Alex De Robertis

Weight-Length Relationships in Fisheries Studies: The Standard Allometric Model Should Be Applied with Caution

Abstract The standard allometric weight-length relationship W = aLb is widely used in fisheries science to estimate the weight of fish of known length and to compute body condition indices. This relationship is used in abundance surveys such as acoustic surveys to convert abundance at length into estimates of population biomass. Although fitting this relationship to weight-length data over a broad range of body sizes is common practice, the fit of this relationship often does not receive careful scrutiny. We explored the fit of the allometric model as well as alternative weight-length relationships to data from acoustic surveys of walleye pollock Theragra chalcogramma from the North Pacific and found a subtle but persistent lack of fit for the allometric relationship, particularly for the largest and smallest fish in the population. This lack of fit results in biased estimates of population biomass. Analysis of weight-length measurements of 10 additional species indicates that these biases are not restric...

INTERVESSEL COMPARISON OF WALLEYE POLLOCK ACOUSTIC BACKSCATTER RECORDED BY A NOISE-REDUCED AND A CONVENTIONAL RESEARCH VESSEL

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