Îles Heard et McDonald

There are low levels of disturbance to non-breeding seabirds and marine mammals; potential higher disturbance to breeding seabird populations is associated with tourism, research, fisheries/customs enforcement activities as these activities overlap with seabird and marine mammal breeding seasons. There have been no recent commercial tourism visits (2015 - 2024) but an unknown number and frequency of visits associated with fisheries inspections and Customs monitoring in EEZ, some of which are known to land on Heard Island (IUCN Consultation, 2020b; IUCN Consultation, 2024).

Visitation brings the potential for introduction of alien species; the worst-case scenario of which would be the introduction of rodents or plants which have a high potential of being invasive, there is also the potential for invertebrate introduction (Houghton et al., 2019). Biosecurity guidelines are in place for authorised visits to mitigate this threat (Australian Government, 2014) but are challenging to enforce. Private vessels are known to visit Heard Island (and likely to visit McDonald Islands) with no biosecurity assessment, implementation or enforcement. Sailing vessels depart from South Africa and the South African and/or French sub-antarctic islands en route to Heard Island and are considered a high biosecurity risk (IUCN Consultation, 2020b). Heard Island possesses a relatively low number of non-native species overall (Australian Government, 2014). Poa annua, a grass species that originated in Europe and is now found on all major subantarctic island groups, was discovered at the edge of Heard Island’s Winston Lagoon in the austral summer of 1986-87. Seabirds probably transported Poa annua to Heard Island from nearby Îles Kerguelen and is considered a non-native species on Heard Island. Leptinella plumosa, a daisy native to the subantarctic region, was discovered at Heard Island’s Paddick Valley in 2004 (Whinam & Shaw, 2018). Heard Island possesses only three non-native animal species: the worm Dendrodrilus rubidus, the thrip Apterothrips apteris and the mite Tyrophagus putrescentiae (Australian Government, 2014). Although Heard Island has been exposed to other non-native animal species in the past, there is no evidence of their current existence. The chances of alien species becoming established on the Islands is however likely to increase as the climate continues to warm, and through the increase in marine pollution carrying non-native species (Bax et al., 2003).

Registered tourism to the islands is very low, and requires a permit under the Environment Protection and Management Ordinance 1987 (EPMO) made under the Heard Island and McDonald Islands Act 1953. Low levels of disturbance to seabirds and marine mammals are associated with commercial tourism, research expeditions and fisheries/customs enforcement staff while ashore. Vessels must abide by approach guidelines for cetaceans prescribed under the EPBC Act 1999, and no discharge of ballast water, oil, oily waste, or sludge is permitted inside the site. The apparent infrequency of visitors and strict regulation of known activities mean the expected risk of significant negative impacts to the conservation values from human visitors is very low. However, if these visits occur without appropriate biosecurity and quarantine the environmental consequences would be dire (IUCN Consultation, 2020c).

No assessments are available of the effects of fishing on geological processes and generally the impact of fishing is considered low for the World Heritage values. Nevertheless, the impact on migratory species, seabird and marine mammals is considered high although preferred fishing grounds occur outside the site (Crawford et al., 2017; AFMA, 2020; Patterson & Curtotti, 2023). Illegal fisheries are unlikely to occur in the world heritage site because the favoured target species occur in greater abundances elsewhere in the Territory. While incidental mortality of seabirds and seals breeding at the site is rare in the legal fisheries, IUU fishing may occur at any time of the year and inflict high levels of mortality on threatened and endangered species in critical reproductive periods. The last recorded incidence of an IUU fishing vessel in the Heard Island and McDonald Islands Exclusive Economic Zone was more than a decade ago (IUCN Consultation, 2020a). The HIMI fishery is the only fishery in the CCAMLR area that uses bottom trawling methods. The most recent fishery assessment showed that estimated biomass of Patagonian toothfish was 45% of unfished levels, which is below the long term reference level of 50%. Further declines are projected under the recommended TAC before a slow recovery to the reference level at the end of the 35yr period. However, 'there are concerns that the levels of recruitment used in the 35 year projection period have not been achieved in the past 20 years in the stock assessment. Also the projection period is reset to 35 years at each assessment, which could result in the stocks always remining below the expected mean level of 50%. Constable et al. (2024) further discussed the possible impact of climate change on recruitment and the need for a review of the suitability of management models and the decision rules that are based on an assumption of stable recruitment. A major impact of the toothfish and icefish fishery is a large bycatch of numerous protected species as well as skates, sharks and rays. Skates are the most frequent bycatch. Constable et al. (2024) flagged concerns that there is a lack of independent assessment for deepwater skate bycatch.

A research station was occupied on Heard Island between 1947 – 1954, then abandoned; during subsequent short-term periods of occupation other structures were erected (primarily temporary accommodation). Almost all materials were left in situ and some older structures have deteriorated from lack of maintenance and from exposure to the elements (Green, 2006; Munro, 2006). The majority of derelict infrastructure and materials from the 1940s - 1970s was removed during visits in the 2000s and 1990s, some materials remain scattered over the landscape downwind of Atlas Cove (NW Heard Island). Flying debris can impact wildlife such as penguins and seals if debris is large enough (IUCN Consultation, 2017). Sealing artefacts at Spit Bay (try pots) continue to deteriorate due to weathering and animal disturbance (IUCN Consultation, 2020c).

