Distribution and movements of Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin

• Main Author: Eiler, John H.
• Other Authors: Schreck, Carl B., Peterson, James T., Heppell, Selina S., Luh, Hans, Fisheries and Wildlife, Oregon State University. Graduate School
• Format: Doctoral or Postdoctoral Thesis
• Language: English; unknown
• Published: Oregon State University
• Subjects: Chinook salmon > Migration > Yukon River Watershed (Yukon and Alaska); Chinook salmon > Yukon River Watershed (Yukon and Alaska) > Geographical distribution; Chinook salmon > Spawning > Yukon River Watershed (Yukon and Alaska); Yukon river; Alaska; Yukon
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/zp38wf93x

Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin and other large river systems in western Alaska have declined dramatically since the late 1990s. This continuing trend has raised concerns over the future status of the returns, and severely impacted commercial and subsistence fisheries within the drainage. Management is further complicated by the mixed-stock composition of the run, the presence of other temporally similar salmon species, and the need to equitably allocate harvests between the numerous fisheries and user groups scattered throughout the basin. Detailed information is needed on Chinook salmon run characteristics to better understand and manage the returns, and facilitate conservation efforts. However, this goal is exacerbated by the massive size and remote nature of the basin, the large number of highly mobile fish, and the compressed timing of the run. To address these challenges, radio telemetry was used to determine the stock composition and spawning distribution of the returns, and the migratory characteristics of the fish. The migratory patterns exhibited by returning salmon provide a number of insights into the status of the run. Since the Yukon River is essentially free-flowing (i.e., not regulated), this study also presented an opportunity to document the distribution and upriver movements of large returns of wild Chinook salmon under natural conditions. During 2002-2004, returning adult Chinook salmon were captured in the lower Yukon River (approximately 300 km upriver from the river mouth), tagged with radio transmitters, and tracked upriver using remote tracking stations located on important migratory routes and major spawning tributaries. Aerial tracking surveys were used to locate fish in spawning areas and between stations. The fish responded well to the capture and handling procedures, with most (2,790, 98%) resuming upriver movements. Although the fish initially displayed a negative tagging response, with slower migration rates observed immediately after ...