch species (State Party of Mexico, 2018, 2019, 2020); however, progress with the introduction of new solutions has been slow. Due to the fishing methods used in the marine portion of the RB-AGCyDRC, the levels of bycatch of non-target species are minimal. Verification sources for this include the landing reports of the fisheries of the Upper Gulf of California, which are part of the information corresponding to the responsibilities of CONAPESCA.
Illegal fishing for totoaba also remains a very serious threat which is ongoing with an apparent reduction of enforcement agency activity thus significantly increasing this risk to vaquita (IWC 2024). There are also efforts to detect and remove illegal and derelict fishing gear found in the Vaquita Refuge and the Zero Tolerance Area (State Party of Mexico, 2025) along with a Blocking Project to discourage and prevent the setting of gillnets in the area. Several studies have argued that artisanal overfishing is a significant human impact on biota of the Gulf of California (Saenz-Arroyo et al., 2005; Alvarez-Romero et al., 2013; Wilder et al., 2025).
In January 2024, the marine zone surrounding Isla Isabel was designated as a Protected Natural Area, covering a surface of 30,000 hectares. The Management Program is currently under development, and one of its objectives related to fishing is to regulate shrimp trawling activities in order to reduce the chronic impact that this type of fishing has on the ecosystem and on fish populations considered bycatch (Official Gazette of the Federation, 2024).
Illegal fishing for totoaba also remains a very serious threat which is ongoing with an apparent reduction of enforcement agency activity thus significantly increasing this risk to vaquita (IWC 2024). There are also efforts to detect and remove illegal and derelict fishing gear found in the Vaquita Refuge and the Zero Tolerance Area (State Party of Mexico, 2025) along with a Blocking Project to discourage and prevent the setting of gillnets in the area. Several studies have argued that artisanal overfishing is a significant human impact on biota of the Gulf of California (Saenz-Arroyo et al., 2005; Alvarez-Romero et al., 2013; Wilder et al., 2025).
In January 2024, the marine zone surrounding Isla Isabel was designated as a Protected Natural Area, covering a surface of 30,000 hectares. The Management Program is currently under development, and one of its objectives related to fishing is to regulate shrimp trawling activities in order to reduce the chronic impact that this type of fishing has on the ecosystem and on fish populations considered bycatch (Official Gazette of the Federation, 2024).
Fishing, Harvesting & Controlling Aquatic Species
(Over-fishing)
Inside site
, Widespread(15-50%)
Outside site
Over-fishing of marine resources can occur from both artisanal and industrial fishing. Trawling, shrimp trawling, the use of line and depth seines and harpoons and the (illegal) overfishing of commercially important and endangered species such as the totoaba, are contributing to the gradual degradation of this rich sea. Historically, over 85 percent of the Gulf’s fisheries were either at their maximum sustainable yield or overexploited (Cisneros-Mata, 2010) highlighting the urgent need to enhance law enforcement and monitoring efforts. Some representative fisheries of the Upper Gulf of California, such as the gulf corvina fishery, which is authorized through quotas, have shown some trends of quota overruns in recent years. For most other fisheries, such as finfish, which are governed by mechanisms other than quotas, catch levels have remained stable (IUCN Consultation, 2025).
A study (Arreguin-Sanchez et al., 2017) concludes that most of the observed changes in fish stocks are also strongly linked to climate effects. They recommend that management measures for fishery should be guided by an adaptive strategy in which harvest rates are consistent with year-to-year biomass availability and ecosystem dynamics. From April 2023 to September 2024, 29 administrative resolutions were issued to classify fishing violations, resulting in the imposition of fines for a total amount of MXN 1,494,374.7 (MXN 425,437.74 during 2023 and MXN 1,068,936.96 during 2024), and the seizure of goods associated with illegal activities, including 44 gillnets that together totalled more than 11,200 meters in length (State Party of Mexico, 2024).
Since 2014, there have been agreements with fishers on Isla Isabel for the marine conservation of a strip surrounding the island where rocky-coral reefs are located. Currently, with the decree of the marine Protected Natural Area published in 2024 and the Management Program being developed, legal grounds will be established for reef zones, rocky bottoms, and other habitats important for marine and fisheries productivity. Additionally, since 2014, support has been provided to the island's fishers to form a cooperative for the legal harvesting of lobsters under a sustainable management program (Biological and fisheries study for lobster harvesting, 2014).
It is also known that IMIPAS is evaluating a Technical Justification Study for the establishment of a Fish Refuge off the coast of the state of Nayarit. Fish refuges are initiatives led by the fishing sector to conserve and manage areas of importance for commercial species (NOM-049-Fish Refuges, 2014).
A radar was installed on María Madre Island to monitor illegal fishing in the northern part of the RBIM (IUCN Consultation, 2025).
Overall, the occurrence of this threat tends to take place both within the marine portion of the Upper Gulf of California and Colorado River Delta Biosphere Reserve (RB-AGCyDRC) and outside of it, including in other components of the serial World Heritage property. In the case of the Upper Gulf of California, from January to June—coinciding with the northward migration of the totoaba for spawning—the incidence of this threat tends to increase. This trend reverses during the rest of the year when the species migrates southward along the peninsular coastline of the Gulf of California, where the threat correspondingly intensifies in those areas and property components.
Although illegal fishing and overexploitation of fisheries are threats throughout the Gulf, in marine protected areas, efforts are being promoted to regulate fishing activities through fishery management programs, best fishing practices, the establishment of fish refuges, among others; all these processes involve the participation of individual fishers as well as large and small fishing organizations (IUCN Consultation, 2025). Fishing regulations in the Upper Gulf of California have been updated—particularly since the entry into force of the regulatory agreement published in the Official Gazette on 09/24/2020 (Agreement regulating gear, systems, methods, techniques, and schedules for fishing activities with small and large vessels in Mexican Marine Zones in the Northern Gulf of California, and establishing landing sites as well as the use of monitoring systems for such vessels)—with the creation of the zero-tolerance zone and the subsequent placement of concrete blocks with hooks to secure part of the vaquita refuge area as gillnet-free, there has been some containment of this threat. However, inspection and surveillance of fishing activities remain a challenge in order to prevent illegal practices, such as the use of prohibited gillnets, from continuing to put priority species at risk.
A study (Arreguin-Sanchez et al., 2017) concludes that most of the observed changes in fish stocks are also strongly linked to climate effects. They recommend that management measures for fishery should be guided by an adaptive strategy in which harvest rates are consistent with year-to-year biomass availability and ecosystem dynamics. From April 2023 to September 2024, 29 administrative resolutions were issued to classify fishing violations, resulting in the imposition of fines for a total amount of MXN 1,494,374.7 (MXN 425,437.74 during 2023 and MXN 1,068,936.96 during 2024), and the seizure of goods associated with illegal activities, including 44 gillnets that together totalled more than 11,200 meters in length (State Party of Mexico, 2024).
Since 2014, there have been agreements with fishers on Isla Isabel for the marine conservation of a strip surrounding the island where rocky-coral reefs are located. Currently, with the decree of the marine Protected Natural Area published in 2024 and the Management Program being developed, legal grounds will be established for reef zones, rocky bottoms, and other habitats important for marine and fisheries productivity. Additionally, since 2014, support has been provided to the island's fishers to form a cooperative for the legal harvesting of lobsters under a sustainable management program (Biological and fisheries study for lobster harvesting, 2014).
It is also known that IMIPAS is evaluating a Technical Justification Study for the establishment of a Fish Refuge off the coast of the state of Nayarit. Fish refuges are initiatives led by the fishing sector to conserve and manage areas of importance for commercial species (NOM-049-Fish Refuges, 2014).
A radar was installed on María Madre Island to monitor illegal fishing in the northern part of the RBIM (IUCN Consultation, 2025).
Overall, the occurrence of this threat tends to take place both within the marine portion of the Upper Gulf of California and Colorado River Delta Biosphere Reserve (RB-AGCyDRC) and outside of it, including in other components of the serial World Heritage property. In the case of the Upper Gulf of California, from January to June—coinciding with the northward migration of the totoaba for spawning—the incidence of this threat tends to increase. This trend reverses during the rest of the year when the species migrates southward along the peninsular coastline of the Gulf of California, where the threat correspondingly intensifies in those areas and property components.
Although illegal fishing and overexploitation of fisheries are threats throughout the Gulf, in marine protected areas, efforts are being promoted to regulate fishing activities through fishery management programs, best fishing practices, the establishment of fish refuges, among others; all these processes involve the participation of individual fishers as well as large and small fishing organizations (IUCN Consultation, 2025). Fishing regulations in the Upper Gulf of California have been updated—particularly since the entry into force of the regulatory agreement published in the Official Gazette on 09/24/2020 (Agreement regulating gear, systems, methods, techniques, and schedules for fishing activities with small and large vessels in Mexican Marine Zones in the Northern Gulf of California, and establishing landing sites as well as the use of monitoring systems for such vessels)—with the creation of the zero-tolerance zone and the subsequent placement of concrete blocks with hooks to secure part of the vaquita refuge area as gillnet-free, there has been some containment of this threat. However, inspection and surveillance of fishing activities remain a challenge in order to prevent illegal practices, such as the use of prohibited gillnets, from continuing to put priority species at risk.
Garbage & Solid Waste
(Plastics and microplastics)
Inside site
, Extent of threat not known
An increasingly pressing issue has to do with plastic waste, which decomposes to form the so-called microplastics, which affect marine life. CONANP and other authorities, in alliance with diverse organizations and local institutions, as well as with the Community Brigades, permanently carry out actions to clean up marine ecosystems, where efforts are directed towards the detection, recovery and eventual destruction of the so-called ghost nets, as well as the collection of solid waste on the seabed, beaches and wetlands (State Party of Mexico, 2025). CONANP carries out environmental education and outreach activities to promote awareness of the impact of plastics and microplastics in the ocean. With the support of Pronatura Noroeste A.C., the educational guide “For a Sea Free of Plastics” was developed and is distributed in the areas of influence of Isla Isabel National Park, the Islas Marías Biosphere Reserve, and Islas Marietas National Park, as well as in coastal communities of Northwestern Mexico. Additionally, in the case of Islas Marietas, the use of single-use plastics is prohibited. There is a waste management problem, with dumps located within María Madre Island. Work is being carried out in coordination with SEMAR to remove these dumps (IUCN Consultation, 2025).
Although the global generation of plastics and microplastics continues to rise, there are still no updated quantification mechanisms applicable to the marine portion of the RB-AGCyDRC. Nevertheless, the population growth of nearby human settlements has been contained, with little change in consumption habits due to economies slowed by the effects of global crises, generating the perception that the threat may be developing with moderate scope at present.
Although the global generation of plastics and microplastics continues to rise, there are still no updated quantification mechanisms applicable to the marine portion of the RB-AGCyDRC. Nevertheless, the population growth of nearby human settlements has been contained, with little change in consumption habits due to economies slowed by the effects of global crises, generating the perception that the threat may be developing with moderate scope at present.
Changes in Physical & Chemical Regimes, Changes in Temperature Regimes, Changes in Precipitation & Hydrological Regime
(Climate change)
Inside site
, Throughout(>50%)
Outside site
By 2050, climate change is expected to increase temperatures by 2 ºC, and decrease rainfall by 20% with high variability from season to season and year to year. Climate change is also expected to impact the local communities. At this point it seems that climate and climate change are an important, but not completely understood (Arreguin-Sanchez et al., 2017) source of variation that should be incorporated, together with ecosystem information, within scientific advice for management (i.e. fishery).