Poa annua is a non-native species established, and now expanding, on ice-free areas on the eastern and southeastern ice-free areas of Heard Island (where there is a significantly milder climate than western areas), which are occurring more frequently under climate change. Competition with native vegetation and potential interference with natural processes of colonisation by native plant species is occurring (Scott and Kirkpatrick, 2005; Schortemeyer et al., 2015). Elsewhere in the sub-Antarctic and Antarctic once established Poa annua spreads in extent. There are no other known non-native plant species established on Heard island. However there may be new arrivals or remote populations that have gone undetected. There has not been a comprehensive survey of the terrestrial ecosystem on Heard Island since 2003/4; but a management visit is planned for 2025-6 (IUCN Consultation, 2024).

Plastics regularly wash up on Heard Island beaches (Schmieder, 2016). Plastic debris is common on the foreshores of the site (Eriksson et al., 2012). Data shows 94% marine debris surveyed was plastic, including plastic bottles and lost/discarded fishing gear. Fisheries related debris accounted for 40% of all artefacts on Heard Island (CCAMLR, 1989). There are documented reports of wildlife entanglement, plastic ingestion by, and of oiling of seabirds at Heard Island (Auman et al., 2004). Smaller petrels feed by capturing prey at the surface and can mistake plastic particles as prey. Three reports of seabirds ashore with oil on feathers, evidence indicates oiling at sea rather than onshore (Woehler, 2006). At Heard Island two Pachyptila desolata (Antarctic prions) were found to have ingested plastic fragments which are also documented in seal faeces and in stomach samples from birds. At present, there are no ongoing assessments of marine pollution. The fisheries have greatly expanded in the region, including outside the Territory, and are know to lose large quantities of fishing gear. No assessments have been undertaken to determine whether plastic pollution and feeding disruption is increasing. This is regarded as a large threat for colonies elsewhere in the world that have been assessed for feeding impacts by plastic pollution. This is a potentially high risk until onshore assessments have been undertaken including annual monitoring to properly determine origin and rates of marine plastic pollution. Globally, marine pollution (debris, large solid objects, chemicals) is increasing and an emerging issue for the Southern Ocean (Grant et al 2021; Morley et al 2020). Containers, such as fuel drums and gas cylinders that have washed up on Heard Island as marine debris, may rust and leak contents causing local contamination (IUCN Consultation, 2017). The impacts of chemical pollution on site needs to be assessed.

Climate change and sea level rise poses a significant threat to World Heritage values of the site. The warming temperature of the Southern Ocean and changes in weather patterns is causing significant changes to the subantarctic environment. Sea surface temperatures have increased by 0.6 -1°C over only 1-2 decades (Constable et al., 2024), marine heatwaves have seen an increase by 30-35 days, sea level rise has increased 4-8cm, and ocean acidification by 30% (Donoghue et al., 2021), while land temperatures have increased by 0.8-1.1°C (Constable et al., 2024). These increased temperatures are having a significant effect on the Islands fast-moving glaciers. Glacial retreat has reduced the glaciated area of Heard Island from 80% in the 1940s to around 64% in 2014 (Donoghue et al., 2021). This is impacting eastern leeward glaciers at greater rates than those on the windward side, where Brown Glacier and Stephenson glaciers have declined by around 50% (Donoghue et al., 2021). Climate change and sea level rise poses a significant threat to World Heritage values of the site. Rapid and accelerating glacial retreat is leading to the formation of new waterways (specifically lagoons and pro-glacial lakes) and is exposing new land for flora and fauna colonisation. The eastern part of Heard Island (Spit Bay region) has been isolated from its feeding glacier and thus water supply to support ice-cored moraines that melt to irrigate vegetation, especially the cushion plants and the pool complex wetland, has now been cut (CSIRO et al, 2022). Coupled with known föhn winds that generate high temperatures, drought conditions are likely to occur in locations around the island. Keystone species such as the cushion plant, Azorella selago and also bryophytes, are potentially highly susceptible to restricted water conditions and lower humidity (Bergstrom et al., 2015). The alien grass species Poa annua may be displacing native vegetation on Heard Island, especially colonising newly deglaciated landscapes, which are increasing in frequency and area under climate change.

Some clean-up efforts were undertaken in the 1980s and 2000s to remove hazardous materials left in situ at Atlas Cove when the station was abandoned in 1954, such as asbestos, old fuel drums, building materials, broken glass etc. All diesel fuel was burnt and LPG cylinders were vented to minimise pollution and explosive risks in the 1980s. Asbestos is still present locally in small quantities (IUCN Consultation, 2020b). Contamination of soils by fuel can impact local biota. Glass and rubbish previously buried in situ continues to be exposed by storm surges, posing a physical risk to local wildlife traversing the area.