A review of the species composition, distribution and abundance of sharks in both the Spanish commercial
catches (1991-98) and research surveys (1988-98) are carried out. Shark species are by-catches of Greenland halibut
fishery. The proportion of shark species in the total catch is small and the main retained species is the black dogfish,
whereas the main discard is the boreal shark. Since 1996 the retained proportion of black dogfish increase notably,
as well as the proportion of total sharks. In the surveys this shark is the species with the highest biomass index.
Black dogfish is found in the deepest waters. The length range of black dogfish is mainly between 50 and 80 cm,
with a mode about 62-63 cm. No evident geographic pattern in the length distribution is observed during the studied
period
