Fish catch composition of the deep-sea decapod crustacean fisheries in theBalearic Islands (western Mediterranean)

The catch composition of two commercial vessels of the trawl fleet operatin g from Mallorca (Balearic Islands, western Mediterranean) was analysed. A t otal of 4959 kg resulting from 144 fishing hours was sampled from October 1 996 to December 1997. The fishes represented the major proportion with resp ect to the total catch. The analysis of the fish discards assembled them in three depth related groups: group A (mean depth 300 m); group B (mean dept h 489 m); and group C (mean depth 616 m). Species richness, number of indiv iduals and biomass decreased with depth. The diversity and evenness indices also varied with depth, but no significant differences were found. Fishes, with around 70%, dominated the biomass discarded in the three depth groups . Within the landings, fish biomass also represented the major proportion i n groups A and B, but in group C the crustaceans biomass dominated. Our res ults confirm that an important fraction of the catch of the two deep-sea de capod crustacean fisheries is discarded, (C) 2000 Elsevier Science B.V. All rights reserved.