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Chinook salmon Oncorhynchus tshawytscha recruitment in the Yukon and Kuskokwim (Y-K) region of western Alaska is important for subsistence and commercial harvest. Recruitment of Chinook salmon in this region has been unpredictable in recent years, and managers and subsistence harvesters are searching for answers. Chinook salmon require freshwater growth to smolt, and larger smolts are thought to have higher marine survival. In this study, I tested for correlations between freshwater growth and recruitment using measurements from scale digitizations. All analyses were conducted at the tributary scale, with one tributary representing each river system. Linear regressions were used to check for correlations between...
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Gillnet catch data from the lower Yukon River, AK, collected from 1990 to 2003 in conjunction with a sonar study to estimate the abundance of migrating fish, were assembled. The full dataset contained 92,029 records with complete species and length information. A subset of data for the eight most prevalent groups of fish was selected for the estimation of net selectivity. The reduced dataset contained 89,984 records for Chinook salmon (Oncorhynchus tshawytscha), summer and fall runs of chum salmon (O. keta), coho salmon (O. kisutch), pink salmon (O. gorbuscha), humpback whitefish (Coregonus pidschian), broad whitefish (C. nasus), and various cisco (Coregonus) species. A Pearson function was used as a net selectivity...
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Harvests of Yukon Chinook salmon increased in the mid-1970s, then declined during 1998 to 2007 in response to fewer returning salmon. We examined annual growth of age-1.3 and age-1.4 Yukon Chinook salmon scales, 1965-2004, and tested the hypothesis that shifts in Chinook salmon abundance were related to annual growth at sea. Annual scale growth trends were not significantly correlated with salmon abundance indices, sea surface temperature, or climate indices, although growth during the first year at sea appeared to have been affected by the 1977 and 1989 ocean regime shifts. Chinook salmon scale growth was dependent on growth during the previous year, a factor that may have confounded detection of relationships...
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Data from high seas tagging experiments (external tags, coded-wire tags, electronic data storage tags) provide the only direct information on the distribution, biology, and ecology of immature and maturing Arctic-Yukon-Kuskokwim (AYK) salmon (Oncorhynchus spp.) migrating in the North Pacific Ocean and Bering Sea. Variation in the spatial and temporal distribution of tagging effort largely reflects changes in international salmon treaty research priorities over the past 52 years (1954-2006). Results of tagging studies indicate that in spring maturing AYK pink O. gorbuscha and coho O. kisutch salmon and immature and maturing AYK sockeye O. nerka and chum O. keta salmon are distributed primarily in the northeastern...
Since 1996, U.S. Fish and Wildlife Service biologists have annually used fish wheels to capture migrating adult fall chum salmon Oncorhynchus keta in the main-stem Yukon River, Alaska, and estimated their abundance via mark- recapture methods. In each year of the study, the mark rate of captured fish at a site near Rampart has been substantially greater than rates observed at numerous locations upriver of that site. The factors most likely to cause the observed reduction in the mark rate are violations of mark-recapture model assumptions or the mortality of marked fish between the Rampart site and upriver locations. Results of studies conducted through 2000 were most consistent with the hypothesis of mortality....
Many fisheries for Pacific salmon Oncorhynchus spp. are actively managed to meet escapement goal objectives. In fisheries where the demand for surplus production is high, an extensive assessment program is needed to achieve the opposing objectives of allowing adequate escapement and fully exploiting the available surplus. Knowledge of abundance is a critical element of such assessment programs. Abundance estimation using mark—recapture experiments in combination with telemetry has become common in recent years, particularly within Alaskan river systems. Fish are typically captured and marked in the lower river while migrating in aggregations of individuals from multiple populations. Recapture data are obtained using...
Chum salmon (Oncorhynchus keta ) are important for subsistence and commercial harvest in Alaska. Variability of returns to western Alaskan drainages that caused economic hardship for stakeholders has led to speculation about reasons, which may include both anthropogenic and environmental causes in the marine environment. Mixed stock analysis (MSA) compares genetic information from an individual caught at sea to a reference baseline of genotypes to assign it to its population of origin. Application of genetic baselines requires several complex steps that can introduce bias. The bias may reduce the accuracy of MSA and result in overly-optimistic evaluations of baselines. Moreover, some applications that minimize bias...
