Distribution, abundance and growth of juvenile salmonids off the coast of Oregon and Washington, summer (1980)

Abstract

Juvenile salmonids (< 50 cm) were sampled by purse seine off the Pacific coast from Tillamook Bay, Oregon, to Copalis Head, Washington, during the period May through September (1980). Temporal distribution and abundance of the major Columbia River species were determined. Spring chinook salmon ( Oncorhynchus tshatuytscha) and steel head ( Salmo gairdneri) were present only during early cruises and were distributed almost entirely in the Columbia River plume and the sample area to the north. Coho salmon ( O. kisutch) and fall chinook salmon were distributed more uniformly throughout the sampling area and were relatively abundant throughout the sampling period. Concentrations of fish were found only within 28 km of the shore. A number of fish that had been marked before or during their outmigration from the Columbia River system were recaptured. It appeared possible that with concentrated sampling in areas with high fish abundances, sufficient numbers of marked juvenile salmonids could be captured to provide relative survival estimates between different stocks of Columbia River fish.