17 INSTARS OF ADULT LIFE IN FEMALE ARISTEUS-ANTENNATUS (CRUSTACEA, DECAPODA, ARISTEIDAE) - A NEW INTERPRETATION OF LIFE-SPAN AND GROWTH

A new interpretation of growth in A. antennatus is proposed on the bas is of data recorded over a period of twenty years on the fishing groun ds off Portofino. Detailed size-frequency distributions of female A. a ntennatus, obtained from on board measurements of large numbers per ha ul or per day of fishing, have been interpreted as formed of about 17 growth instars. Five of these, in the range 38-53 mm CL, were traced i n their growth after the apparently fortuitous event of a massive recr uitment which took place in 1987. The shift indicated above of five in stars occurred in 3 years; a long life span, of about 8-9 years, was t hen assigned to the female red shrimp. Males were supposed to have an identical life span, with smaller sizes at age. The '1987 shrimps' wer e and remained for years distinct from the previous ones, in terms of both their size structure and reproductive characteristics. They were similar to southern Mediterranean stock(s) and slowly evolved towards a northern pattern. This fact points to a substantial affinity among A . antennatus populations in different Mediterranean areas.