A decade-long program to protect Australian sea lions from a damaging fishing method known as gillnetting has borne fruit off South Australia with new research revealing captures in a Commonwealth fishery have been reduced by 98%.
The Australian Marine Conservation Society (AMCS) and Humane Society International (HSI) worked with government, scientists and fishers to instigate a management strategy after a South Australian Research and Development Institute (SARDI) report published in 2010 found up to 256 Australian sea lions were killed in gillnets in the Commonwealth managed Gillnet Hook and Trap (GHAT) Fishery every year.
Key elements of the Australian Sea Lion Management Strategy, introduced a decade ago, included gillnet fishing exclusion zones around all breeding colonies, cameras on fishing boats and the introduction of closures in parts of the fishery if a certain number of sea lions were caught. This incentivised fishers to switch to the less damaging longline method to catch their target shark species.
AMCS and HSI are now calling for similar measures to be fast-tracked in a Western Australian fishery to assist recovery of sea lions there.
AMCS campaign manager Tooni Mahto said:
"The number of sea lions being killed over a decade ago was too high for sea lion populations to withstand. Commercial fishers were also failing to report to authorities how many sea lions were being killed.
"The results in this study show what can be achieved for our oceans if all stakeholders work together.
HSI senior campaign manager Alexia Wellbelove said:
"Bycatch in fisheries is a recognised cause in the decline of Australian sea lions. The establishment of the Australian sea lion management strategy was no easy task, but this study is evidence that the strategy is working and the implementation of management measures can be highly effective."
"Australian sea lions are unique to Australia, and unique in their biology. The tough decisions made in 2010 to implement the management strategy will in time lead to recovery of Australian sea lion populations."
Professor Simon Goldsworthy, Lead author of the Assessment of Australian Sea Lion Bycatch Mortality in a Gillnet Fishery, and Implementation and Evaluation of an Effective Mitigation Strategy paper, and principal scientist the South Australian Research and Development Institute (SARDI), the research arm of the Department of Primary Industries and Regions in South Australia (PIRSA) said:
"Since the implementation of the Strategy a decade ago, we estimate there has been a 98% reduction in sea lion bycatch mortality in the gillnet fishery, and the precipitous declines in sea lion numbers that we observed in the decades prior to management, have largely been halted," Professor Goldsworthy said.
"Not only has bycatch mortality been reduced to levels that should enable sea lion populations to recover, there has been an almost complete transition from gillnets to longlines in the sea lion management zone and fishing catches have returned to pre-bycatch management levels. In the context of managing marine mammal bycatch globally, it is an extraordinary outcome.
"This kind of conservation and management outcome is extremely rare and sets an important precedent both nationally and internationally," he said.
In light of this study AMCS and HSI consider it essential to maintain the Australian sea lion management strategy in the waters off SA. It is now essential that the WA shark fishery, which has committed to introducing certain measures including increased monitoring by 2024, strengthen these measures before their introduction next year.
Background
Australian sea lion (Neophoca cinerea) is a federally endangered species, whose populations off South Australia (SA) have been subject to bycatch in the GHAT fishery targeting sharks since the 1960s, to feed the Australian appetite for what's commonly known as 'flake' at the fish and chip shop.
Sea lion populations off SA have declined by 67% over the last four decades. In 2020 they were uplisted to Endangered under Australia's environment laws – the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). Females are extremely philopatric meaning they return to the same rookery, or breeding colony, to reproduce. Consequently, each rookery is its own subpopulation, and if only a few females die it can permanently wipe out an entire colony.
Gillnets are hung vertically in the sea to entangle fish but they are invisible and deadly for endangered marine wildlife like sea lions unless they are constantly attended and deployed in the water for only a short time.
