Global curbs on overfishing are beginning to work
Australian Beth Fulton, a fishery ecosystem scientist from the CSIRO Wealth from Oceans Flagship, was among an international team of 19 co-authors of a report on a two-year study, led by US scientists Dr Boris Worm of Dalhousie University and Dr Ray Hilborn of the University of Washington.
The study shows that steps taken to curb overfishing are beginning to succeed in five of the 10 large marine ecosystems they examined. The paper, which appears in the 31 July issue of the journal Science, provides new hope for rebuilding troubled fisheries.
The study had two goals: to examine current trends in fish abundance and exploitation rates (the proportion of fish taken out of the sea) and to identify which tools managers have applied in their efforts to rebuild depleted fish stocks.
The work is a significant leap forward because it reveals that the rate of fishing has been reduced in several regions around the world, resulting in some stock recovery. Moreover, it bolsters the case that sound management can contribute to the rebuilding of fisheries elsewhere.
It is ‘good news’ for several regions in the US, Iceland and New Zealand.
“These highly managed ecosystems are improving,” says Dr Hilborn. “Yet there is still a long way to go: of all fish stocks that we examined 63 per cent remained below target and still needed to be rebuilt.”
According to Dr Worm, there is still a troubling trend of increasing stock collapse across all regions.
“But this paper shows that our oceans are not a lost cause,” Dr Worm says.
“The encouraging result is that the exploitation rate – the ultimate driver of depletion and collapse – is decreasing in half of the 10 systems we examined in detail. This means that management in those areas is setting the stage for ecological and economic recovery. It’s only a start but it gives me hope that we have the ability to bring overfishing under control.”
The authors caution that their analysis is mostly confined to intensively managed fisheries in developed countries, where scientific data on fish abundance is collected. They also point out that some excess fishing effort is simply displaced to countries with weaker laws and enforcement capacity.
Dr Fulton used the ecosystem models Atlantis and Ecosim to analyse ecosystem recovery in 31 fisheries worldwide, 10 in detail, including Australia’s Southern and Eastern Scalefish and Shark Fishery.
She says a combination of management measures has been adopted in Australia’s commonwealth fisheries in the past decade to reduce pressures on fishery ecosystems.
These intensive efforts involved cooperation between fishery scientists, managers and industry. Management measures included catch quotas coupled with strategically placed fishing closures, ocean zoning, selective fishing gear, community co-management and economic incentives (such as individual transferable quotas).
“Exploitation rates have more than halved since the early 1990s,” Dr Fulton says. “This means that management is setting the stage for ecological and economic recovery.
“As a result we are seeing recovery in overall ecosystem structure, even if some species aren’t fully recovered yet.
“But we can’t rest on our laurels. Management methods need to be tailored to particular fisheries and regions and also need to change through time as the system changes.”
Dr Fulton says surveys conducted up to the mid-1990s showed signs of recovery in ecosystem structure in the North West Shelf region of Western Australia, although some species groups had not fully recovered.