Abstract
A principal component analysis reveals that Pacific salmon catches in
Alaska have varied inversely with catches from the United States West Coast
during the past 70 years. If variations in catch reflect variations in
salmon production, then results of our analysis suggest that the spatial
and temporal characteristics of this "inverse" catch/production pattern
are related to climate forcing associated with the Pacific Decadal Oscillation,
a recurring pattern of pan-Pacific atmosphere-ocean variability. Temporally,
both the physical and biological variability are best characterized as
alternating 20- to 30-year-long regimes punctuated by abrupt reversals.
From 1977 to the early 1990s, ocean conditions have generally favored
Alaska stocks and disfavored West Coast stocks. Unfavorable ocean conditions
are likely confounding recent management efforts focused on increasing
West Coast Pacific salmon production. Recovery of at-risk (threatened and
endangered) stocks may await the next reversal of the Pacific Decadal Oscillation.
Managers should continue to limit harvests, improve hatchery practices
and restore freshwater and estuarine habitats to protect these populations
during periods of poor ocean productivity.
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