Fluctuations in island population densities of endemic reptiles and rodents could be directly and indirectly related to climate variability events (e.g., El Niño/climate change events), however, the densities recorded are within the threshold of natural variations recorded over more than 10 years of monitoring (State Party of Mexico, 2025). Climate variability may also be a cause of colony size reduction in three species of seabirds monitored on San Pedro Martir Island (blue-footed boobies, brown-footed boobies and brown pelicans) (e.g., El Niño/climate change events).
In 2023, the combination of the El Niño weather phenomenon, atmospheric warming resulting from the eruption of an underwater volcano in Tonga-Oceania, and climate change, resulted in the warmest year on record. Among the consequences of this situation, there is a notable rise in ocean temperatures in the American tropical Pacific, and severe coral bleaching on reefs from Colombia to Mexico (in the southern Gulf of California). The warming of the sea due to the El Niño event of 2023 had a great impact on the coral fauna and associated invertebrates, causing decreases in most of the functional indicators and environmental services. However, long-term monitoring studies conducted by Dr. Héctor Reyes (UABC) in Cabo Pulmo and Espíritu Santo show that, although oceanographic phenomena such as El Niño, the Pacific Decadal Oscillation, and the 2023 ocean warming event (linked to a volcanic eruption) caused temperature variations and population changes—including a coral bleaching episode in Cabo Pulmo—subsequent surveys documented the recovery of the reefs just a few months after the event (unpublished reports).
On the other hand, the ichthyofauna also presented modifications in abundance and specific composition, which lowered its value as an ecosystem provider of social services, although functional diversity remained stable. The data show that the area's communities have limited resilience capacity, so it was recommended that in the year 2024, efforts should be made to control the level of use of the reefs, to allow the communities to better respond to the damage suffered (State Party of Mexico, 2025).
Effects of climatic change on benthic biota have shown signs of tropicalization in the southwestern region of the Gulf of California (Favoretto et al., 2022) but this effect changes widely depending on the type of biota and the region of the gulf (Wilder et al., 2025; Paez-osuna et al., 2016).
Fluctuations in island population densities of endemic reptiles and rodents could be directly and indirectly related to climate variability events (e.g., El Niño/climate change events), however, the densities recorded are within the threshold of natural variations recorded over more than 10 years of monitoring (State Party of Mexico, 2025). Climate variability may also be a cause of colony size reduction in three species of seabirds monitored on San Pedro Martir Island (blue-footed boobies, brown-footed boobies and brown pelicans) (e.g., El Niño/climate change events).
In 2023, the combination of the El Niño weather phenomenon, atmospheric warming resulting from the eruption of an underwater volcano in Tonga-Oceania, and climate change, resulted in the warmest year on record. Among the consequences of this situation, there is a notable rise in ocean temperatures in the American tropical Pacific, and severe coral bleaching on reefs from Colombia to Mexico (in the southern Gulf of California). The warming of the sea due to the El Niño event of 2023 had a great impact on the coral fauna and associated invertebrates, causing decreases in most of the functional indicators and environmental services. However, long-term monitoring studies conducted by Dr. Héctor Reyes (UABC) in Cabo Pulmo and Espíritu Santo show that, although oceanographic phenomena such as El Niño, the Pacific Decadal Oscillation, and the 2023 ocean warming event (linked to a volcanic eruption) caused temperature variations and population changes—including a coral bleaching episode in Cabo Pulmo—subsequent surveys documented the recovery of the reefs just a few months after the event (unpublished reports).
On the other hand, the ichthyofauna also presented modifications in abundance and specific composition, which lowered its value as an ecosystem provider of social services, although functional diversity remained stable. The data show that the area's communities have limited resilience capacity, so it was recommended that in the year 2024, efforts should be made to control the level of use of the reefs, to allow the communities to better respond to the damage suffered (State Party of Mexico, 2025).
Effects of climatic change on benthic biota have shown signs of tropicalization in the southwestern region of the Gulf of California (Favoretto et al., 2022) but this effect changes widely depending on the type of biota and the region of the gulf (Wilder et al., 2025; Paez-osuna et al., 2016).
The lack of collaboration from tourism stakeholders may lead to unregulated mass tourism in the future which would threaten the ecosystem due to conflicting views on the future of the property. The establishment of a totoaba captive-breeding facility and the trade of products from this facility may mask the illegal trade of the totoaba swim bladders and inhibit effective law enforcement.
Marine & Freshwater Aquaculture
(Masking illegal activities which over-exploit fish resources and pose a high risk of bycatch of the critically endangered vaquita)
Inside site
, Extent of threat not known
The establishment of a totoaba captive-breeding facility and the trade of products from this facility may mask the illegal trade of the totoaba swim bladders and inhibit effective law enforcement.
Recreational Activities
(Mass tourism)
Inside site
, Widespread(15-50%)
Mass tourism in the Gulf of California is a potential threat to the region's ecosystems and biodiversity. Rapid tourism development, including mega-resort projects, poses serious risks to coastal and marine environments, particularly in Puerto Peñasco, Guaymas, Mazatlan, La Paz and Los Cabos.
The lack of collaboration from other institutions involved in activities within the island, coupled with the lack of prior consultations on the use of resources in the area, may favour mass tourism that causes greater impacts on the ecosystem i.e. if tourism service providers represent a vision that is far removed from the objective of Public Use of the island, it can have a negative effect on conservation (IUCN Consultation, 2024). This is considered a threat with rising visitation in some component parts e.g. the number of tourists visiting Cabo Pulmo National Park has increased considerably, from 2009 to 2024. In 2009, a total of 4,601 tourists visited the park; by 2023, there were 32,486 tourists, which is equivalent to a 706% increase. As of September 2024, there were 20,448 visitors (State Party of Mexico, 2025). Islands are protected and therefore it is not permissible to develop touristic infrastructure in the area. On María Madre Island, the company TURRIMAR currently carries out low-impact tourism activities; however, they intend to open up to mass tourism (IUCN Consultation, 2025)
On Isla Isabel, there is a tourism carrying capacity limit and rules for carrying out activities, so tourism does not pose a threat to the conservation of the island and marine ecosystems. In fact, tourist groups participate in environmental education and reef restoration activities in areas affected by the El Niño phenomenon. This may present a good practice example for other islands.
Within this controlled and regulated tourism framework, since the year 2000, some interested fishers have been encouraged to adopt tourism service provision as an activity and to form family-run tourism businesses as a strategy to reduce pressure on fishery resources. In this regard, as has been demonstrated in some protected natural areas, tourism development becomes a real alternative for the economy of people who are allies in conservation and also an alternative source for funding the operation and management of protected areas and for strengthening conservation projects (IUCN Consultation, 2025).
The lack of collaboration from other institutions involved in activities within the island, coupled with the lack of prior consultations on the use of resources in the area, may favour mass tourism that causes greater impacts on the ecosystem i.e. if tourism service providers represent a vision that is far removed from the objective of Public Use of the island, it can have a negative effect on conservation (IUCN Consultation, 2024). This is considered a threat with rising visitation in some component parts e.g. the number of tourists visiting Cabo Pulmo National Park has increased considerably, from 2009 to 2024. In 2009, a total of 4,601 tourists visited the park; by 2023, there were 32,486 tourists, which is equivalent to a 706% increase. As of September 2024, there were 20,448 visitors (State Party of Mexico, 2025). Islands are protected and therefore it is not permissible to develop touristic infrastructure in the area. On María Madre Island, the company TURRIMAR currently carries out low-impact tourism activities; however, they intend to open up to mass tourism (IUCN Consultation, 2025)
On Isla Isabel, there is a tourism carrying capacity limit and rules for carrying out activities, so tourism does not pose a threat to the conservation of the island and marine ecosystems. In fact, tourist groups participate in environmental education and reef restoration activities in areas affected by the El Niño phenomenon. This may present a good practice example for other islands.
Within this controlled and regulated tourism framework, since the year 2000, some interested fishers have been encouraged to adopt tourism service provision as an activity and to form family-run tourism businesses as a strategy to reduce pressure on fishery resources. In this regard, as has been demonstrated in some protected natural areas, tourism development becomes a real alternative for the economy of people who are allies in conservation and also an alternative source for funding the operation and management of protected areas and for strengthening conservation projects (IUCN Consultation, 2025).
Involvement of stakeholders and rightsholders, including indigenous peoples and local communities, in decision-making processes
The National Commission for Protected Areas (CONANP) works closely with local communities to develop livelihoods that are compatible with conservation. Years of working with the communities has led to generally good relations and a number of highly successful programmes have been developed, including monitoring and restoration programmes with participation of local communities (UNESCO/IUCN, 2017; State Party of Mexico, 2020, 2025).
Efforts carried out by CONANP in coordination with local community groups that benefit from subsidy programs, include both PROREST (Program for the Protection and Restoration of Ecosystems and Priority Species) and PROCODES (Conservation Program for Sustainable Development). These programs enable local participation in conservation, protection, restoration, and biodiversity monitoring actions within the marine portion of this component of the World Heritage property; and on the other, in community participation in sustainable development projects that guide users toward better economic practices in the use and management of natural resources.
In the case of PROREST-supported actions, young people from San Felipe, Baja California, participate in visual identification of vaquita and marine mammals through a training and equipment process aimed at building local capacity to increase available data on visual monitoring of the vaquita. Additionally, fishers participate in acoustic monitoring activities, given their extensive experience in deploying and replacing acoustic detectors that identify vaquita echolocation clicks, which helps guide visual monitoring efforts within the vaquita refuge area. Furthermore, fishers from that locality, as well as from Golfo de Santa Clara, Sonora, have participated in ghost net removal activities, known as “grampineo,” in the vaquita's habitat and adjacent zones (State Party of Mexico, 2025). On another front, community groups contribute to the collection, deactivation, shredding, and transformation of ghost nets or nets seized by authorities. Once shredded, these nets generate plastic waste that is repurposed by the community group using 3D printing and resins to create sculptures, keychains, and various artistic products aimed at promoting a stronger culture of protection for the vaquita and the biodiversity represented in the property. A community group has also been trained and equipped for the care of entangled whales and marine mammals. Known as the RABEN Alto Golfo group, they are trained in the international protocol endorsed by the International Whaling Commission for whale entanglement events, thanks to training and equipment provided by CONANP and implemented by specialists such as ECOBAC. Community participation has also been enabled and strengthened in the protection of sea turtle nesting beaches located in the northernmost parts of the Gulf of California.
Through PROCODES, several community initiatives in Golfo de Santa Clara, Sonora, have been supported to repurpose fishery waste—such as fish scales and skin—which are transformed by local artisans into bags, wallets, keychains, earrings, necklaces, and other products. Meanwhile, another community group in the same town uses fish viscera to produce biofertilizers with high commercial potential for use in regional agriculture. These two projects alone help reduce the pollution of marine and coastal areas while also contributing to the local economy and promoting a more respectful relationship with nature. Additionally, training has been promoted on the proper disposal of other waste, such as used tires, which are transformed into sculptures to prevent coastal pollution.
With regards to the vaquita and bycatch in illegal totoaba and shrimp fisheries, there are regular stakeholder meetings and strong communication with local communities, as well as non-profit support for vaquita protection (e.g., Sea Shepherd). However, these relationships are volatile and can inhibit protection and management efforts (IWC 2024). Until 2024, it appeared the vaquita was doomed to extinction due to illegal gillnet fishing in the Upper Gulf, controlled by organized crime and facilitated by corruption. However, the emplacement of ~200 cement-weighted steel hooks on the seafloor of the vaquita reserve by CONANP and the Mexican Navy has successfully stopped the gillnet fishing in this area and hopes are that the vaquita population (only ~10 individuals) will recover.
