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Mark-recapture studies of adult Taku River sockeye salmon (Oncorhyncus nerka) stocks were conducted by the Alaska Department of Fish and Game and the Taku River Tlingit First Nation in 2003. The objectives of the studies were to provide inseason estimates of the inriver abundance of sockeye O. nerka and to document biological charactieristics (migratory timing, migratory raes and age, sex, and size composition) of Taku River sockeye stocks. Tagged-to-untaggedratios of salmon harvested in the Canadian inriver gillnet fisheries were used to develop the estimates of the inriver abundance of sockeye. A total of 5,969 sockeye salmon were captured in fish wheels located in Canyon Island, Alaska, of which 5,463, were tagged and 1,744 (31.9%) were subsequently recovered in fisheries or on the spawning grouds. The inriver run of sockeye salmon past Canyon Island from June 5 to September 17 was estimated to be 200,918 fish (95% confidence interval 180,905 to 220,931). Canadian commercial, aboriginal and test fisheries harvested 32,933, 267 and 27 sockeye, respectively, resulting in a spawning escapement estimate estimate of 167,691 sockeye salmon. Based on mean date and standard deviation of migration timing the sockeye salmon run was approximately one day earlier and more compressed than the 1984-2002 average. The Kuthai Lake sockeye salmon stocks dominated the early portion of the run, the Little Trapper Lake the middle portion, and the Tatsamenie Lake and mainstem stocks the late portion. The fish wheel catches of 15,604 pink salmon, 262 chum salmon, and 49steelhead salmon were 2.8%, 50.8% below average and 29,7% above average, respectively. The pinksalmon run was five days earlier and slightly more compressed than average.
A cooperative study involving the Department of Fisheries and Oceans Canada, the Alaska Department of Fish and Game, and the Taku River Tlingit First Nation was conducted to estimate the number of spawning Chinook salmon Oncorhynchus tshawytscha in the Taku River in 2003 with a mark-recapture experiment. Fish were captured at Canyon Island on the lower Taku River with fish wheels from May through August and were individually marked with back-sewn, solid-core spaghetti tags. All tagged fish were also batch marked with an opercle punch plus removal of the left axillary appendage. Sampling on the spawning grounds in tributaries was used to estimate the fraction of the population that had been marked. The estimated spawning abundance of small Chinook salmon ( 400 mm long; mid-eye to fork of tail) was 3,489 (SE = 1,052). Spawning abundance of medium-size Chinook salmon (401-659 mm) was estimated to be 16,780 (SE = 2,274). Finally, spawning abundance of large-size fish (= 660 mm) was estimated to be 36,435 (SE = 6,705), and the estimated total of all fish was 56,704 (SE = 7,158). The sum of the peak aerial survey counts of large spawning Chinook salmon conducted at five index tributaries of the Taku River was 16% of the mark-recapture estimate. Age 1.3 fish (1998 brood year) constituted an estimated 40% of the spawning population, followed by age 1.2 fish (1999 brood year), which constituted an estimated 29% of the population