Modelling selective breeding in protandrous, batch-reared Asian sea bass (Lates calcarifer, Bloch) using walkback selection

A bioeconomic simulation model for Lates calcarifer predicted that a strategy involving crossing current generation males with previous generation females would be a practical, effective and profitable way of dealing with protandry when batch rearing for selective breeding to improve the growth rate. The strategy allowed earlier initialization and more frequent ongoing rounds of selection, and resulted in a 16-19% higher overall response, than an alternative where each generation's males were crossed with the same generation's females. The strategy also yielded the highest short-term benefit-cost ratio (13:1 versus 7:1 after 8 years of selective breeding) and the highest short- and long-term value for participants in a breeding cooperative (a net present value of AU$28 million and an internal rate of return of 144% over 10 years), due to higher yields per fixed costs of production per unit area and due to savings in feed costs per kilogram of production. Breeding facilities of scale producing 50 full-sibling families per generation were found to be more profitable than those producing 100 families.