Movements of sub-adult Chinook salmon, Oncorhynchus tshawytscha, in Puget Sound, Washington, as indicated by ultrasonic tracking

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Kagley, Anna; Smith, Joe; Quinn, Thomas; Fresh, Kurt; Chamberlin, Joshua; Spilsbury-Pucci, Dawn; Moore, Stephanie; Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)
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Terrestrial and Aquatic Ecology
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Salmonids show a wide variety of migration patterns. Such variation is especially prevalent in Chinook salmon, Oncorhynchus tshawytscha. This species migrates to coastal and open ocean waters, and the tendency to use these different marine environments varies markedly among populations. For example, some Chinook salmon that enter Puget Sound do not migrate to the sea as juveniles in their first year but rather remain as “residents” through (at least) the following Spring. Known locally as blackmouth, these fish are the focus of extensive sport fisheries. In this study, we used acoustic telemetry to examine questions surrounding resident Chinook salmon in Puget Sound. The overall objective of this study was to determine the extent to resident and migratory behavior patterns are distinct or ends of a continuum of movement patterns, and then characterize the movements of resident fish. We first assessed the proportion of fish, caught and tagged as immature residents (inferred from the locations and dates of capture), that remained within Puget Sound and the proportion that moved to the coastal region, and tested the hypotheses that origin (wild or hatchery), location and season of tagging, fish size and condition factor would influence the tendency to remain resident. Second, we characterized the movements by resident fish with Puget Sound at a series of different spatial scales: movement among the major basins, travel rates, and areas of concentration within Puget Sound. Third, we tested the model of seasonal north-south movement patterns by examining the distribution of detections over the whole area and year. Because residents represent a significant portion of the Puget Sound Chinook salmon Evolutionarily Significant Unit, currently listed as Threatened under the U. S. Endangered Species Act, better understanding of their movements in Puget Sound will help identify critical habitat use patterns and evaluate fishery management objectives as the species crosses jurisdictional boundaries.