Analysis of catch per unit effort by multivariate analysis and generalised linear models for deep-water crustacean fisheries off Barcelona (NW Mediterranean)

The fishing tactics used to catch the two most valuable decapod species of the Catalan fisheries (Aristeus antennatus and Nephrops norvegicus) were analysed using multivariate statistics. For each fishing tactic, a monthly series of catch per unit effort (CPUE) was obtained. The technical specifications (gross tonnage (GT), engine power (HP) and length (m)) of the vessels participating in the fishery were also investigated. Generalised linear models (GLMs) were employed to analyse the relationship between the independent variables such as year, month, GT, HP and length with the CPUE of each species. The results showed that the models fitted to the A. antennatus data series could explain up to 52.4% of the deviance and that HP and length were important variables in the model, in addition to seasonal and interannual effects. On the other hand, none of the models fitted to the N. norvegicus data series could explain more than 13% of the deviance. These results allow a comparison to be made between the application of GLMs to a fishery with well-defined target species (A. antennatus) and a fishery where the species analysed (N. norvegicus) is only a valuable by-catch. (C) 2003 Elsevier B.V. All rights reserved.