Differences in the condition of Norway lobsters (Nephrops norvegicus (L.)) from trawled and creeled fishing areas

Abstract

The condition of trawled and creeled Norway lobsters, Nephrops norvegicus, was compared in individuals caught along the Swedish west coast. Female and male N. norvegicus were collected from trawled and creeled areas in the spring and autumn. Their nutritional state was determined by analysing individuals for haemocyanin concentration, the dry weight/wet weight relationship in muscle and hepatopancreas and the percentage dry weight of muscle and hepatopancreas of total animal dry weight. All parameters were measured on an individual basis and checked for size dependence. Creeled individuals were generally found to be in better condition than individuals from trawled areas, and animal condition increased from spring to autumn. Autumn males from creeled sites were overall in the best condition, having the highest mean haemocyanin concentration, muscle and hepatopancreas dry weight/wet weight relationship and percentage dry weight of muscle tissue. Claw symmetry (paired cutters) was suggested as an indicator of limb loss, with the highest occurrence found in females from trawled sites. Crusher absence had no effect on the animal's individual percentage dry weight of muscle, although the mean was lower in trawled females than in other groups. Resource limitation and physical stress are discussed as possible underlying factors affecting the observed differences.

Keywords:

• Condition
• fishing gear
• growth
• Nephrops norvegicus
• regeneration

Acknowledgments

Constructive comments on the manuscript were given by Professor S. P. Baden and two anonymous referees. Financial support was given by a Swedish Environmental Protection Agency grant (12404 b) and a Swedish Research Council grant (621-2001-3670).