Efforts carried out by CONANP in coordination with local community groups that benefit from subsidy programs, include both PROREST (Program for the Protection and Restoration of Ecosystems and Priority Species) and PROCODES (Conservation Program for Sustainable Development). These programs enable local participation in conservation, protection, restoration, and biodiversity monitoring actions within the marine portion of this component of the World Heritage property; and on the other, in community participation in sustainable development projects that guide users toward better economic practices in the use and management of natural resources.
In the case of PROREST-supported actions, young people from San Felipe, Baja California, participate in visual identification of vaquita and marine mammals through a training and equipment process aimed at building local capacity to increase available data on visual monitoring of the vaquita. Additionally, fishers participate in acoustic monitoring activities, given their extensive experience in deploying and replacing acoustic detectors that identify vaquita echolocation clicks, which helps guide visual monitoring efforts within the vaquita refuge area. Furthermore, fishers from that locality, as well as from Golfo de Santa Clara, Sonora, have participated in ghost net removal activities, known as “grampineo,” in the vaquita's habitat and adjacent zones (State Party of Mexico, 2025). On another front, community groups contribute to the collection, deactivation, shredding, and transformation of ghost nets or nets seized by authorities. Once shredded, these nets generate plastic waste that is repurposed by the community group using 3D printing and resins to create sculptures, keychains, and various artistic products aimed at promoting a stronger culture of protection for the vaquita and the biodiversity represented in the property. A community group has also been trained and equipped for the care of entangled whales and marine mammals. Known as the RABEN Alto Golfo group, they are trained in the international protocol endorsed by the International Whaling Commission for whale entanglement events, thanks to training and equipment provided by CONANP and implemented by specialists such as ECOBAC. Community participation has also been enabled and strengthened in the protection of sea turtle nesting beaches located in the northernmost parts of the Gulf of California.
Through PROCODES, several community initiatives in Golfo de Santa Clara, Sonora, have been supported to repurpose fishery waste—such as fish scales and skin—which are transformed by local artisans into bags, wallets, keychains, earrings, necklaces, and other products. Meanwhile, another community group in the same town uses fish viscera to produce biofertilizers with high commercial potential for use in regional agriculture. These two projects alone help reduce the pollution of marine and coastal areas while also contributing to the local economy and promoting a more respectful relationship with nature. Additionally, training has been promoted on the proper disposal of other waste, such as used tires, which are transformed into sculptures to prevent coastal pollution.
With regards to the vaquita and bycatch in illegal totoaba and shrimp fisheries, there are regular stakeholder meetings and strong communication with local communities, as well as non-profit support for vaquita protection (e.g., Sea Shepherd). However, these relationships are volatile and can inhibit protection and management efforts (IWC 2024). Until 2024, it appeared the vaquita was doomed to extinction due to illegal gillnet fishing in the Upper Gulf, controlled by organized crime and facilitated by corruption. However, the emplacement of ~200 cement-weighted steel hooks on the seafloor of the vaquita reserve by CONANP and the Mexican Navy has successfully stopped the gillnet fishing in this area and hopes are that the vaquita population (only ~10 individuals) will recover.
Legal framework
The General Law of Ecological Equilibrium and Environmental Protection (La Ley general del equilibrio ecológico y la protección al ambiente (LGEEPA) provides the overarching legislative framework for the establishment and management of protected areas in Mexico. Most of the islands and all marine areas of this serial site are the property of the Federal Government (World Heritage Committee, 2010; UNESCO/IUCN, 2017). In addition to protected area laws, a number of legislative instruments provide a framework for protection of certain endangered species of flora and fauna. In order to address the threat to the vaquita from gillnet fishing in the Upper Gulf, a number of additional legal instruments have been introduced, including a ban on the use of gillnets in the Upper Gulf of California (State Party of Mexico, 2020). The legal framework is sufficient and integrated into the management system of the site, however, there have been serious issues of enforcement and implementation - with regards to illegal fishing activities within some areas of the site - which results in less effective management and some site values are diminishing, e.g., the vaquita which is severely diminished (IWC, 2024). Although totoaba is a listed (endangered) species, there has never been a full stock assessment and many fisheries biologists and ecologist do not consider this species to be threatened (although the use of gillnets to capture them is highly destructive and unsustainable).
Governance arrangements
These component parts are under the administration of the National Commission of Natural Protected Areas, although other agencies of the three levels of government (federal, state, and municipal) are involved in their management. In part due to effective governance, the property has four natural protected areas certified on the IUCN Green List of protected and conserved areas. One of the most relevant achievements is the re-certification of San Pedro Mártir Island, with validity for five years. There are Advisory Councils composed of various stakeholders that engage in conservation and management planning activities of the relevant component part.
For example, on Islas Marietas, there is an Advisory Council that meets regularly and includes representation from various stakeholders interested in the conservation and management of the Park. Council members provide advice and contribute important information for decision-making, monitor the activities carried out in the protected area, and make constructive proposals on issues of interest. Additionally, other government entities such as SEMAR (Naval Zone and Port Captaincies), SEMARNAT, and PROFEPA in their state representations are invited to participate and are kept informed of the Council’s agreements and recommendations (IUCN Consultation, 2025).
However, governance arrangements do not appear to be functional in some areas given the continued and increasing illegal fishery for totoaba (IWC 2023, 2024).
For example, on Islas Marietas, there is an Advisory Council that meets regularly and includes representation from various stakeholders interested in the conservation and management of the Park. Council members provide advice and contribute important information for decision-making, monitor the activities carried out in the protected area, and make constructive proposals on issues of interest. Additionally, other government entities such as SEMAR (Naval Zone and Port Captaincies), SEMARNAT, and PROFEPA in their state representations are invited to participate and are kept informed of the Council’s agreements and recommendations (IUCN Consultation, 2025).
However, governance arrangements do not appear to be functional in some areas given the continued and increasing illegal fishery for totoaba (IWC 2023, 2024).
Integration into local, regional and national planning systems (including sea/landscape connectivity)
The World Heritage site is well integrated in the national system of protected areas and through CONANP with regional and national planning systems (Bath and Putney, 2010). The Mexican State, as a regional conservation strategy and to strengthen the integrity and OUV of the property, in 2024 issued the Federal Decree that established the marine area adjacent to Isla Isabel National Park under a protection regime with the character of a natural protected area. This is an important measure that strengthens the management, care and conservation of this element and, consequently, of the property (State Party of Mexico, 2025).
Boundaries
The site was inscribed on the World Heritage List in 2005 and was subsequently extended in 2007 and 2011. Currently it comprises 12 components and extends over 688,588 ha. The serial approach is an adequate reflection of the biogeographic range and diversity of the Gulf of California and its islands (World Heritage Committee, 2013). The site as a whole has clearly marked boundaries that are effective in relation protection.
With regards to the vaquita, the boundary of this species critical habitat, including a buffer zone, is clearly mapped and the spatial distribution of the vaquita population is monitored regularly and this specific boundary updated as needed (IWC 2023, 2024)
With regards to the vaquita, the boundary of this species critical habitat, including a buffer zone, is clearly mapped and the spatial distribution of the vaquita population is monitored regularly and this specific boundary updated as needed (IWC 2023, 2024)
Overlapping international designations
The property overlaps with the El Vizcaino Biosphere Reserve, Islas Marias Biosphere Reserve and the Isla San Pedro Mártir Ramsar site, along with other Ramsar sites (Humedales de Bahía Adair, Canal del Infiernillo y esteros del territorio Comcaac, Estero El Soldado, Isla San Pedro Mártir, Lagunas de Santa María-Topolobampo-Ohuira, Marismas Nacionales, Isla Rasa, Parque Nacional Bahía de Loreto, Balandra, Parque Nacional Cabo Pulmo, Sistema Lagunar San Ignacio - Navachiste - Macapule, Humedales del Delta del Río Colorado and IUCN: Corredor Costero La Asamblea-San Francisquito; Humedales de la Laguna La Cruz; Complejo Lagunar Bahía Guásimas - Estero Lobos; Laguna Playa Colorada-Santa María La Reforma; Ensenada de Pabellones; Sistema Lagunar Ceuta; Parque Nacional Isla Isabel; Islas Marietas; Sistema Lagunar Agiabampo - Bacorehuis - Río Fuerte Antiguo). As the management authority is the same across the designations it can be assumed that there is some level of coordination, however specific information could not be ascertained to provide a detailed analysis.
Implementation of World Heritage Committee decisions and recommendations
Some decisions and recommendations have been implemented by the State party, including those from other relevant organisations, e.g. the documented reduction in illegal fishing activities within the core habitat of the vaquita is due to the installation of anti‐gillnet devices by CONANP and the Mexican Navy (IWC 2023). For the period 2020 to 2023, a series of actions or corrective measures have been designed to mitigate threats to the attributes and values of the property in the twelve elements that comprise it, which were approved in Decision 45 COM 7A.2 at the 45th Session of the World Heritage Committee in 2023 (State Party of Mexico, 2025). At the 45th Session of the World Heritage Committee, corrective measures were approved for the Islands and Protected Areas of the Gulf of California property, in accordance with the Mexican Government's Plan of Compliance to Prevent Illegal Fishing of and Trade in Totoaba, its Parts and/or Derivatives, for the Conservation of the Vaquita (CITES Action Plan), as part of the Mexican Government's commitments to comply with international treaties and obligations in a coordinated manner.
Despite the unprecedented interinstitutional efforts by the Mexican Government and its partners, the situation with illegal totoaba fishing in the Upper Gulf continues to remain of serious concern and the decline of the vaquita population has not been reversed yet (UNESCO, 2019), which led to a Decision by the World Heritage Committee to inscribe this site on the List of World Heritage in Danger (World Heritage Committee, 2019). The Desired State of Conservation of the property was defined for the period 2020-2024 and adopted in Decision 46 COM 7A.43 of the World Heritage Committee at its 46th session. Although there has been significant progress (e.g. a decrease in the number of illegal vessels in the ZZ and VRZ), many aspects require further efforts and time to take effect. The benthic hooks emplaced in the vaquita refuge may be working to eliminate gillnetting but another year or two needs to pass before any conclusions can be reached (Vidal et al., 2024).
Despite the unprecedented interinstitutional efforts by the Mexican Government and its partners, the situation with illegal totoaba fishing in the Upper Gulf continues to remain of serious concern and the decline of the vaquita population has not been reversed yet (UNESCO, 2019), which led to a Decision by the World Heritage Committee to inscribe this site on the List of World Heritage in Danger (World Heritage Committee, 2019). The Desired State of Conservation of the property was defined for the period 2020-2024 and adopted in Decision 46 COM 7A.43 of the World Heritage Committee at its 46th session. Although there has been significant progress (e.g. a decrease in the number of illegal vessels in the ZZ and VRZ), many aspects require further efforts and time to take effect. The benthic hooks emplaced in the vaquita refuge may be working to eliminate gillnetting but another year or two needs to pass before any conclusions can be reached (Vidal et al., 2024).
Climate action
Although there is no unified climate adaptation or mitigation strategy for the entire property, there are various actions being implemented to address climate change. An overall strategy would ensure a more coordinated approach in implementation and monitoring.
Some examples of climate action (State Party of Mexico, 2025):
- Ecotourism is one of the activities being promoted with the Comca'ac community as a productive diversification strategy and as a means of adapting to climate change to reduce their socioeconomic vulnerability. In the period 2022, 2023 and 2024, CONANP granted 60 authorizations for tourism service providers (TSP), 17 authorizations were granted to the Comca'ac ethnic group, representing 18% of the authorizations granted to operate on Tiburón Island.
