The many populations of sockeye salmon in Bristol Bay, Alaska act like a diversified portfolio of investments, buffering fisheries and incomes from the ups and downs of particular stocks. Sockeye salmon are one of the most valuable fisheries in the U.S., and since 1950, more than 60% of that value has come from Bristol Bay. A new study in the June 3 issue of Nature quantifies, for the first time, just how much depends on this "portfolio effect." Without its current population diversity, the Bristol Bay sockeye fishery would close ten times more frequently once every two to three years rather than once every 25 years.
The study, by scientists at the University of Washington, draws on five decades of data and provides the first solid evidence that population diversity within a species plays a key role in maintaining stable fisheries.
"We believe this new evidence is a game-changer for managing species and entire ecosystems," says lead author Daniel Schindler, an ecologist at the University of Washington. "Population diversity of species is often overlooked by managers and conservationists. Yet in general, current rates of population loss are probably a thousand times higher than species loss."
The authors argue that, in order to maintain the steady flow of fish and other ecosystem services people depend upon, managers will need to put an explicit priority on preserving population diversity within species. Such strategies require aggressive protection of the habitat networks that ultimately generate and maintain population diversity. Both approaches will become increasingly important as a first line of defense against climate change.
"Part of it is understanding history and having the discipline not to chase the hottest stock of the day," says co-author Ray Hilborn, also at the University of Washington. "We have to maintain a range of productive elements - a broad range of stocks."
With a landed value of more th
|Contact: Liz Neeley|
Communication Partnership for Science and the Sea