Influence of environmental factors on commercial trawl catches of Nephrops norvegicus (L.)

Environmental factors that affect small-scale spatio-temporal variability in commercial catch rates of Nephrops norvegicus are analysed. Catch and effort data were obtained from a selection of fishers that operated in the Nephrops fishery on a daily basis, and the environmental factors studied were those considered by the fishers themselves to be the ones driving variability in the fishery. Using multivariate regression analysis and MANOVA, depth, atmospheric pressure, cloud cover, and sea state were found to affect the catch rate of the Nephrops deep-water fishery in the northwestern Mediterranean. The results are consistent with the hypothesis already in the scientific literature that the light intensity reaching the seabed has a primary influence on the activity rates of Nephrops and hence the species' vulnerability to trawling. The value of collaborating with fishers in establishing scientific hypotheses and obtaining data, and specifically drawing on their knowledge of the ecosystem in which they operate, is shown by this study, a case study in integrating Traditional Ecological Knowledge (TEK) into fisheries management. (C) 2001 International Council for the Exploration of the Sea.