The influence of temperature on the onset of first maturity in sea bass

Oocyte development was aborted and full maturity did not occur in virgin fe male sea bass Dicentrarchus labrax unless they remained in water above 10 d egrees C during the main period of gonad development. There was no differen ce in the condition factors of females with high or low I,values in March, which indicates that retarded gonadal development was not necessarily due t o poor body condition or nutritional state. It is suggested that the extend ed duration of the adolescent phase of female bass around southern Britain is a response to their environment, rather than an intrinsic aspect of the species' biology. (C) 2000 The Fisheries Society of the British Isles.