- A Research and Climate Change Sub-Council was established on San Lorenzo Archipelago National Park.
- In 2023 and 2024 the Reef Systems Laboratory of the Autonomous University of Baja California Sur, in collaboration with CONANP, conducted several reef monitoring surveys in Balandra, as part of a study that sought to describe the consequences of the 2023-2024 bleaching on the structure, function and ecosystem services provided by the reefs.
- Through the Program for the Protection and Restoration of Ecosystems and Priority Species (PROREST) various projects are implemented in the component parts e.g. on Islas Marietas National Park as part of the recovery of the reefs in the area, between 2023 and 2024 more than 600 coral
fragments of the Pocillopora genus were placed and are being monitored to evaluate their adaptation and development in the environment, in order to carry out further coral reef restoration work.
Some examples of climate action (State Party of Mexico, 2025):
- Ecotourism is one of the activities being promoted with the Comca'ac community as a productive diversification strategy and as a means of adapting to climate change to reduce their socioeconomic vulnerability. In the period 2022, 2023 and 2024, CONANP granted 60 authorizations for tourism service providers (TSP), 17 authorizations were granted to the Comca'ac ethnic group, representing 18% of the authorizations granted to operate on Tiburón Island.
- A Research and Climate Change Sub-Council was established on San Lorenzo Archipelago National Park.
- In 2023 and 2024 the Reef Systems Laboratory of the Autonomous University of Baja California Sur, in collaboration with CONANP, conducted several reef monitoring surveys in Balandra, as part of a study that sought to describe the consequences of the 2023-2024 bleaching on the structure, function and ecosystem services provided by the reefs.
- Through the Program for the Protection and Restoration of Ecosystems and Priority Species (PROREST) various projects are implemented in the component parts e.g. on Islas Marietas National Park as part of the recovery of the reefs in the area, between 2023 and 2024 more than 600 coral
fragments of the Pocillopora genus were placed and are being monitored to evaluate their adaptation and development in the environment, in order to carry out further coral reef restoration work.
Management plan and overall management system
The National Commission of Protected Natural Areas (CONANP), the Federal Prosecutor's Office for Environmental Protection (PROFEPA) and other relevant agencies have formed a series of community networks, comprising environmental guardians, monitors, and promoters with the aim of implementing various actions for the conservation of the environmental attributes, values and services of the site. This action was initiated in 2024 and it's impact is yet to be assessed, although the creation of community brigades that participate in conservation actions dates back to well before 2024. There is also strong collaboration with PROFEPA for the certification of these brigades as Community Watchkeepers.
Management of the World Heritage site is exercised by the National Commission for Protected Areas (CONANP), a specialized agency of the Mexican Ministry of the Environment and Natural Resources (SEMARNAT). CONANP is a decentralized agency, and direct management activities for the property are implemented through three Regional Directorates (World Heritage Committee, 2010; CONAP, 2006; UNESCO/IUCN, 2017). Most of the marine protected areas of the Gulf have developed and published Management Programs through participatory processes, which are regularly updated in accordance to issues like tourism. While all component protected areas that are part of the property have well established management programmes and plans in place, no integrated management structure exists for the entire serial site, although coordination between different protected areas and management units appears to be well organized (UNESCO/IUCN, 2017).
Management of the World Heritage site is exercised by the National Commission for Protected Areas (CONANP), a specialized agency of the Mexican Ministry of the Environment and Natural Resources (SEMARNAT). CONANP is a decentralized agency, and direct management activities for the property are implemented through three Regional Directorates (World Heritage Committee, 2010; CONAP, 2006; UNESCO/IUCN, 2017). Most of the marine protected areas of the Gulf have developed and published Management Programs through participatory processes, which are regularly updated in accordance to issues like tourism. While all component protected areas that are part of the property have well established management programmes and plans in place, no integrated management structure exists for the entire serial site, although coordination between different protected areas and management units appears to be well organized (UNESCO/IUCN, 2017).
Law enforcement
An illegal fishery for an endangered fish species, that also causes a bycatch of a critically endangered cetacean species, continues unabated and has increased in recent years (IWC, 2024). Much of what law enforcement exists is centred on the part of the site that these species' inhabit, perhaps decreasing patrol and monitoring activities elsewhere in the site.
With the systematic application of procedures and sanctions to those who enter the Zero Tolerance Zone (ZZ) for any unauthorized activity, 19 administrative proceedings have been resolved with fines totalling MXN 5,387,632.70; as well as nine resolutions of administrative proceedings with fines totalling MXN 3,601,960.28 for unauthorized activities in the Vaquita Refuge Zone (VRZ). In the same sense, the attention and follow-up to criminal proceedings, from January 1st, 2018 to September 30th, 2024, has resulted in the prosecution of 30 investigation files, the sentence of 17 people to prison, and a total amount of more than $114.5 million MXN of monetary charges corresponding to the to the reparation of damages sentenced in abbreviated proceedings, conditional suspension of proceedings, and convictions issued in first instance oral trials. The confiscation of assets related to illegal activities, from April 2023 to September 2024, included 44 gillnets with a total length of 11,200 meters. In addition to the destruction of 131 ghost gillnets with a total length of 38,092 meters found in the ZZ, taking into account those found in previous years and destroyed during this period. A project for the elimination of illegal fishing gear was designed and implemented, with the installation of more than 400 concrete blocks through the "Blocking Project", which has discouraged and prevented the setting of gillnets, as well as facilitating the immediate removal of identified gillnets. These and other measures described in this report have led to a decrease in the presence of vessels in the ZZ and VRZ: compared to 2022, 49% fewer vessels were detected by the maritime radar system in the ZZ and 95% fewer in the VRZ during the entire year of 2023. In 2024, the trend continued, with only four vessels detected in the ZZ from January to September (State Party of Mexico, 2025).
International cooperation efforts are aimed at combating the illegal trade in totoaba. Mexico promoted the activities that allowed the creation of the Trilateral Contact Group (TCG) on Law Enforcement to Combat Illegal Trafficking in Totoaba on March 7, 2024, whose objective was to facilitate the exchange of information and cooperation for law enforcement purposes (State Party of Mexico, 2025).
With the systematic application of procedures and sanctions to those who enter the Zero Tolerance Zone (ZZ) for any unauthorized activity, 19 administrative proceedings have been resolved with fines totalling MXN 5,387,632.70; as well as nine resolutions of administrative proceedings with fines totalling MXN 3,601,960.28 for unauthorized activities in the Vaquita Refuge Zone (VRZ). In the same sense, the attention and follow-up to criminal proceedings, from January 1st, 2018 to September 30th, 2024, has resulted in the prosecution of 30 investigation files, the sentence of 17 people to prison, and a total amount of more than $114.5 million MXN of monetary charges corresponding to the to the reparation of damages sentenced in abbreviated proceedings, conditional suspension of proceedings, and convictions issued in first instance oral trials. The confiscation of assets related to illegal activities, from April 2023 to September 2024, included 44 gillnets with a total length of 11,200 meters. In addition to the destruction of 131 ghost gillnets with a total length of 38,092 meters found in the ZZ, taking into account those found in previous years and destroyed during this period. A project for the elimination of illegal fishing gear was designed and implemented, with the installation of more than 400 concrete blocks through the "Blocking Project", which has discouraged and prevented the setting of gillnets, as well as facilitating the immediate removal of identified gillnets. These and other measures described in this report have led to a decrease in the presence of vessels in the ZZ and VRZ: compared to 2022, 49% fewer vessels were detected by the maritime radar system in the ZZ and 95% fewer in the VRZ during the entire year of 2023. In 2024, the trend continued, with only four vessels detected in the ZZ from January to September (State Party of Mexico, 2025).
International cooperation efforts are aimed at combating the illegal trade in totoaba. Mexico promoted the activities that allowed the creation of the Trilateral Contact Group (TCG) on Law Enforcement to Combat Illegal Trafficking in Totoaba on March 7, 2024, whose objective was to facilitate the exchange of information and cooperation for law enforcement purposes (State Party of Mexico, 2025).
Sustainable finance
CONANP is one of the many sectors that has been badly hit by funding cuts in recent years. According to an analysis of Mexico’s draft budget for 2025 by Noroeste Civil Society for Environmental Sustainability (NOSSA), the government agency will see its budget reduced by 42% compared to 2024. It is the lowest budget since 2006, with 1,001 million pesos (about $50 million) for the management of the country’s 232 protected areas. The E016-16 program, dedicated to the conservation and management of protected natural areas, will see its budget reduced by 41.5% compared to 2024, with 118 million pesos (about $5.7 million) compared to 202 million (about $9.7 million) last year (Gabay, 2025). The extent to which this impacts directly on the property's management remains to be seen.
Through the Program of Subsidies for the Protection and Restoration of Ecosystems and Priority Species (abbreviated in Spanish as PROREST), and the Program of Subsidies Conservation for Sustainable Development (abbreviated in Spanish as PROCODES), in 2024 an investment of $36,652,151 MXN was made to support projects developed together with the communities, aimed at: aquatic and terrestrial ecosystem sanitation; ecological restoration; solid waste management; agro-ecological gardens; conservation of species; protection of nesting beaches of sea turtles; community surveillance and monitoring; training and outreach; control of exotic species; ecotourism projects and sustainable economic activities; sustainable fishing gear and aquaculture; apiaries; forestry plantations; wood-saving stoves; buoy signalling; among others (State Party of Mexico, 2025).
In Islas Marietas National Park, organized tourism service providers created a fund through visitor donations, which has been allocated to support the Park’s operations since 2016. This fund covers 90% of the requirements related to surveillance, restoration, monitoring, environmental education, and outreach (IUCN Consultation, 2025).
Through the Program of Subsidies for the Protection and Restoration of Ecosystems and Priority Species (abbreviated in Spanish as PROREST), and the Program of Subsidies Conservation for Sustainable Development (abbreviated in Spanish as PROCODES), in 2024 an investment of $36,652,151 MXN was made to support projects developed together with the communities, aimed at: aquatic and terrestrial ecosystem sanitation; ecological restoration; solid waste management; agro-ecological gardens; conservation of species; protection of nesting beaches of sea turtles; community surveillance and monitoring; training and outreach; control of exotic species; ecotourism projects and sustainable economic activities; sustainable fishing gear and aquaculture; apiaries; forestry plantations; wood-saving stoves; buoy signalling; among others (State Party of Mexico, 2025).
In Islas Marietas National Park, organized tourism service providers created a fund through visitor donations, which has been allocated to support the Park’s operations since 2016. This fund covers 90% of the requirements related to surveillance, restoration, monitoring, environmental education, and outreach (IUCN Consultation, 2025).
Staff capacity, training and development
Most of the component protected areas have a stable amount of technical staff, although in some areas the number of staff appears low compared to the size of the components. All component protected areas also have Advisory Committees which support their management (State Party of Mexico, 2016). According to the state party, there are ongoing training programmes e.g. for personnel from the Federal Environmental Protection Agency (PROFEPA), the National Commission for Aquaculture and Fisheries (CONAPESCA), the Navy Secretariat (SEMAR), the National Guard (GN) and the Mexican National Customs Agency (ANAM) operating in the region (State Party of Mexico, 2025). With regard to the promotion of alternative fishing gear, some training and workshops on the use of alternative fishing gear were held for representatives of organizations with CONAPESCA permits in the region.
