CLIMATE AND EXCEPTIONAL FISH PRODUCTION OFF THE WEST-COAST OF NORTH-AMERICA

From 1976 to 1978 there was a change in the climate over the North Pacific Ocean. The Aleutian Low intensified and there was a warming of the sea surface adjacent to North America and a cooling offshore. Associated with this change was a period of exceptional fish production. Strong year classes and above-average survival occurred for many commercially important species all along the west coast of Canada and the United States. Trends in total salmon catches increased primarily from increased salmon production in Alaska. Some stocks of maturing pink (Oncorhynchus gorbuscha), coho (O. kisutch), and chinook salmon (O. tshawytscha) also had above-average growth in 1977. A majority of commercially important nonsalmon species that spawned from California to the Bering Sea and have a wide range of life history types also had exceptionally strong year classes from 1976 to 1978. The exceptional survival appears to be related to improved ocean productivity caused by changes in the intensity of the Aleutian Low.