Definition of fleet components in the Portuguese bottom trawl fishery

The bottom trawl fishery in Portuguese continental waters is a multi-species fishery where a large number of commercial species are landed by a fleet composed of about 100 trawlers. This paper presents the results obtained from applying ordination and classification methods to the 2002-2004 monthly landings per vessel with the purpose of defining landing profiles (LPs) and associated fleet components (FCs). Six different LPs emerged from the analysis, each defined by the relative importance of target and by-catch species. A correspondence between these LPs and groups of trawlers was established, suggesting the existence of three main fleet components, or groups of trawlers involved in the same fishing pattern over time. The crustacean fleet, targeting the deep-water crustaceans, Norway lobster, Nephrops norvegicus, rose shrimp, Parapenaeus longirostris, and red shrimp, Aristeus antennatus, and comprising two different LPs, is composed of the most recent and technologically advanced vessels. The 'fish' fleet, mainly targeting semi-pelagic species such as the horse mackerel Trachurus trachurus, the Atlantic mackerel, Scomber scombrus, and the Chub mackerel, Scomber japonicus, constitutes a diversified group in terms of their technical characteristics and LPs. A small number of trawlers have the Octopodidae, the cuttlefish, Sepia officinalis and benthic fish species as their most important landings, constituting a well individualized, and previously unsuspected, fleet component. (c) 2006 Elsevier B.V. All rights reserved.