Stock assessment of humpback whitefish and least cisco in the Chatanika River during 1992

Description

Stock assessment of humpback whitefish Coregonus pidschian and least cisco Coregonus sardinella occurred in a 105 kilometer area of the Chatanika River, near Fairbanks, Alaska during August 1992. Mark-recapture experiments were conducted simultaneously for both species as two electrofishing crews systematically sampled the river during two complete passes, with two pulsed DC electrofishing boats. The investigation was timed to correspond to the upstream spawning migration of both species, and to provide in-season estimates of abundance prior to the onset of a recreational spear fishery. An estimated 20,180 (SE = 1,663) humpback whitefish (^360 millimeters fork length) were present in the study area. The stock was characterized by a high proportion of large humpback whitefish (420 millimeters fork length) with ages 7, 8, and 9 predominating. The continued absence of young humpback whitefish indicates potential recruitment failures to the spawning stock over the next few years. An estimated 86,989 (SE = 9,097) least cisco (290 millimeters fork length) were present in the study area. The stock was distributed almost evenly between all lengths, which ranged from 290 to 427 millimeters fork length, with ages 3, 4, and 6 most abundant. Almost 36% of the assessed stock was age three and although they are not fully recruited, indicates potentially strong recruitment in 1993.

Subjects

Series Statement

• Fishery data series -- no. 93-25.

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