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Division: Sport Fish
Title: Assessment of coho salmon from the Kenai River, Alaska, 2000
Author: Massengill, R. and J. A. Carlon
Year: 2004
Report ID: Alaska Department of Fish and Game, Fishery Data Series No. 04-23, Anchorage.
Abstract: Since 1991, the Alaska Department of Fish and Game has assessed coho salmon Oncorhynchus kisutch of the Kenai River with an annual research program designed to estimate both the commercial harvest from Upper Cook Inlet and the Kenai River drainage-wide smolt production. As part of this ongoing study, coho salmon smolt were captured and marked with coded wire tags and adipose finclips at a weir on the Moose River, a tributary to the Kenai River. In 1999, 114,885 coho sa1mon were marked with adipose finclips, an estimated 113,824 were released alive with tags, and 163,484 were enumerated emigrating from the Moose River. In 2000, coho salmon smolt tagged in 1999 at the Moose River returned to the Kenai River as adults. Fish wheels and drift gillnets on the Kenai River, and a weir at the Russian River (tributary to the Kenai River), were used to capture returning adult coho salmon to estimate the proportion bearing coded wire tags, which in turn was used to estimate commercial harvest of Kenai River origin. Captured coho from these efforts were examined for the presence of an adipose finclip. Additionally, a tag detector wand was used to confirm tag presence in adipose finclipped coho at the fish wheels. Although the marked proportion varied significantly (P<0.006) over weekly periods in all inriver capture efforts, the pooled fish wheel catch appeared most representative for use in estimating the commercial harvest of coho of Kenai River origin. The marked coho proportion from drift gillnets and the weir had either higher temporal or spatial bias. The 1999 drainage-wide smolt abundance was an estimated 578,335 coho salmon (SE = 19,884), based on the pooled number of fish examined at the fish wheel (3,413), the number observed to be missing an adipose fin (672), and the number of smolt marked and released with an adipose finclip in 1999 (114,885). Based on the recovery of harvested adults marked with coded wire tags and adipose finclips in selected Upper Cook Inlet commercial fisheries, an estimated 531 (SE = 122) coho salmon of Kenai River origin were harvested in the Central District drift gillnet fishery, an estimated 2,351 (SE = 223) were harvested in the Central District eastside set gillnet fishery, and 83 (SE = 21) by all Northern District set gillnet fisheries for a total of 2,965 (SE = 255). Sampling within other areas of Upper Cook Inlet indicated that commercial harvest of Kenai River coho was very low. The estimated harvests represented 22% of the eastside set gillnet fishery and 0.4% of the total drift gillnet fishery.
Keywords: coho salmon, Oncorhynchus kisutch, population assessment, sustained yield, contribution, commercial harvest, coded wire tag, Kenai River, smolt abundance, wild.