Reserve management strategy for the sand smelt from brackish lagoons in southern France

Abstract

Visceral fat content, liver weight and carcass weight changes in female sand smelt Atherina boyeri from three brackish lagoons of southern France were studied throughout the year 1993. Each of these three parameters showed a peak in autumn, the visceral fat content peak occurring earlier in the season. Moreover, when ovary weight was maximal, maturing and ripe fish exhibited a second liver weight peak in April, at the beginning of the reproductive season which extended from late February to late August. Reserves were stored in flesh, liver and the abdominal cavity after the end of reproduction and were utilized from late autumn to early summer to overwinter and reproduce. At the onset of the breeding season, visceral fat content and eviscerated weight in larger fish, which started reproducing earlier and stopped later than smaller ones, were relatively higher. From April onwards, as reproductive effort was at its highest, liver and ovary weights decreased. However, eviscerated weight in smaller fish and visceral fat content in larger ones rose slightly before they ceased breeding. It is suggested that the strategy, especially in younger fish, is to avoid complete exhaustion in reproduction. This reduces the risk of subsequent overwintering mortality and increases the chance of reproduction in the future.