Movements of Yearling Chinook Salmon during the First Summer in Marine Waters of Hood Canal, Washington

Abstract

Abstract Migration is a fundamental component of the life history and ecology of many species, but the extent and duration of specific migrations can vary depending on species and environment. Chinook salmon Oncorhynchus tshawytscha are characterized by a spectrum of life history types with different migration patterns and spatial distributions. The objective of this study was to quantify the movements of yearling Chinook salmon smolts during their initial summer in Hood Canal, a long, narrow fjord in western Puget Sound, Washington. Fifty‐eight yearling hatchery‐reared smolts were tagged with acoustic transmitters and tracked during May–August 2008 with a network of 50 receivers placed throughout Hood Canal. A total of 41 fish were detected during the study period; of these, 18 fish were still being detected in Hood Canal after 100 d. Fish initially congregated near the release site and gradually dispersed during summer; individual movement rates ranged between 0.44 and 1.52 body lengths/s. Fish movement occurred both with and against tidal currents, and nearly all fish showed some period of inactivity, especially as recorded on receivers near estuaries and tidal deltas. Eight fish (20%) were detected as leaving Hood Canal during the study, but seven of them later returned to Hood Canal. The extended use of Hood Canal as rearing habitat indicated the importance of such environments beyond their role as migratory corridors to the Pacific Ocean.