Education and interpretation programmes
A number of excellent educational and community engagement programmes have been developed in many components of the World Heritage site and some of them can serve as best-practice examples worldwide (UNESCO/IUCN, 2017; State Party of Mexico, 2017, 2020, 2025). Many of these programmes were developed and are managed by non-profit organizations.
Efforts carried out by CONANP in coordination with local community groups that benefit from subsidy programs, include both PROREST (Program for the Protection and Restoration of Ecosystems and Priority Species) and PROCODES (Conservation Program for Sustainable Development). These programs enable local participation in conservation, protection, restoration, and biodiversity monitoring actions within the marine portion of this component of the World Heritage property; and on the other, in community participation in sustainable development projects that guide users toward better economic practices in the use and management of natural resources.
Efforts carried out by CONANP in coordination with local community groups that benefit from subsidy programs, include both PROREST (Program for the Protection and Restoration of Ecosystems and Priority Species) and PROCODES (Conservation Program for Sustainable Development). These programs enable local participation in conservation, protection, restoration, and biodiversity monitoring actions within the marine portion of this component of the World Heritage property; and on the other, in community participation in sustainable development projects that guide users toward better economic practices in the use and management of natural resources.
Tourism and visitation management
In some component parts, tourism has been rapidly and significantly increasing. E.g. the number of tourists visiting Cabo Pulmo National Park has increased from a total of 4,601 tourists in 2009 to 32,486 tourists in 2023, which is equivalent to a 706% increase. As of September 2024, there were 20,448 visitors.
In response and in collaboration with various stakeholders, carrying capacity studies are being carried out and inform management plan updates, e.g. in Baja California Sur a new zoning was established in the core zone of Los Islotes in conjunction with the snorkelling and diving tourist service providers, with regulations to respect the carrying capacity of the site, which is 180 people at the same time in the sea, in periods of 1.5 hours, in groups of a maximum of 10 people. In the Gulf of California Islands (Sinaloa) supervision and monitoring patrols have been carried out in coordination with other authorities (SEMAR, PROFEPA, Port Captaincy) with the aim of verifying that tourism activities are conducted in accordance with regulations.
Various stakeholders are involved in supervising visitation in both marine and terrestrial areas e.g. SEMAR, Resguardo Marítimo Federal (REMAFE), and Capitanía de Puerto supervise visits in the marine area of Flora and Fauna Protection Area Cabo San Lucas and tourism service providers, personnel from the sea turtle protection program, and volunteers from the area support with terrestrial supervision (State Party of Mexico, 2025).
In response and in collaboration with various stakeholders, carrying capacity studies are being carried out and inform management plan updates, e.g. in Baja California Sur a new zoning was established in the core zone of Los Islotes in conjunction with the snorkelling and diving tourist service providers, with regulations to respect the carrying capacity of the site, which is 180 people at the same time in the sea, in periods of 1.5 hours, in groups of a maximum of 10 people. In the Gulf of California Islands (Sinaloa) supervision and monitoring patrols have been carried out in coordination with other authorities (SEMAR, PROFEPA, Port Captaincy) with the aim of verifying that tourism activities are conducted in accordance with regulations.
Various stakeholders are involved in supervising visitation in both marine and terrestrial areas e.g. SEMAR, Resguardo Marítimo Federal (REMAFE), and Capitanía de Puerto supervise visits in the marine area of Flora and Fauna Protection Area Cabo San Lucas and tourism service providers, personnel from the sea turtle protection program, and volunteers from the area support with terrestrial supervision (State Party of Mexico, 2025).
Sustainable use
CONANP works closely with local communities to assure that their use of natural resources is sustainable (UNEP-WCMC, 2011; Bath and Putney, 2010; CONANP, 2006). However, illegal and unsustainable fishing remain of high concern in many areas, despite the efforts to develop alternative "vaquita-safe" gear for the legal curvina and shrimp fisheries to allow local fishermen to continue their work (UNESCO, 2017, 2019; UNESCO/IUCN, 2018). Furthermore, it has been previously noted that transition to sustainable and regulated fishing practices will be required across the entire serial World Heritage site to ensure its conservation in the long term (UNESCO/IUCN, 2017, 2018). It is estimated that 40% of the commercial fishing in the Gulf of California is done illegally (e.g., without permits, without reporting, in illegal fishing areas). In addition, most commercial fishing in the Gulf of California is now fully controlled by organized crime. It is likely that every fishery is over-fished in terms of maintaining sustainable stock. Also, eDNA studies have shown that 40% of the fish sold in restaurants is incorrectly labelled (and often illegally caught).
Some programmes have been ongoing, particularly with regards to providing information on alternative fishing gear, largely driven by civil society. Such a society, PESCA ABC, are dedicated to developing, testing and implementing alternative fishing gear to eliminate bycatch risk to vaquita. In 2022, an alternative gear initiative was launched, with the objective of selling harvested fish at a higher monetary rate which resulted in the fish caught under this project making double the typical value at market. The success of these efforts, including participation and community engagement is attributed to PESCA ABC, Cetacean Action Treasury, Museo de la Ballena in La Paz, Mexico, and the Monitoreo Administrativo Regional de Especies Marinas (MAREM) (IWC, 2023). The Conservation Program for Sustainable Development (PROCODES) and the Program for the Protection and Restoration of Ecosystems and Priority Species (PROREST) play a fundamental role in promoting community participation in the conservation and sustainable use of natural resources in protected natural areas (State Party of Mexico, 2025). In terms of improved fishing practices, several initiatives have been supported involving the use of alternative gear to gillnets. These include hook-and-line fishing using the Japanese Ikejime technique, the cultivation of Chione clams in floating cages, and the development of traps for snails and crabs, among other training topics and initiatives to strengthen community dialogue on alternative fishing methods.
The proportion of local fishermen and their families supporting the Biosphere Reserve Isla San Pedro Martir, particularly the core zone where fishing is not allowed, increased. The core zone is a tool that facilitates the restoration of rocky reef fish stocks. In 2012, 69% agreed on the existence of the core zone and in 2023 90.2% agreed (data taken from surveys applied in 2023 and analysed in 2024). This is strengthened by results such as the increase in biomass and sizes of some commercial fish species (State Party of Mexico, 2025).
In regards to tourism, UNESCO is in contact with SEMAR to establish guidelines on sustainable tourism in the reserve (IUCN Consultation, 2024).
Some programmes have been ongoing, particularly with regards to providing information on alternative fishing gear, largely driven by civil society. Such a society, PESCA ABC, are dedicated to developing, testing and implementing alternative fishing gear to eliminate bycatch risk to vaquita. In 2022, an alternative gear initiative was launched, with the objective of selling harvested fish at a higher monetary rate which resulted in the fish caught under this project making double the typical value at market. The success of these efforts, including participation and community engagement is attributed to PESCA ABC, Cetacean Action Treasury, Museo de la Ballena in La Paz, Mexico, and the Monitoreo Administrativo Regional de Especies Marinas (MAREM) (IWC, 2023). The Conservation Program for Sustainable Development (PROCODES) and the Program for the Protection and Restoration of Ecosystems and Priority Species (PROREST) play a fundamental role in promoting community participation in the conservation and sustainable use of natural resources in protected natural areas (State Party of Mexico, 2025). In terms of improved fishing practices, several initiatives have been supported involving the use of alternative gear to gillnets. These include hook-and-line fishing using the Japanese Ikejime technique, the cultivation of Chione clams in floating cages, and the development of traps for snails and crabs, among other training topics and initiatives to strengthen community dialogue on alternative fishing methods.
The proportion of local fishermen and their families supporting the Biosphere Reserve Isla San Pedro Martir, particularly the core zone where fishing is not allowed, increased. The core zone is a tool that facilitates the restoration of rocky reef fish stocks. In 2012, 69% agreed on the existence of the core zone and in 2023 90.2% agreed (data taken from surveys applied in 2023 and analysed in 2024). This is strengthened by results such as the increase in biomass and sizes of some commercial fish species (State Party of Mexico, 2025).
In regards to tourism, UNESCO is in contact with SEMAR to establish guidelines on sustainable tourism in the reserve (IUCN Consultation, 2024).
Monitoring
The values for which the site was inscribed are systematically monitored, in particular, monitoring of the distribution and abundance of the vaquita. This monitoring follows best practise in the field of marine mammal research and is conducted in cooperation with several research centres, international agencies, i.e., the International Whaling Commission and an international panel of academic experts. Monitoring processes are adapted yearly based on the results of the previous years monitoring (e.g., IWC, 2023, 2024).
Regarding monitoring efforts for key species—such as the Gulf silverside (Colpichthys), shorebirds, and the vaquita—significant progress has been made, indicating good ecological conditions within the property.
Regarding monitoring efforts for key species—such as the Gulf silverside (Colpichthys), shorebirds, and the vaquita—significant progress has been made, indicating good ecological conditions within the property.
Research
Almost all major oceanographic processes occurring in the planet’s oceans are present in the Gulf of California, which gives it extraordinary importance for the study of marine and coastal processes. The islands are seen as natural laboratories for the examining of speciation, colonization, interaction and adaptation among species, as well as for geological and evolutionary research. MacArthur and Wilson’s theory of island biogeography was tested there. The National University of Mexico has monitored seabird populations on Isla Isabel since 1981. The Universities of Nayarit and Guadalajara also use the island’s excellent opportunities for research. Much remains unknown but numerous research projects are ongoing. Research is also supported by a number of NGOs working in the Gulf of California, mainly WWF, CI, TNC, COBI, PRONATURA Noroeste, and PRONAT. For the vaquita, there is a targeted research programme that provides comprehensive and regular advice to the management plan. For this species, there is comprehensive knowledge and active engagement of multiple stakeholders, so the research itself is highly effective.
In the Sonora region, research activities related to seabirds, mammals, endemic reptiles and vegetation have been carried out by researchers from the Metropolitan Autonomous University - Xochimilco Unit, the University of Guadalajara, the Autonomous University of Mexico, the Scientific Research and Higher Education Center of Ensenada (CICESE), the Interdisciplinary Center for Marine Sciences - IPN, the Northwest Biological Research Center, the Food and Development Research Center (CIAD) - Guaymas Unit, and Prescott College (in Kino Bay). They also collaborate with CSOs such as Community and Biodiversity, and PRONATURA Noroeste (IUCN Consultation, 2024).
In the Sonora region, research activities related to seabirds, mammals, endemic reptiles and vegetation have been carried out by researchers from the Metropolitan Autonomous University - Xochimilco Unit, the University of Guadalajara, the Autonomous University of Mexico, the Scientific Research and Higher Education Center of Ensenada (CICESE), the Interdisciplinary Center for Marine Sciences - IPN, the Northwest Biological Research Center, the Food and Development Research Center (CIAD) - Guaymas Unit, and Prescott College (in Kino Bay). They also collaborate with CSOs such as Community and Biodiversity, and PRONATURA Noroeste (IUCN Consultation, 2024).
Effectiveness of management system and governance in addressing threats outside the site
The Management Program for the site takes notice of the impacts to the Gulf of California coast from “upstream” urban and industrial areas. Given the number and immensity of impacts, most attention is focused on wetlands since they are the breeding and nursery habitats of much of the Gulf’s fish. The resources available for this large task are extremely limited in comparison to the immensity of the problem (CONANP, 2006). Illegal fishing activities, particular illegal fishing of totoaba in the Upper Gulf of California, both within and outside the component protected areas of the site, remain of concern and even unprecedented inter-agency efforts by CONANP, the Mexican Navy and PROFEPA have not succeeded so far in eliminating the problem (UNESCO/IUCN, 2017; State Party of Mexico, 2025). Nevertheless, efforts with local communities and cooperation with destination and transit countries involved in the illegal trade of totoaba have been addressing key threats from outside the site.
