Burbot research in rivers of the Tanana River drainage, 1996

Description

As part of an ongoing stock assessment program, burbot were sampled in two river sections (approximately 25 km in length), one each in the Tanana and Chena rivers, representing the area where most harvest occurs. These sections have been sampled annually since 1986 and 1988, respectively. A systematic sampling design was used, whereby hoop traps were set and moved daily over an eight day period. Estimates of mean catch per unit effort, mean length, length distributions, and proportions of catch for three size categories were calculated. Estimates for each were within the range of observed values from previous sampling years. Catch-age analysis was used to combine harvest estimates from the statewide harvest survey and age composition from catch sampling with auxiliary information in the form of angler effort to estimate exploitable abundance of burbot in the Tanana River drainage. The CAGEAN model results showed a decreasing trend in exploitable abundance from 1987 to 1995, which corresponds to a trend in increased fishing mortality during that time. Catch-age analysis appears to be a promising method for estimating trend in abundance for burbot in the Tanana River drainage, but improvements in the catch sampling program, a longer time series of data, and more accurate estimates of fishing effort are needed to improve the model estimates.

Subjects

Series Statement

• Fishery data series -- no.97-34.

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