FY 1995

The El Niño of 1983 as reflected in the ichthyoplankton off Washington, Oregon, and northern California

Doyle, M.J.

Can. Spec. Publ. Fish. Aquat. Sci., 121, 161–180, In Climate Change and Northern Fish Populations, R.J. Beamish (ed.) (1995)

Anomalies observed in the ichthyoplankton off the U.S. northwestern coast during 1983 included temporal shifts in peak abundance of eggs and larvae among certain species, reduced abundance of eggs and larvae among other species, the occurrence of rare southern species, and changes in distribution patterns. These anomalies are attributed to changes in spawning patterns and advection of eggs and larvae in response to the physical oceanographic anomalies characterizing the 1983 El Niño event in this region. Such changes, which resulted from the physical forcing on the ecosystem, seem to have been mediated mainly through water temperature and transport anomalies. A high level of stability in the spawning and early life history patterns of fish species in this region is implied by the fact that only a small portion of the dominant species seem to have been affected by the strong El Niño event of 1983. As well, in 1984 and 1985, abundance and distribution patterns in the ichthyoplankton had returned to the apparently normal patterns observed in 1980, 1981, and 1982.