Effectiveness of management system and governance in addressing threats inside the site
Formal recommendations aimed at safeguarding the vaquita have not been effectively implemented, and results from the comprehensive research programme show clearly that that the vaquita population may not survive in the long term (IWC, 2024). The only effective conservation strategy to date has been the implementation of benthic hooks that successfully deter gillnet fishing. If the area of these hooks can be increased, there is a good probability of saving the vaquita.
In 2023, the US Government expressed serious concerns with regards to violation of CITES and directed that;
(1) a high-level dialogue be undertaken with the Government of Mexico to discuss the steps it will take to reduce illegal trafficking of totoaba and to review its CITES Compliance Action Plan
(2) relevant agencies assist and support Mexico’s compliance, anti‑trafficking, anti-corruption, and other measures
(3) the Secretaries of the Interior, Commerce, State and the US Trade Representative ‘assess Mexico’s enforcement actions and implementation of its CITES Compliance Action Plan in 2024.
Further, the CITES Secretariat conducted missions to Mexico and the United States to assess efforts by both countries to prevent the illegal trade of totoaba. This report will be reviewed by the CITES Standing Committee in February 2025 (IWC, 2023).
Beyond this, the property has four natural protected areas certified on the IUCN Green List of protected and conserved areas. One of the most relevant achievements is the re-certification of San Pedro Mártir Island, with validity for five years. This was achieved thanks to effective governance and planning, in addition to the successful results in its conservation and management and the work of the staff of the protected area, in coordination with the communities, civil society organizations, academia, service providers, and all those sectors that have a relationship with this element of the property. The CONANP evaluation of the index of effectiveness (i-effectiveness) for 2023, the management of 10 of the 12 components of the Serial Property proved to be highly effective (State Party of Mexico, 2025).
In 2023, the US Government expressed serious concerns with regards to violation of CITES and directed that;
(1) a high-level dialogue be undertaken with the Government of Mexico to discuss the steps it will take to reduce illegal trafficking of totoaba and to review its CITES Compliance Action Plan
(2) relevant agencies assist and support Mexico’s compliance, anti‑trafficking, anti-corruption, and other measures
(3) the Secretaries of the Interior, Commerce, State and the US Trade Representative ‘assess Mexico’s enforcement actions and implementation of its CITES Compliance Action Plan in 2024.
Further, the CITES Secretariat conducted missions to Mexico and the United States to assess efforts by both countries to prevent the illegal trade of totoaba. This report will be reviewed by the CITES Standing Committee in February 2025 (IWC, 2023).
Beyond this, the property has four natural protected areas certified on the IUCN Green List of protected and conserved areas. One of the most relevant achievements is the re-certification of San Pedro Mártir Island, with validity for five years. This was achieved thanks to effective governance and planning, in addition to the successful results in its conservation and management and the work of the staff of the protected area, in coordination with the communities, civil society organizations, academia, service providers, and all those sectors that have a relationship with this element of the property. The CONANP evaluation of the index of effectiveness (i-effectiveness) for 2023, the management of 10 of the 12 components of the Serial Property proved to be highly effective (State Party of Mexico, 2025).
The site has a sound management system, with highly dedicated CONANP staff responsible for the management of individual component protected areas which comprise this serial World Heritage site. While no integrated management structure of the plan exists for the entire site, coordination between different protected areas and management units appears to be well organized in practice. Years of working with the communities has led to generally good relations and a number of highly successful programmes have been developed, including monitoring programmes with participation of local communities. Nevertheless, despite efforts to strengthen law enforcement and surveillance activities, the situation with illegal fishing in the Upper Gulf is of serious concern. While concentrated in one area of this large serial site, it shows overall vulnerability of the system to illegal and unregulated fishing activities and is currently under the control of organized crime.
Good practice examples
1. A number of highly successful community engagement programmes have been developed in some components and can serve as best-practice examples. These are multi-sectorial projects involving different levels of governance, NGO’s, academies and community to develop capacities to coordinate actions that benefit the people and the ecosystems. An example of this is the active involvement of the Comca’ac’s people in conservation and research efforts.
2. Successful eradication of introduced species, such as rats, on several islands (i.e. Farallón de San Ignacio and San Pedro Mártir islands) also serves as a good practice example. There is strong community participation in conservation actions, including monitoring, surveillance, sanitation, and control of invasive exotic species. In the latter, communities were involved in the eradication of goats and the control of salt cedar and carrizo on Venados Island.
2. Successful eradication of introduced species, such as rats, on several islands (i.e. Farallón de San Ignacio and San Pedro Mártir islands) also serves as a good practice example. There is strong community participation in conservation actions, including monitoring, surveillance, sanitation, and control of invasive exotic species. In the latter, communities were involved in the eradication of goats and the control of salt cedar and carrizo on Venados Island.
Striking natural beauty
Low Concern
Trend
Stable
The aesthetic values of the site have been well preserved. Many of the islands remain in pristine conditions and are not affected by any development (UNESCO/IUCN, 2017). The biggest issues, both correctable (in theory) are unsustainable fishing and localized anthropogenic-influenced runoff to the sea (creating low-oxygen regions). It remains to be seen to what extent ocean warming impacts the Gulf. Key reasons why the Gulf remains quite healthy are: influence of Mexican civil society organizations and academics, extreme tidal flushing from the open Pacific, long stretches of minimally inhabited coastline on both the east and west shores of the Gulf (IUCN Consultation, 2025).
A natural laboratory for the study of speciation and oceanographic processes
High Concern
Trend
Deteriorating
While many of ecological and oceanographic processes continue unimpaired, concerns have increased with regards to the future of some key species, particularly the critically endangered vaquita (IWC, 2024). Law enforcement appears to be less effective in some areas (IWC, 2024), while there are indications that over the past year improvements have been made in others (State Party of Mexico, 2025). Overfishing and other illegal and/or unsustainable fishing practises may also severely impact the entire ecosystem.
Furthermore, the impacts from climate change are being felt through temperature and sea level anomalies, due to Niño/Niña events as well as other oceanographic and climatic processes. During 2023 and 2024 the Reef Systems Laboratory of the Autonomous University of Baja California Sur, in collaboration with CONANP, conducted several reef monitoring surveys in Balandra, as part of a study that sought to describe the consequences of the 2023-2024 bleaching on the structure, function and ecosystem services provided by the reefs. It was found that the warming of the sea due to the El Niño event of 2023 had a great impact on the coral fauna and associated invertebrates, causing decreases in most of the functional indicators and environmental services. On the other hand, the ichthyofauna also presented modifications in abundance and specific composition, which lowered its value as an ecosystem provider of social services, although functional diversity remained stable. The data show that the area's communities have limited resilience capacity (State Party of Mexico, 2025). However, despite these concerns there remain a great many coastal and oceanic regions within the Gulf of California that serve as refuges for species threatened elsewhere, and these may serve as recruitment sources over time and fluctuations in ecological conditions elsewhere. Long-term monitoring studies conducted by Dr. Héctor Reyes (UABC) in Cabo Pulmo and Espíritu Santo show that, although oceanographic phenomena such as El Niño, the Pacific Decadal Oscillation, and the 2023 ocean warming event (linked to a volcanic eruption) caused temperature variations and population changes—including a coral bleaching episode in Cabo Pulmo—subsequent surveys documented the recovery of the reefs just a few months after the event (unpublished reports by Dr. Reyes).
Furthermore, the impacts from climate change are being felt through temperature and sea level anomalies, due to Niño/Niña events as well as other oceanographic and climatic processes. During 2023 and 2024 the Reef Systems Laboratory of the Autonomous University of Baja California Sur, in collaboration with CONANP, conducted several reef monitoring surveys in Balandra, as part of a study that sought to describe the consequences of the 2023-2024 bleaching on the structure, function and ecosystem services provided by the reefs. It was found that the warming of the sea due to the El Niño event of 2023 had a great impact on the coral fauna and associated invertebrates, causing decreases in most of the functional indicators and environmental services. On the other hand, the ichthyofauna also presented modifications in abundance and specific composition, which lowered its value as an ecosystem provider of social services, although functional diversity remained stable. The data show that the area's communities have limited resilience capacity (State Party of Mexico, 2025). However, despite these concerns there remain a great many coastal and oceanic regions within the Gulf of California that serve as refuges for species threatened elsewhere, and these may serve as recruitment sources over time and fluctuations in ecological conditions elsewhere. Long-term monitoring studies conducted by Dr. Héctor Reyes (UABC) in Cabo Pulmo and Espíritu Santo show that, although oceanographic phenomena such as El Niño, the Pacific Decadal Oscillation, and the 2023 ocean warming event (linked to a volcanic eruption) caused temperature variations and population changes—including a coral bleaching episode in Cabo Pulmo—subsequent surveys documented the recovery of the reefs just a few months after the event (unpublished reports by Dr. Reyes).
Diversity of terrestrial and marine life
Critical
Trend
Deteriorating
The situation varies across this large serial site.
An ecological assessment of all marine protected areas (MPAs) in Northeast Mexico has been undertaken by CONANP (2016) through ecological scorecards compiled for individual protected areas based on a number of indicators. The results show that marine areas are in good condition in parts of the site (Cabo Pulmo, San Lorenzo), but are in poor condition and showing decline in other parts, particularly in south-eastern parts along the coast of Nayarit state (Isla Isabel and Islas Marietas) (UNESCO/IUCN, 2017).
Regarding monitoring efforts for key species—such as the Gulf silverside (Colpichthys), shorebirds, and the vaquita—significant progress has been made, indicating good ecological conditions within the property.
The critically endangered vaquita, endemic to the Gulf of California, is at risk of imminent extinction. The situation with illegal fishing and the continued decline of the vaquita population has led to the inscription of the site on the List of World Heritage in Danger (World Heritage Committee, 2019). Its numbers declined from approximately 300 at the time of the inscription of the property to 59 in 2015, and further to an estimation of 30 individuals in 2016 (UNESCO, 2017). As of summer 2018, it was estimated that fewer than 19 individuals remained. Despite all the measures implemented to combat illegal fishing, between Match 2016 and March 2019, a total of 10 vaquitas killed in gillnets were found (Jaramillo-Legoretta et al., 2019). The results from acoustic monitoring show that from 2021 to 2023 the negative trend of the population has decreased compared to previous years, and that in terms of the annual rate of acoustic detections, from 2011 to 2018 it has had an average annual decrease of 45%, while from 2021 to 2023, the average percentage decrease was 14.4%, considering ZZ (State Party of Mexico, 2025). In the case of vaquita monitoring cruises, in 2023 between 10 and 13 individual vaquitas were recorded, including two calves. This suggests that the species is still reproducing. During the 2024 cruise, juveniles were identified that may correspond to the calves seen the previous year, indicating that they continue to grow and develop in a habitat that still offers favorable ecological conditions for population recovery (IUCN Consultation, 2025). It should be noted that current annual vaquita monitoring via observation cruises covers an area of 22,500 ha, corresponding to the so-called “zero tolerance zone,” which is protected by weighted blocks that keep it free from gillnets. However, the full vaquita refuge area spans 184,100 ha, which remains the species' habitat. With increased financial support for monitoring, greater data collection capacity on the vaquita’s population status could be achieved.
