Hope for Over-harvested Fisheries

Bren associate professor of environmental economics Christopher Costello is a co-author of a paper titled "Rebuilding Global Fisheries," which appears in the July 31 issue of the journal Science and indicates favorable trends in several fisheries that have instituted some form of catch-shares management.

While "63 percent of assessed fish stocks worldwide still require rebuilding," according to the researchers on the two-year study based at UC Santa Barbara, they found that "in 5 of 10 well-studied ecosystems, the average exploitation rate has recently declined and is now at or below the rate predicted to achieve maximum sustainable yield for seven systems."

The authors caution that their analysis was confined mostly to intensively managed fisheries in developed countries such as the U.S., New Zealand, and Iceland, and that reversing overfishing trends is especially difficult in developing countries where economic alternatives to fishing do not exist and the local population is therefore unable to sustain the losses to income that can result from restrictive management. 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 note that a variety of diverse management tools exist to meet fisheries and conservation objectives, including can be achieved by merging diverse management actions, including catch restrictions, gear modification, and closed areas, which must be selected and individualized according to the local context.

This new study is a follow-up to a 2006 paper by co-principal investigator Boris Worm of Dalhousie University in which he suggested that if current trends continue, the world's fisheries could be wiped out by mid-century. That paper led to a public disagreement between Worm and co-principal investigator of this study Ray Hilborn, of the University of Washington. Through subsequent discussions, however, the two scientists recognized that they shared a purpose and decided to collaborate on a more detailed assessment of the world's fisheries, which brought together many of the world's leading fisheries scientists and ecologists for the study, conducted by a series of working groups at the National Center for Ecological Analysis and Synthesis (NCEAS) at UCSB.

Read the complete paper.