A multispecies approach to subsetting logbook data for purposes of estimating CPUE

An initial step in catch and effort analysis is determination of what subset of the data is relevant to the analysis. We propose an objective approach to subsetting trip records of catch and effort data when fishing locations are unknown; the species composition taken on a fishing trip is used to infer if that trip's fishing effort occurred in a habitat where the species of interest (the target species) is likely to occur. We use a logistic regression of multispecies presence-absence information to predict the probability that the target species would be present. A critical value of probability that best predicts target species presence and absence in the data set forms an objective basis for subsetting the trip records. We test this approach by applying it to a data set where individual fishing locations are known, and we show that the method is an effective substitute for information on individual fishing locations. (C) 2004 Elsevier B.V. All rights reserved.