Marine ecology experts are calling for an urgent change to global fisheries management after the publication of data showing an unprecedented decline in fish populations in Australian waters.
New research by scientists at the University of Tasmania (UTas) and University of Technology Sydney (UTS) indicate numbers of large fished species have decreased by about a third over the past decade around Australia.
Several pressures, including climate change, have triggered this decline but the main cause appears to be excessive fishing, the researchers say in findings published in Aquatic Conservation.
The researchers conclude fishery management urgently needs to take better account of ecological issues and uncertainties when setting allowable catch levels in commercial and recreational fisheries.
UTas Professor Graham Edgar said the use of underwater surveys conducted as part of the Reef Life Survey, a global citizen science program, combined with research diver surveys, allowed the first fishery-independent assessment of the size and abundance of coastal fish species around the Australian continent.
“We found consistent population declines among many popular commercial and recreational fishes, including in marine parks that allowed limited fishing, while numbers increased within no-fishing reserves,” he said.
Professor Edgar and his research co-author, UTS Professor Trevor Ward, said Australia and other countries would not be able to meet international agreements on marine ecosystems and fisheries without major changes in marine ecosystem management, including the management of commercial fisheries.
“Effective recovery of fish populations, so that catch can be doubled from the present very low levels, cannot occur without major change to business as usual,” Professor Edgar said.
The authors said marine reserves are a well-understood management option that is available “off the shelf”. Reserves offer the least-cost high-impact intervention with benefits to both ecosystems and to fisheries.
“No-fishing marine reserves are well known to be efficient and effective mechanisms for the ecological protection of fish populations,” Professor Ward said.
“There is little doubt that in Australian waters, with proper design and placement, marine reserves would assist fish population recovery. Eventually this would lead to increased catches for all fishers.”
Professor Ward said few sanctuary areas exist to protect fishes in the critical locations most heavily affected by fishing.
UTS Professor of Marine Biology David Booth, who was not involved in this study, said the study results are a “real wake-up call for our nation”.
“As world leaders in marine diversity and ecosystem management through our earlier marine parks and fisheries programs, we now have clear evidence of the need for urgent improvements. We need to apply all our capacity to work together to correct the fish decline and recover fishing.
“Australia’s capacity across universities, agencies and industries for adaptive and effective management in such matters is unparalleled. The world awaits our leadership in this issue of ocean stewardship, and our recognition and implementation of equitable and effective solutions to these matters, which afflict almost all nations and their oceans,” Professor Booth said.
Key points from the study include:
- The study compared continental trends in fisheries catches with underwater reef monitoring data for 533 sites repeatedly surveyed around Australia through the period 2005-15
- Populations of exploited fishes generally rose within fully protected marine reserves and declined outside the reserves and in marine park zones with some fishing allowed
- Unexploited species showed little difference in population trends within or outside reserves
- The biomass of large fishes observed on underwater surveys showed a 36% decline on fished reefs, and 18% declined in marine park zones that allow limited fishing
- Overall, large fish biomass showed a slight rising trend in no‐fishing marine reserves
- The implementation of a relatively small number of solutions could make substantial progress towards addressing issues with current fisheries management practices