Alternate Title

Seasonal Variation of Reproduction and Fattening in Gulf Killifish from Brackish Mariculture Ponds


Seasonal changes in gonadal indices, plasma androgens in males, plasma estrogens and egg production in females, and body fat content in both sexes were monitored in gulf killifish, Fundulus grandis, reared in mariculture ponds. Changes in plasma androgens (males) and estrogens (females) were positively correlated with changes in gonadosomatic indices (GSI) of both sexes during most of the year. Seasonal variation in the GSIs of a nearby natural marsh population were similar, though not identical, to that of the pond-raised population. However several distinct differences were noted between these two populations: 1) spawning was prolonged in the mariculture population as compared with the wild population; 2) body fat content of the mariculture fish was significantly greater than wild fish during all seasons of the year; 3) a significant negative correlation between the seasonal cycles of body fattening and reproduction was observed in the mariculture fish but not in the wild fish. These data indicate that the mariculture environment and resultant high levels of body fattening supported prolonged spawning in this species.