Distribution and Biology of the Blackmouth Catshark<i>Galeus melastomus</i>in the Alboran Sea (Southwestern Mediterranean)

Abstract

The distribution, population size structure and reproductive biology of blackmouth catshark Galeus melastomus in the Alboran Sea were studied from 438 bottom trawls performed at depths of 40 to 796 m during twelve surveys carried out between 1994 and 2002. The species was only captured at the two deepest strata (below 200 m), reaching its maximum abundance and biomass between 501 and 800 m. Maximum indices, obtained in 1997 and 2002, indicate no specific trend in abundance, whereas the biomass showed a slightly decreasing trend from 1994. Similarly, seasonal variation of abundance and biomass during the last two years showed maximum values of biomass in autumn but with no trend in abundance. The size of the specimens ranged from 10 to 63 cm and all size groups were well represented in the length frequencies during all seasons. Juveniles and adults were restricted to depths below 500 m, while recruits were distributed throughout the whole bathymetric range in which the species was found. Both recruitment and spawning were continuous throughout the year and the total length at first maturity was calculated as 44.3 and 48.8 cm for males and females, respectively. Finally, the great abundance and biomass of the species as well as its wide population structure are compared and discussed with other Mediterranean areas.