FEMALE REPRODUCTIVE-BIOLOGY OF THE SAND SMELT IN BRACKISH LAGOONS OF SOUTHERN FRANCE

The breeding season of Atherina boyeri living in the brackish lagoons of Mauguio, Perols and Mejean (Herault, southern France) was very prot racted (February-September). The peak of the reproductive effort occur red in April, May and June. Larger fishes started spawning earlier, an d stopped later, than smaller ones. Batch fecundity varied from 4 to 4 47 oocytes and was positively related to female length and weight. Mon thly mean fecundity increased at the beginning of the breeding season and decreased between June and July. Individual mean oocyte diameter r anged from 1.34 to 1.94 mm and was not related to fish length. Monthly mean oocyte size declined throughout the breeding season as water tem perature rose. There was no trade-off between number and egg size. The strategy of these sand smelts seemed well adapted to ensure spawning success without endangering their survival. The highest reproductive e ffort period occurred in such a way that environmental conditions were suitable to the best survival and growth of hatched larvae. When bree ding ceased, fishes, particularly the youngest ones, had enough time t o improve their condition before overwintering. (C) 1986 The Fisheries Society of the British Isles