The California sea lion (Zalophus californianus) is a species considered a bio-indicator of the health of the pelagic marine ecosystem, and whose distribution is found throughout the Gulf of California. Regarding the sea lion populations on islands with breeding colonies such as San Pedro Nolasco, San Esteban and San Jorge of the APFF IGC (off the coast of Sonora) and the Isla San Pedro Mártir as a Biosphere Reserve in Sonora, its trend is stable and the population fluctuations it presents are related to changes in sea surface temperature caused by climatic and oceanographic phenomena such as El Niño (ENSO) or the Pacific decadal oscillation (CONANP 2023). There is also an important sea lion rookery on Farallón de San Ignacio Island, with a colony of California sea lions (Zalophus californianus) and also records of the Guadalupe fur seal (Arctophoca philippii townsendi). Both species are listed under SEMARNAT’s NOM-059-2010. Park rangers from the Protected Area conduct biological monitoring at this site.
The property hosts a significant number of different seabird, waterfowl and landbird species and is offers important refuge and breeding sites. Currently, the only stable nesting colony of frigate birds (Fregata magnificens) that exists in the entire Baja California peninsula is the one located in San Gabriel Bay on Espiritu Santo Island. A total of 183 yellow-legged gull nests were recorded on Gaviota, Merito, Ballena, Gallo and Gallina islets with an average of 1.90 eggs per nest and 0.45 chicks per nest. Compared to previous years, nesting was low for both yellow-legged gulls and brown pelicans, with fewer nests, fewer eggs per nest, and therefore fewer chicks during this season. In 2023, the El Niño meteorological phenomenon was one of the five most intense episodes in history, causing sea temperatures in the central and eastern equatorial Pacific to warm significantly (1.5 °C above average). This had effects on plankton productivity (decreases) resulting in unfavourable conditions for zooplankton, larvae, invertebrates and pelagic fish that feed on plankton. In the case of sardines, they move towards colder and deeper waters, thus decreasing the availability of food for seabirds. In 2024, CONANP in collaboration with the University of Guadalajara, conducted the annual nest count on San Pedro Martir Island. Although there were notable variations, the numbers of blue-footed boobies (4,673 individuals in 2021 to 430 in 2024), brown-footed boobies (1331 individuals in 2021 to 260 in 2024) and brown pelicans (996 individuals in 2021 to 602 in 2024) in recent years are only a small fraction of the historical estimate of colony size. It is difficult to determine the causes of colony size reduction in all three species, it may be directly and indirectly related to climate variability events (State Party of Mexico, 2025).
Endemic reptiles and rodents: Annual population data (density) on Sonomar were recorded during 2024 for six species of importance: spiny iguana (Ctenosaura nolascensis), lizard (Uta nolascensis), gecko (Aspidoscelis bacatus) and field mouse (Peromyscus boylii) from San Pedro Nolasco Island and for the iguana (Sauromalus varius), mouse (Peromyscus callatus), mouse (Chaetodipus intermedio) and the rat cambalachera (Neotoma varia). Fluctuations in island population densities could be directly and indirectly related to climate variability events (e.g., El Niño/climate change events), however, the densities recorded are within the threshold of natural variations recorded over more than 10 years of monitoring (State Party of Mexico, 2025). This trend is also observed in other component parts. For example, on San Pedro Martir Island systematic monitoring of huico (Aspidoscelies martyris) and the spotted side lizard (Uta palmeri) indicates that their populations have suffered changes related to temperature and sea level anomalies, due to Niño/Niña events as well as other oceanographic and climatic processes (State Party of Mexico, 2025).
Despite these concerns, to date no species of marine vertebrates or invertebrates have gone extinct, and only the vaquita is today critically threatened. The vast regions of marine coastline that are largely uninhabited on the islands and the Baja California Peninsula provide a "buffer" as a refuge for many of the regions species. Many species that have reached "commercial extinction" have rebounded after cessation of commercial fishing, indicative of resilience in the Gulf's ecosystems (IUCN Consultation, 2025).
An ecological assessment of all marine protected areas (MPAs) in Northeast Mexico has been undertaken by CONANP (2016) through ecological scorecards compiled for individual protected areas based on a number of indicators. The results show that marine areas are in good condition in parts of the site (Cabo Pulmo, San Lorenzo), but are in poor condition and showing decline in other parts, particularly in south-eastern parts along the coast of Nayarit state (Isla Isabel and Islas Marietas) (UNESCO/IUCN, 2017).
Regarding monitoring efforts for key species—such as the Gulf silverside (Colpichthys), shorebirds, and the vaquita—significant progress has been made, indicating good ecological conditions within the property.
The critically endangered vaquita, endemic to the Gulf of California, is at risk of imminent extinction. The situation with illegal fishing and the continued decline of the vaquita population has led to the inscription of the site on the List of World Heritage in Danger (World Heritage Committee, 2019). Its numbers declined from approximately 300 at the time of the inscription of the property to 59 in 2015, and further to an estimation of 30 individuals in 2016 (UNESCO, 2017). As of summer 2018, it was estimated that fewer than 19 individuals remained. Despite all the measures implemented to combat illegal fishing, between Match 2016 and March 2019, a total of 10 vaquitas killed in gillnets were found (Jaramillo-Legoretta et al., 2019). The results from acoustic monitoring show that from 2021 to 2023 the negative trend of the population has decreased compared to previous years, and that in terms of the annual rate of acoustic detections, from 2011 to 2018 it has had an average annual decrease of 45%, while from 2021 to 2023, the average percentage decrease was 14.4%, considering ZZ (State Party of Mexico, 2025). In the case of vaquita monitoring cruises, in 2023 between 10 and 13 individual vaquitas were recorded, including two calves. This suggests that the species is still reproducing. During the 2024 cruise, juveniles were identified that may correspond to the calves seen the previous year, indicating that they continue to grow and develop in a habitat that still offers favorable ecological conditions for population recovery (IUCN Consultation, 2025). It should be noted that current annual vaquita monitoring via observation cruises covers an area of 22,500 ha, corresponding to the so-called “zero tolerance zone,” which is protected by weighted blocks that keep it free from gillnets. However, the full vaquita refuge area spans 184,100 ha, which remains the species' habitat. With increased financial support for monitoring, greater data collection capacity on the vaquita’s population status could be achieved.
The California sea lion (Zalophus californianus) is a species considered a bio-indicator of the health of the pelagic marine ecosystem, and whose distribution is found throughout the Gulf of California. Regarding the sea lion populations on islands with breeding colonies such as San Pedro Nolasco, San Esteban and San Jorge of the APFF IGC (off the coast of Sonora) and the Isla San Pedro Mártir as a Biosphere Reserve in Sonora, its trend is stable and the population fluctuations it presents are related to changes in sea surface temperature caused by climatic and oceanographic phenomena such as El Niño (ENSO) or the Pacific decadal oscillation (CONANP 2023). There is also an important sea lion rookery on Farallón de San Ignacio Island, with a colony of California sea lions (Zalophus californianus) and also records of the Guadalupe fur seal (Arctophoca philippii townsendi). Both species are listed under SEMARNAT’s NOM-059-2010. Park rangers from the Protected Area conduct biological monitoring at this site.
The property hosts a significant number of different seabird, waterfowl and landbird species and is offers important refuge and breeding sites. Currently, the only stable nesting colony of frigate birds (Fregata magnificens) that exists in the entire Baja California peninsula is the one located in San Gabriel Bay on Espiritu Santo Island. A total of 183 yellow-legged gull nests were recorded on Gaviota, Merito, Ballena, Gallo and Gallina islets with an average of 1.90 eggs per nest and 0.45 chicks per nest. Compared to previous years, nesting was low for both yellow-legged gulls and brown pelicans, with fewer nests, fewer eggs per nest, and therefore fewer chicks during this season. In 2023, the El Niño meteorological phenomenon was one of the five most intense episodes in history, causing sea temperatures in the central and eastern equatorial Pacific to warm significantly (1.5 °C above average). This had effects on plankton productivity (decreases) resulting in unfavourable conditions for zooplankton, larvae, invertebrates and pelagic fish that feed on plankton. In the case of sardines, they move towards colder and deeper waters, thus decreasing the availability of food for seabirds. In 2024, CONANP in collaboration with the University of Guadalajara, conducted the annual nest count on San Pedro Martir Island. Although there were notable variations, the numbers of blue-footed boobies (4,673 individuals in 2021 to 430 in 2024), brown-footed boobies (1331 individuals in 2021 to 260 in 2024) and brown pelicans (996 individuals in 2021 to 602 in 2024) in recent years are only a small fraction of the historical estimate of colony size. It is difficult to determine the causes of colony size reduction in all three species, it may be directly and indirectly related to climate variability events (State Party of Mexico, 2025).
Endemic reptiles and rodents: Annual population data (density) on Sonomar were recorded during 2024 for six species of importance: spiny iguana (Ctenosaura nolascensis), lizard (Uta nolascensis), gecko (Aspidoscelis bacatus) and field mouse (Peromyscus boylii) from San Pedro Nolasco Island and for the iguana (Sauromalus varius), mouse (Peromyscus callatus), mouse (Chaetodipus intermedio) and the rat cambalachera (Neotoma varia). Fluctuations in island population densities could be directly and indirectly related to climate variability events (e.g., El Niño/climate change events), however, the densities recorded are within the threshold of natural variations recorded over more than 10 years of monitoring (State Party of Mexico, 2025). This trend is also observed in other component parts. For example, on San Pedro Martir Island systematic monitoring of huico (Aspidoscelies martyris) and the spotted side lizard (Uta palmeri) indicates that their populations have suffered changes related to temperature and sea level anomalies, due to Niño/Niña events as well as other oceanographic and climatic processes (State Party of Mexico, 2025).
Despite these concerns, to date no species of marine vertebrates or invertebrates have gone extinct, and only the vaquita is today critically threatened. The vast regions of marine coastline that are largely uninhabited on the islands and the Baja California Peninsula provide a "buffer" as a refuge for many of the regions species. Many species that have reached "commercial extinction" have rebounded after cessation of commercial fishing, indicative of resilience in the Gulf's ecosystems (IUCN Consultation, 2025).
Assessment of the current state and trend of World Heritage values
Deteriorating
Large parts of this serial World Heritage site and many key species and habitats remain relatively well preserved. However, despite unprecedented efforts to strengthen law enforcement and surveillance activities, illegal, unregulated and unsustainable fisheries continue and cause serious concern for the protection of the World Heritage values. The lack of decisive progress in stopping the illegal gillnet fishery in the Upper Gulf of California has led to the near-extinction of the vaquita, an endemic porpoise only found in the Gulf of California. The results from acoustic monitoring show that from 2021 to 2023 the negative trend of the population has decreased compared to previous years. In 2023, between 10 and 13 individual vaquitas were recorded, including two calves, suggesting that the species is still reproducing. While marine areas in parts of the World Heritage site remain in good condition, the impacts from climate change are increasingly being felt through temperature and sea level anomalies. During 2023 and 2024 the warming of the sea due to the El Niño event of 2023 had a great impact on the coral fauna and associated invertebrates, causing decreases in most of the functional indicators and environmental services. On the other hand, the ichthyofauna also presented modifications in abundance and specific composition, which lowered its value as an ecosystem provider of social services, although functional diversity remained stable. Despite these concerns there remain a great many coastal and oceanic regions within the Gulf of California that serve as refuges for species threatened elsewhere, and these may serve as recruitment sources over time and fluctuations in ecological conditions elsewhere. Long-term monitoring studies in some component parts show that, although oceanographic phenomena caused temperature variations and population changes—including a coral bleaching episode in Cabo Pulmo—subsequent surveys documented the recovery of the reefs just a few months after the event, demonstrating important resilience.
