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Division: Sport Fish
Title: Ninilchik River Chinook salmon assessment, 1999 and 2000
Author: Begich R. N.
Year: 2006
Report ID: Alaska Department of Fish and Game, Fishery Data Series No. 06-27, Anchorage
Abstract: During 1999 and 2000 naturally- (naturally-produced) and hatchery-produced Chinook salmon Oncorhynchus tshawytscha returns to the Ninilchik River were assessed with a weir to determine the age and sex compositions of total escapements and to estimate the contribution of Chinook salmon that stray to the Ninilchik River from three Kachemak Bay Chinook salmon enhancement locations. Additionally during 2000, a random sample of sport harvested Chinook salmon were examined for an adipose finclip to estimate the stock composition of the harvest sampled each weekend in the Ninilchik River below the Sterling Highway. The escapement of naturally-produced Chinook salmon was 1,576 fish in 1999 and 1,553 fish in 2000. The estimated 2-year average naturally-produced stock contribution to the escapement was 71%. Hatchery-produced escapements were 573 fish and 685 fish during 1999 and 2000, respectively. The average contribution of hatchery fish to the escapements was 29%. Stock composition of the immigrations varied significantly over the duration of the returns to the weir. Median date of weir immigration for naturally-produced fish was July 13, 1999 and July 14, 2000, while the median date of weir immigration for hatchery fish was July 24 for both years. Two hundred thirty-one coded wire tags were decoded from 237 Chinook salmon that were sacrificed at the weir. No strays from Kachemak Bay Chinook salmon enhancement locations were detected, 230 originated from Ninilchik River hatchery releases, and one originated from the Alaska Department of Fish and Game (ADF&G), Crooked Creek enhancement program, a tributary of the Kasilof River. The contribution of hatchery-produced Chinook salmon to the sport harvest sampled in the lower river was 49% (SE = 4%) and was similar among weekend fishing periods. Continuing the Chinook salmon assessment at Ninilchik River weir is recommended to fully understand run-timing characteristics of and contribution to sport harvest of hatchery returns so that annual stock surpluses of hatchery-produced Chinook salmon can be more fully utilized.
Keywords: Chinook salmon, Oncorhynchus tshawytscha, Ninilchik River, naturally-produced, hatchery, return, escapement, weir, contribution, adipose finclip, and coded wire tag.