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June 2002

ESIG research sheds light on endangered salmon

When ESIG scientist Kathy Miller was an economics graduate student in Seattle, she noticed a puzzling phenomenon. Salmon prices dropped during the 1982–83 El Niño—even though local populations of the fish had declined. Upon further investigation, she found that the market had been flooded with Alaskan salmon, overwhelming the effects of faltering local harvests.
Economist Kathy Miller studies the policy implications of climate variability’s effects on salmon populations. (Photo by Carlye Calvin)

Kathy has continued to study the effects of climate variability on salmon populations and the resulting policy implications since coming to NCAR in 1985. She’s discovered that such an inverse fluctuation between Alaskan and Pacific Northwest salmon stocks is not a fluke. In fact, she warns that fisheries managers need to understand the effects of climate variability on populations of salmon and other fish in order to avoid depleting valuable species.

"The basic lesson is that nature is dynamic, and if you approach resources management without understanding that, you’re going to be in trouble and endanger the resource," she warns.

Until 1999, fisheries managers in the United States and Canada found themselves in a protracted and costly dispute over salmon harvests, in part because they failed to account for the effects of climate variability. The salmon hatch in freshwater rivers in the western United States and Canada, then intermingle in the oceans before returning to their native rivers to spawn and die. Therefore, each fleet historically harvested a mix of domestic and foreign fish. The two nations have a long history of negotiating salmon harvest amounts.

When Canada and the United States negotiated the 1985 Pacific Salmon Treaty, they thought the agreement would encourage conservation while balancing each nation’s interceptions of the other’s salmon stocks. However, the agreement relied upon overly optimistic assumptions about salmon populations that failed to take into account the possible effects of changes in the ocean environment.

Twenty years of warming

Beginning in the mid-1970s, a 20-year period of warmer Pacific coastal waters caused salmon populations off Oregon and Washington to diminish as feeding conditions deteriorated and juvenile salmon fell prey to southern species that moved into the area, such as jack mackerel. But the same warming trend bolstered the populations of salmon that originated in Alaska, where the productivity of salmon feeding grounds increased dramatically.

As a result, Alaskan fishing fleets increased their catch—even in areas where British Columbian and Alaskan fish intermingled. Canadian fishing fleets also fished harder, but they couldn’t reach their limits because of declining coho and chinook stocks in Canadian waters. The salmon populations along the U.S. West Coast, already diminished because of the warmer water, came under further pressure because many of those fish ended up in the nets of Canadian fishing boats. Cooperation between the fleets collapsed, and competitive tactics on both sides created ill will and further endangered weakened stocks.

Capping several years of turmoil, the United States and Canada reached a new salmon agreement in 1999. The new agreement seeks to base catch limits on the abundance of each salmon species in each fishing area. But it came about only after the populations of several West Coast salmon species had become so depleted that the United States took steps to protect them under the Endangered Species Act.

Kathy and four colleagues published a paper last October (Canadian-American Public Policy Occasional Paper #47, University of Maine), in which they chronicled the Pacific salmon dispute and drew lessons for the future management of international fisheries. They explored the issues from the perspectives of international law, game theory, and marine resource management, giving particular attention to the impacts of climate variability. The researchers concluded that the 1999 salmon agreement will be effective only if the United States and Canada monitor salmon populations closely, factor in a margin of error for imperfect forecasts, and continue to develop more flexible arrangements for sharing the benefits of the fishery.

Kathy says that understanding the natural dynamics is just one part of the picture. "You also need to understand what drives the competitive behavior of the harvesters and how those motivations can be controlled to allow sustainable resource use," she says. "This is the type of research that really needs to be expanded. A lot of the world’s fishing resources are vastly overexploited. Many of the destructive practices can be traced to a competitive race to exploit shared fish resources, with no attention given to the risk that intensive harvesting may compound natural fluctuations in the stocks." • David Hosansky

As salmon return to their native rivers to spawn, they cross political boundaries and are caught by the competing fishing fleets of Alaska, British Columbia, Washington, and Oregon. A 1999 fishing treaty attempts to apportion fishing rights, taking into account the disparate effects of climate variability on various species of salmon.
On the Web:

Some of Kathy’s publications on this topic are available online.

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UCAR > Communications > Staff Notes Monthly > June 2002 Search

Edited by David Hosansky, hosansky@ucar.edu
Prepared for the Web by Carlye Calvin
Last revised: Wed June 26 17:08:40 MST 2001