Trends in catch-per-unit-effort, stock biomass and recruitment in the North and Northwest Iberian Atlantic Nephrops stocks

Abstract

Nephrops norvegicus is a burrowing decapod with patchy distribution. In the North and Northwest Iberian shelf and upper slope, it is a by-catch species of the bottom trawl mixed fisheries. The International Council for the Exploration of the Sea (ICES) assesses four Nephrops stocks in the area: North Portugal, West and North Galicia and Cantabrian Sea. From a relatively buoyant Nephrops fishery in the period 1975–1989, with annual average landings of 1225 t for the entire area, the landings declined substantially to 270 t in 2000. The general trend for the region is a decline of more than 60% in the catch-per-unit-effort in the last decade. These indicators make the status of the Nephrops stocks a matter of concern. In this paper, trends in the time series of Nephrops fishery data are described and evidence from age-based assessment is given of sharp declines in stock biomass and recruitment