Gillnet catch data from the lower Yukon River, AK, collected from 1990 to 2003 in conjunction with a sonar study to estimate the abundance of migrating fish, were assembled. The full dataset contained 92,029 records with complete species and length information. A subset of data for the eight most prevalent groups of fish was selected for the estimation of net selectivity. The reduced dataset contained 89,984 records for Chinook salmon (Oncorhynchus tshawytscha), summer and fall runs of chum salmon (O. keta), coho salmon (O. kisutch), pink salmon (O. gorbuscha), humpback whitefish (Coregonus pidschian), broad whitefish (C. nasus), and various cisco (Coregonus) species. A Pearson function was used as a net selectivity...
Chum salmon (Oncorhynchus keta) are the most abundant species of salmon spawning in the Yukon River drainage system, and they support important personal use, subsistence, and commercial fisheries. Chum salmon returning to the Tanana River in Interior Alaska are a significant contribution to the overall abundance of Yukon River chum salmon and an improved understanding of habitat use is needed to improve conservation of this important resource. We characterized spawning habitat of chum salmon using the mainstem Tanana River as part of a larger study to document spawning distributions and habitat use in this river. Areas of spawning activity were located using radiotelemetry and aerial helicopter surveys. At 11 spawning...
Concerns regarding the size and sex composition of Yukon River Chinook salmon Oncorhynchus tshawytscha have been expressed in public meetings for over a decade. However, reports of small size and low numbers of females have become increasingly common in recent years, and apprehension over the long-term health of the stock has grown within the drainage. In response to these reports, the Salmon Size Subcommittee of the US/Canada Yukon River Joint Technical Committee was formed and charged with advising the Committee, and thereby the US/Canada Yukon River Panel, with respect to changes in Chinook salmon age, sex, and size composition. This report, which summarizes the findings of prior investigations and the scientific...
map background search result map search result map Comparative landscape genetic analysis of three Pacific salmon species from subarctic North America Abundance and Run Timing of Adult Salmon in the Kateel River, Koyukuk National Wildlife Refuge, Alaska, 2001-2003 High Seas Distribution, Biology, and Ecology of Arctic-Yukon-Kuskokwim Salmon: Direct Information from High Seas Tagging Experiments, 1954-2006 Pacific Region integrated fisheries management plan, chinook and fall chum salmon, April 1, 2009 to March 31, 2010, Yukon River, Y.T Climate, growth and population dynamics of Yukon River Chinook salmon A versatile net selectivity model, with application to Pacific salmon and freshwater species of the Yukon River, Alaska Mixed-Stock Analysis of Yukon River Chum Salmon: Application and Validation in a Complex Fishery Evidence of handling mortality in fall chum salmon caused by fish wheel capture on the Yukon River, Alaska Freshwater growth and recruitment of Yukon and Kuskokwim River Chinook salmon: A retrospective growth analysis Abundance and Run Timing of Adult Salmon in the Kateel River, Koyukuk National Wildlife Refuge, Alaska, 2001-2003 Pacific Region integrated fisheries management plan, chinook and fall chum salmon, April 1, 2009 to March 31, 2010, Yukon River, Y.T Evidence of handling mortality in fall chum salmon caused by fish wheel capture on the Yukon River, Alaska Comparative landscape genetic analysis of three Pacific salmon species from subarctic North America A versatile net selectivity model, with application to Pacific salmon and freshwater species of the Yukon River, Alaska Mixed-Stock Analysis of Yukon River Chum Salmon: Application and Validation in a Complex Fishery Freshwater growth and recruitment of Yukon and Kuskokwim River Chinook salmon: A retrospective growth analysis Climate, growth and population dynamics of Yukon River Chinook salmon High Seas Distribution, Biology, and Ecology of Arctic-Yukon-Kuskokwim Salmon: Direct Information from High Seas Tagging Experiments, 1954-2006