Climate Change and Alaska Fishery Management.

• Author: POHL, JOHN

Researches are looking at regime shifts to explain how climate changes affect the state's fisheries over the long-term.

The Alaska fishing industry is learning firsthand about ecosystem change and changing fisheries, and the teacher is hard to ignore: the climate of the North Pacific. Scientists now believe that besides dramatic yearly changes in climate, like those exhibited by El Nino, there are also interdecadal climatic cycles, where regimes of climate and ocean characteristics flip flop from one cycle to another. When these climate shifts occur, they have the potential to disturb and change coastal eco-systems, affecting fisheries and jobs all around the Pacific Rim. In light of this, scientists are studying the regime shifts and seeking ways to improve fisheries management.

The Regime Shift

"There is just no question that something large happened both in the atmosphere and the ocean in many places in the North Pacific in the late 1970s," says Dr. John McGowan, a research professor of oceanography at Scripps Institution of Oceanography in California. "Not all parts of the ocean responded in a similar way, but they did respond at the same time."

Intrigued by the occurrence, researchers coined the term "regime shift" for the phenomena. Although it has no inclusive definition, a regime shift does have certain aspects that scientists agree upon. A regime is the characteristic behavior of a natural phenomenon, such as sea surface temperature or sea surface pressure, for example. A shift is a change from one characteristic behavior to another, occurring over a shorter time period relative to the regime's durability. A regime may span a decade or more while the shift occurs in approximately a year.

Fisheries scientists already study the effects of annual changes in weather and physical oceanographic conditions so they can make year-to-year adjustments in management of specific fisheries. Until recently, they focused on yearly changes over geographic areas that encompassed the range of important commercial species. For example, the article "The Management of Fisheries and Marine Ecosystems," published in the journal Science volume 277 (1997), notes that "coupled changes in the atmosphere and the ocean occur irregularly every few years to create ENSO (El Nino-Southern Oscillation) conditions in the Pacific. These conditions involve warmer waters over a range of latitudes in the Eastern Pacific, which are accompanied by changes in coastal...