Climatic Trends and Fluctuations in Yield of Marine Fisheries of the Northeast Pacific

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Abstract
Mean annual air temperature at San Francisco, California, New Westminster and Masset, British Columbia, all had a rising trend from 1920 to 1940, then declined to 1950. Amplitude was greatest at Masset, least at San Francisco. The 20-years' rise is similar to the story in the North Atlantic ocean, but the recent decline has no parallel there. Prior to 1920 there were considerable differences among the above three stations. Mean annual ocean temperature at Nanaimo, B.C., is similar to air temperature at New Westminster since 1915. "Winter" ocean temperatures (February–April) show similar but not identical trends, and are thought to best represent conditions at the time eggs and larvae of most commercial bottom fishes are in the water.Suggestive short-term correlations have been observed as follows: 1. a positive correlation between winter temperature and abundance of brill 6 years later; 2. a negative correlation between winter temperature and rock sole abundance 5 years later; 3. a negative correlation between winter temperature and strength of year-classes in lemon sole. Over a longer period, there is much resemblance between the temperature history since 1910 and the abundance of halibut broods, as indicated by catch per unit effort 10 years later (southern grounds) or 12 years later (Western grounds). The relationship is positive, and for western grounds is similar even in details. Over a somewhat shorter period, blackcod abundance has varied inversely with winter temperature. Marked changes in abundance and distribution of true (grey) cod since about 1900 cannot be related to temperature series available.

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