Scientists have joined forces in a groundbreaking assessment on the status of marine fisheries and ecosystems.
The two-year study, led by Boris Worm of Dalhousie University and Ray Hilborn of the University of Washington and including an international team of 19 co-authors, shows that steps taken to curb overfishing are beginning to succeed in five of the 10 large marine ecosystems that they examined.
The paper, which appears in the July 31 issue of the journal Science, provides new hope for rebuilding troubled fisheries. The research was supported by the National Science Foundation (NSF) through its National Center for Ecological Analysis and Synthesis (NCEAS) in Santa Barbara, Calif.
"This is a landmark effort to resolve long-standing and seemingly contradictory conclusions based on the same available data," said Henry Gholz, NSF program director for NCEAS. "It demonstrates the power of synthesis."
Adds David Garrison, director of NSF's biological oceanography program, which funds Hilborn's research, "The results of this study provide hope that, with an increased understanding of ecosystem dynamics and development of creative management solutions, fisheries may be saved."
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, the scientists say, because it reveals that the rate of fishing has been reduced in several regions around the world, resulting in some stock recovery. It bolsters the case that sound management can contribute to the rebuilding of fisheries elsewhere.
It's good news for several regions in the U.S., Iceland and New Zealand. "These highly managed ecosystems are improving" says Hilborn. "Yet there is still a long way to go: of all fish stocks we examined, 63 percent remained below target and still needed to be rebuilt."
"Across all regions we are still seeing a troubling trend of increasing stock collapse," adds Worm. "But this paper shows that our oceans are not a lost cause.
"The encouraging result is that the exploitation rate--the ultimate driver of depletion and collapse--is decreasing in half of the ten systems we examined in detail. Management in those areas is setting the stage for ecological and economic recovery. It's only a start--but it gives hope that we have the ability to bring overfishing under control."
The authors caution that their analysis was 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.
While most of the fisheries that showed improvement are managed by a few wealthy nations, there are some notable exceptions.
In Kenya, for example, scientists, managers and local communities have teamed up to close some key areas to fishing and restrict certain types of fishing gear.
This led to an increase in the size and amount of fish available, and a consequent increase in fishers' incomes. "These successes are local--but they are inspiring others to follow suit," says Tim McClanahan of the Wildlife Conservation Society in Kenya.
"We know that more fish can be harvested with less fishing effort and less impact on the environment, if we first slow down and allow overfished populations to rebuild," adds co-author Jeremy Collie from the University of Rhode Island.
"Scientists and managers in places as different as Iceland and Kenya have been able to reduce overfishing and rebuild fish populations despite serious challenges."
The authors emphasize that a range of management solutions are available to help rebuild fish stocks.
They found that a combination of approaches, such as catch quotas and community management, coupled with strategically placed fishing closures, ocean zoning, selective fishing gear and economic incentives, offer promise for restoring fisheries and ecosystems.