Sexual development in fishes is highly plastic relative to that of humans and most other vertebrates. Center researchers are studying the process of gonadal differentiation (i.e., development of ovaries versus testes) in sablefish from a basic perspective and are also conducting studies on how to control this process to improve aquaculture sustainability and economics. All-female production of sablefish is a near-term goal that would capitalize on the more rapid growth of females relative to males and immediately benefit sablefish aquaculture. Our longer-term objective is to develop approaches for production of reproductively sterile sablefish, which would mitigate risks of escapement of farmed fish into the wild. We are also exploring approaches to avoid hormone treatment of fish for human consumption or transgenesis.