Additional information
Importance for research,
Contribution to education,
Collection of genetic material
Almost all major oceanographic processes occurring in the planet’s oceans are present in the Gulf of California, which gives it extraordinary importance for the study of marine and coastal processes. The islands are seen as natural laboratories for the examining of speciation, colonization, interaction and adaptation among species; also for geological and evolutionary research (UNEP-WCMC, 2011). The Gulf of California is perhaps where most research is done in marine biota in Mexico but terrestrial studies have been lacking. Mexican and USA institutions make the bulk of scientific research in climatology, oceanography, marine biology, taxonomy, fishery, and ecosystem health assessment. However, long-term studies are scarce and typically of small spatial coverage (Wilder et al., 2025). Part of the problem is the lack of perspective of benefits of systematic monitoring of fishery activities and ecology of terrestrial and marine habitats. Human population growth is beginning to be a serious stressor with about 11 million people living around the Gulf of California. Approximately 2.2 to 2.5 million people live in coastal cities and municipalities directly bordering the Gulf of California on the Mexican side, according to the most recent INEGI census data updated to 2025.
Islands are still uninhabited by permanent humans settlements. This supports the conservation of flora and fauna, but human population around the Gulf of California is increasing rapidly with immigration of national and USA citizens.
Outdoor recreation and tourism
The economic benefits derived from the site include major commercial, artisanal, and recreational fishing, and tourism.
Fishing areas and conservation of fish stocks
The World Heritage site is extremely important for supporting major fisheries in the Gulf of California. However, high concerns remain with regards to both illegal fishing and unsustainable levels of legal fisheries (UNESCO/IUCN, 2017; IWC 2023, 2024).
Climate change: new studies have indicated that changes brought about by climate change will negatively impact shrimp, fish, and cetacean populations within the Gulf of California and will include decreases in productivity and shifts in habitat (Cota-Duran et al., 2021)
Carbon sequestration
An important way to mitigate climate change is throughout the greenhouse gas sequestration. There are two marine ecosystems present in the Gulf of California that can help to greatly achieve: mangroves and (to a limited extent) coral reefs, which fix carbon in the form of tree biomass (trunk, branches and roots) and carbonate skeletons. This carbon is then fixed for decades or even centuries in a biotic structure (UABCS & NIPARAJÁ, 2021).
Note that there is only one true coral reef in the Gulf, at Cabo Pulmo. There are, however, coral communities elsewhere in the southernmost part of the Gulf but these don't store much carbon.
The Gulf of California has an extraordinary importance for the study of marine and coastal processes. The islands are seen as natural laboratories for the examining of speciation, colonization, interaction and adaptation among species and also for geological and evolutionary research. The economic benefits derived from the site include major commercial, artisanal, and recreational fishing, and tourism.
| № | Organization | Brief description of Active Projects | Website |
|---|---|---|---|
| 1 | Fundación Mexicana para la Conservación de la Naturaleza; COBI; PRONATURA Noroeste | Funding of projects by government agencies and NGOs to improve the conservation and management of the property, and support local communities to develop sustainable livelihoods. |
www.fmcn.org
https://cobi.org.mx/. https://pronatura-noroeste.org/en/home-eng/.
|
| 2 | David and Lucile Packard Foundation, The Walton Family Foundation | Funding implementation of the Integrated Program for Marine Protected Areas of the Gulf of California. |
www.packard.org
https://www.waltonfamilyfoundation.org/.
|
| 3 | Conservación del Territorio Insular Mexicano, A.C. (ISLA) | Assessment of the sea cucumber in the marine protected areas in the Bahía de los Angeles area. Working the sport fishing assessment with special attention to totoaba. Assessing local eco-tourism companies to obtain a certification under the NMX-AA-133-SCFI-1996. Eco-tourism Sustainability Norm. |
www.isla.org.mx
|
| 4 | The Slim Foundation (Fundación Slim) | The Slim Foundation is working together with NGOs and government agencies on projects regarding sustainable fishing in the Upper Gulf of California. They are also involved in the integral restoration of islands in the Gulf of California and Baja California Peninsula region as well as environmental education. |
http://fundacioncarlosslim.org/
|
| 5 | Leonardo DiCaprio foundation | Cooperation with Mexican government, Slim Foundation and others in vaquita conservation. |
https://www.leonardodicaprio.org/leonardo-dicaprio-continues-efforts-to-protect-endangered-vaquita/
|
| 6 | Grupo Tortuguero of the Californias | Conservation of marine turtles in the Gulf of California. |
http://www.grupotortuguero.org/
|
| 7 | International Whaling Commission Scientific Committee and WWF Mexico | Design, manage and implement a complete research protocol and business model to measure the economic viability of alternative fishing gear in the Upper Gulf of California to address bycatch of vaquita in gillnet fishery. (1) Data were compiled from multiple experiments that tested new gear for the small-scale shrimp and finfish fleet as alternatives to gillnets. (2) Focus group discussions held with fishermen from the Upper Gulf of California reviewed the data from the tests of alternative fishing gear and noted experimental conditions that were inconsistent with actual fishery operations, such as the number of casts per fishing trip and accurate costs of labours. (3) The focus group discussions allowed adjustment of the data from the experiments to emulate commercial fishery operations and thus more accurately assess the financial viability of alternative fishing gear. (4) In terms of maximizing overall social benefits, an optimal number of fishing permits is estimated, along with a set of policy options for timing of fishing, price premiums, and subsidies. |
https://iwc.int/business-model-to-save-vaquita-from-extinction
|
| 8 | The Scientific Committee of the International Whaling Commission and the Comisión Nacional de Áreas Naturales Protegidas | The acoustic monitoring of vaquita within their core habitat has been ongoing since 2011. The annual surveys are subject to review by a panel of international experts and discussed at the regular meetings of the Scientific Committee of the International Whaling Commission. The latest survey report (year 2023) estimated that 20% decrease in vaquita acoustic were recorded, when compared to the previous year. If acoustic detection rate changes are a proxy of population trend, these new data suggest that the vaquita population is continually decreasing, however, the rate of decrease is at a reduced rate when compared to the time period 2011-18. The acoustic monitoring programme is ongoing and reported to the IWC. |
https://archive.iwc.int/pages/search.php?search=%21collection73&k=
|
| 9 | The Scientific Committee of the International Whaling Commission, WWF-Mexico and the National Fisheries Institute of Mexico (NFIM) | This project assessed the performance of alternative gears to gillnets to try to eliminate vaquita bycatch by allowing fishermen to maintain yield whilst using vaquita safe gear. Particularly, this was done by: (1) monitoring the biomass yield of 15 fish aggregating devices (FADs) installed at known fishing areas in the Upper Gulf of California during winter 2009; (2) assessing the catch efficiency and selectivity of various gear types for a variety of target fishing species around FADs; (3) determining the 'maximum economic yield' for each alternative gear tested. WWF & NFIM 2012. Supporting the assessment of alternative fishing gears for replacing gillnets that cause bycatch of vaquita (Phocoena sinus) at the Upper Gulf of California. Final Report for the International Whaling Commission (IWC), December 21, 2012, 15 pp. |
https://iwc.int/vaquita-aguilar-ramirez-2012-13
|
| 10 | Instituto de Ciencias del Mar y Limnologia of Universidad Nacional Autónoma de México (ICMyL-UNAM), Centro Interdisciplinario de Ciencias Marinas del Instituto Politecnico Nacional (CICIMAR-IPN) | This research programme organized 16 oceanographic cruises from 2005 to 2023 to do acoustic surveys to estimate pelagic biomass and plankton surveys in the central region of the Gulf of California to estimate sardine biomass, jumbo squid abundance, and zooplankton (base pof the pelagic food web). |
No website available
|
| 11 | Scripps Institution Oceanography, Center of Marine Biodiversity Conservation | The Institute of the Americas’ Gulf of California Marine Program (GCMP) works on expanding its research and programming on emerging coastal and marine policy issues of importance to Mexico. Established in 2008 as a research program at Scripps Institution of Oceanography, the GCMP was a part of the University of California Institute of Mexico and the United States (UCMEXUS) based at UC Riverside since 2017. Since its establishment, the GCMP has developed a successful track record of promoting conservation and sustainable management through multidisciplinary approaches, focusing on generating, analyzing and sharing scientific information to key stakeholders and policymakers involved in shaping coastal and marine policy in Mexico. |
https://iamericas.org/the-gulf-of-california-marine-program/
|
References
| № | References |
|---|---|
| 1 |
Arreguin-Sanchez, F, Arreguín-Sánchez, F, del Monte-Luna, P, Zetina-Rejón, MJ, Albáñez-Lucero, MO. 2017. The Gulf of California Large Marine Ecosystem: Fisheries and other natural resources. Environmental development 22: 71-77. http://dx.doi.org/10.1016/j.envdev.2017.03.002
|
| 2 |
Barraza-Guardado, R. H., Arreola-Lizárraga, J. A., López-Torres, M. A., Casillas-Hernández, R., Miranda-Baeza, A., Magallón-Barrajas, F., & Ibarra-Gámez, C. (2013). Effluents of shrimp farms and its influence on the coastal ecosystems of Bahía de Kino, Mexico. The Scientific World Journal, 2013(1), 306370.
|
| 3 |
Barraza-Guardado, R. H., Martínez-Córdova, L. R., Enríquez-Ocaña, L. F., Martínez-Porchas, M., Miranda-Baeza, A., & Porchas-Cornejo, M. A. (2014). Effect of shrimp farm effluent on water and sediment quality parameters off the coast of Sonora, Mexico. Ciencias Marinas, 40(4), 221-235.
|
| 4 |
Barraza-Guardado, RH, Arreola-Lizárraga, JA, López-Torres, MA, et al., “Effluents of Shrimp Farms and Its Influence on the Coastal Ecosystems of Bahía de Kino, Mexico,” The Scientific World Journal, vol. 2013, Article ID 306370, 8 pages, 2013. doi:10.1155/2013/306370
|
| 5 |
Bath, P., and Putney, A. (2010). Final Independent Evaluation of SINAP 2, Mexico. GEF/World Bank.
|
| 6 |
CONANP, 2006. Golfo de California, Estrategia del Subprograma,2006–2011
|
| 7 |
CONANP. (2021). Estudio de Límite de Cambio Aceptable para regular actividades turístico recreativas (isla San Pedro Martir). INFORME FINAL. PROREST/ETM/8/2021. Universidad Autónoma de Baja California Sur.
|
| 8 |
CONANP. (2022). Estudio de Límite de Cambio Aceptable para regular actividades turístico recreativas (isla Tiburón). INFORME FINAL. PROREST/ETM/5/2022. Universidad Autónoma de Baja California Sur.
|
| 9 |
CONANP. (2023). Monitoreo regional de Lobo marino de California (Zalophus californianus) en las islas reproductoras del APFF-IGC y RB-ISPM Sonora. Reporte interno.
|
| 10 |
Cardoso-Mohedano, J. G., Páez-Osuna, F., Amezcua-Martínez, F., Ruiz-Fernández, A. C., Ramírez-Reséndiz, G., & Sanchez-Cabeza, J. A. (2016). Combined environmental stress from shrimp farm and dredging releases in a subtropical coastal lagoon (SE Gulf of California). Marine pollution bulletin, 104(1-2), 83-91.
|
| 11 |
Comisión Nacional de Áreas Naturales Protegidas, 2016. Fichas de evaluación ecológica de áreas naturales protegidas del noroeste de México. 240 pp.
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