Status of rainbow trout stocks in the Agulowak and Agulukpak Rivers of Alaska during 1992
By: by Dan O. Dunaway.
Contributors: Alaska. Division of Sport Fish.
Series: Fishery data series -- no. 93-41.
Publisher: Alaska Dept. of Fish and Game, Division of Sport Fish
Published: 1993
Place of publication: Anchorage, Alaska
Language: eng
Number of pages: 46
Subjects: Rainbow trout -- Alaska -- Agulowak River -- Statistics.; Rainbow trout -- Alaska -- Agulukpak River -- Statistics.; Fishes -- Alaska -- Agulowak River -- Statistics.; Fishes -- Alaska -- Agulukpak River -- Statistics.; Fish populations -- Alaska -- Agulowak River -- Statistics.; Fish populations -- Alaska -- Agulukpak River -- Statistics.
Genres: Statistics.
Description: Mark and recapture methods and the Chapman modified Petersen estimator were used to estimate the abundance of rainbow trout Oncorhynchus mykiss in two rivers near Bristol Bay in southwestern Alaska during 1992. Rainbow trout were captured with hook and line gear from 5 September to 6 October on the Agulowak River and 18 September to 1 October on the Agulukpak River. Over 1,300 fish were captured and 32 tagged fish were recaptured on the Agulowak River to produce an estimate of 13,689 (Standard error = 2,231) rainbow trout > 250 millimeters in length. On the Agulukpak River, 601 rainbow trout were captured and 36 fish were recaptured; but the estimate of 2,446 (Standard error = 348) fish was restricted to fish > 340 millimeters in length. The numbers of rainbow trout per kilometer of river (1,287-2,489 fish/kilometer) estimated in the Agulukpak and Agulowak rivers were much higher than the 54-274 rainbow trout/kilometer estimated in the Kenai River. Comparisons between age compositions of rainbow trout sampled in the Agulowak River in 1992 and 1988 were significantly different (v2 = 60.19, df = 5, P = 0.00) with the 1992 sample containing larger proportions of older aged fish. The change in the age distribution of rainbow trout in the Agulowak River was attributed to harvest and gear restrictions enacted in February 1990. A comparison of age compositions of Agulukpak River rainbow trout sampled in 1992 and 1987 found no changes (v2 = 3.43, df = 5, P = 0.64). The condition factor as described by the natural log of weight as a function of the natural log of length showed significant linear relationships for fish in both rivers. Comparisons between the condition factors of hook-marked fish versus nonmarked fish showed no difference in either river. A system to train personnel to make consistent age determinations from rainbow trout scales was developed.
Notes: "October 1993".

"Literature cited": p. 29-31.

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