Some biological parameters of black hakes Merluccius senegalensis and Merluccius polli in Mauritanian waters

The black hakes Merluccius senegalensis Cadenat 1950 and Merluccius polli Cadenat 1950 are demersal species whose geographical distribution overlaps off Mauritanian waters. Spanish trawling and longliner fleets catch both species. During 2003 and 2004, 8101 and 2691 specimens of M. polli and M . senegalensis respectively were sampled biologically in several scientific watching campaigns onboard of commercial trawling ships and two longline experimental campaigns. From the information stored, it has been calculated the total length (cm) vs. total weight (g) and total length vs. total gutted weight relationships by sexes and species, as well as the conversion factor from gutted to total weight. By means of macrocospic analysis of the gonadic stages and the evolution of the gonadosomatic indexes (GSI) of both species it has been located the spawning season and zones. The spawning season extends mainly from November to February with a peak in December-January for both species, but with quite early in M. senegalensis . The males reaches the sexual maturity at lower lengths than females in both hake species ( 34, 3 - 39,2 cm in M. polli and 33,0 -39,2cm ;in M. senegalensis ) and females of both species reaches at the same length the first maturity. For the combined sexes, M. senegalensis reach the firsts maturity at slightly lower length (35,4 cm) than M. polli (37,0 cm). Females dominate the sex ratio in the populations of both species. The largest specimen caught (79,6 cm) corresponded to a female of M. senegalensis ,aswellastwomalesof great size for the same specie of (65,7 and 67,5 cm total length)