IMPROVING PRODUCTION EFFICIENCY OF SEA BASS FARMING BY DEVELOPING METHODOLOGIES TO ELIMINATE ENVIRONMENTAL ANDROGENESIS

摘要

The European sea bass (Dicentrarchus labrax) is one of the most important species for aquaculture in Europe. A major constraint in its farming is the occurrence of 70-99 % males in captive stocks. Male-dominant stocks are undesirable, because males exhibit reduced somatic growth compared to females, resulting in 20-40% smaller body weight at harvest. In captivity, males mature normally at two years of age, one year earlier than females, before reaching marketable size. In contrast females, are marketed before reaching first maturation. Therefore, it is desirable to culture predominantly female stocks. To increase females, the easiest method would be the use of estrogens to feminize stocks but consumers would not accept sex steroid-treated fish. In addition, the use of sex steroids in aquaculture poses an obvious environmental hazard. Thus, there is a need to develop a steroid-free method to produce females, one that exploits the sex lability of sea bass in response to environmental factors during early development.