Type of Presentation

Oral

Session Title

General species and food webs

Location

2016SSEC

Description

Alternative forms of migratory behavior can have substantial consequences for the growth, survival, and fitness of the individuals involved. Salmonids vary in the tendency of individuals to migrate to marine waters (anadromy) or remain in freshwater habitats. In addition, substantial variation in migratory patterns can exist among anadromous and resident species. This talk summarizes our use of hydroacoustic telemetry to investigate the movement patterns of anadromous Chinook salmon Oncorhynchus tshawytscha remaining in the marine waters of Puget Sound after ocean entry rather than continuing out to the coastal waters of the North Pacific Ocean, as is typical of the species. We then compared the movement patterns of Chinook salmon with those of a closely related species, coho salmon O. kisutch. Most (37 of 53 = 70%) Chinook salmon remained in Puget Sound (“residents”) and few of those left the region within Puget Sound where they were first captured, despite ready access to suitable habitat elsewhere. However, 30% of the individuals, termed transients, subsequently left Puget Sound and moved to the coastal Pacific Ocean. Residents and transients did not differ in initial body size, date or place of tagging, or rearing history (hatchery or wild). Combined with other sources of information, these data support the conclusion that Chinook and coho salmon display alternative forms of migratory behavior (resident and transient) that are best described as modes along a continuum rather than discrete categories. However, in both species the residents showed very limited movement within Puget Sound; this behavior affects their exposure to agents of natural mortality, fisheries, and other physiological processes such as the uptake of chemical contaminants.

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

2016SSEC

Alternative forms of migratory behavior can have substantial consequences for the growth, survival, and fitness of the individuals involved. Salmonids vary in the tendency of individuals to migrate to marine waters (anadromy) or remain in freshwater habitats. In addition, substantial variation in migratory patterns can exist among anadromous and resident species. This talk summarizes our use of hydroacoustic telemetry to investigate the movement patterns of anadromous Chinook salmon Oncorhynchus tshawytscha remaining in the marine waters of Puget Sound after ocean entry rather than continuing out to the coastal waters of the North Pacific Ocean, as is typical of the species. We then compared the movement patterns of Chinook salmon with those of a closely related species, coho salmon O. kisutch. Most (37 of 53 = 70%) Chinook salmon remained in Puget Sound (“residents”) and few of those left the region within Puget Sound where they were first captured, despite ready access to suitable habitat elsewhere. However, 30% of the individuals, termed transients, subsequently left Puget Sound and moved to the coastal Pacific Ocean. Residents and transients did not differ in initial body size, date or place of tagging, or rearing history (hatchery or wild). Combined with other sources of information, these data support the conclusion that Chinook and coho salmon display alternative forms of migratory behavior (resident and transient) that are best described as modes along a continuum rather than discrete categories. However, in both species the residents showed very limited movement within Puget Sound; this behavior affects their exposure to agents of natural mortality, fisheries, and other physiological processes such as the uptake of chemical contaminants.