Spanish driftnet fishing and incidental catches in the western Mediterranean

The Spanish driftnet fishery operating since 1994 on the Mediterranean side of the Gibraltar Straits was an illegal activity whose main target was the swordfish Xiphias gladius but which also caught other species incidentally, particularly sunfish Mola mola. Observations during the 1993 and 1994 seasons showed that the fleet was composed of 27 boats deploying nets 3-4 km long. Swordfish constituted 7% of the catch in 1992, 5% in 1993 and 7% in 1994. Sunfish represented 71% of the catch in 1992, 93% in 1993 and 90% in 1994. Sea turtles, mainly loggerhead turtles Caretta caretta, constituted 0.32% of the total catch in 1993 and 0.92% in 1994. The incidental capture of small cetaceans, composed entirely of common dolphins Delphinus delphis in 1992 and of striped dolphin Stenella coeruleoalba and common dolphins in roughtly equal proportions in 1993 and 1994, constituted 0.9% of the catch in 1992, 0.6% in 1993 and 1% in 1994. The bycatch rate of dolphins was 0.1 individuals per km of net set. The total catch of dolphins can therefore be estimated at 366 (95% confidence interval 268-464) animals for the 1993 fishing season and 289 (CI 238-340) for that of 1994. If these figures are added to the undetermined catches of dolphins by the Italian and Moroccan driftnet fleets also operating in the region, it is possible that these catches are not sustainable. (C) 1999 Elsevier Science Ltd. All rights reserved.