REPRODUCTIVE-BIOLOGY AND ECOLOGY OF A DEEP-DEMERSAL FISH, ALFONSINO BERYX SPLENDENS, OVER THE SEAMOUNTS OFF NEW-CALEDONIA

The reproductive biology of the alfonsino Beryx splendens was studied by histological examinations, gonadosomatic index and macroscopic scal es of maturation of a large sample of gonads. Alfonsino is a gonochori c species. The size-frequency distribution of the sex ratio was bimoda l and considered to be due to size dimorphism. In New Caledonia, the b reeding period of this species occurs during the southern summer, with a peak in December to January. The spawning stage is attained at a mi nimum fork length of 28 cm for females and 33 cm for males. The size a t which 50% of the population attain sexual maturity (FL50) is 33.2 cm for females and 34.5 cm for males. Maximum potential fecundity is est imated to lie between 270 000 to 675 000 eggs for fish between 34 and 40 cm in fork length. It was possible to differentiate vegetative zone s, in which juvenile alfonsino grow until they reach maturity, from re productive zones (fishing grounds) which are inhabited by mature indiv iduals. The larvae and juveniles could be carried from the reproductiv e zone to the vegetative zone by currents in an oceanic eddy system.