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

Abstract

A bioeconomic simulation model for Lates calcarifer predicted that a strategy involving crossing current generation males with previous generation females would be a practical, e¡ective and pro¢table 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 161 9% 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 bene¢t^cost ratio (13:1 versus 7:1after 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 ¢xed 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 pro¢table than those producing 100 families.

Improving the utility of genetic markers in fish populations

“…Previously published papers showing genetic gains for barramundi could not be identified and only one simulated breeding program has recently been reported (Robinson et al, 2010). At the onset of any new breeding program in aquaculture there is much to be gained by assessing wild genetic diversity as different strains may be more suitable for commercial production.…”

“…In comparison with the model proposed by Robinson et al (2010), which requires 100-200 broodstock (50-100 full-sib families), the new design described in this chapter would require 72-96 broodstock assuming three to four broodstock per family were maintained to guarantee selection of two offspring from each of the 24 families. Therefore the costs of maintaining broodstock in the new program could be as little as half of that proposed by Robinson et al (2010).…”

“…In an alternative barramundi breeding program designed with a different set of constraints Robinson et al (2010) reported a 7.1% gain per generation. The progeny test design (Figure 2.2) is capable of identifying in just two years superior broodstock with breeding values that could take between, 3.0 and 7.2 generations to achieve with this alternative design, or 9 to 22 years assuming a three year generation interval.…”

“…This application encompasses kinship analysis using genotype samples from the heaviest fish to identify pedigree relationships. In fish species walkback selection has been proposed by Sonesson (2005) and Robinson et al (2010).…”

“…At the onset of any new breeding program in aquaculture there is much to be gained by assessing wild genetic diversity as different strains may be more suitable for commercial production. The walk-back selection program for growth rate proposed by Robinson et al (2010) did not attempt to evaluate the potentially diverse strains from different geographic locations prior to breeding. In species other than barramundi regional sampling of strains has revealed a 52% difference between low and high growth in six strains of Labeo rohita (Reddy et al, 2002), a 73% difference in weight in five strains of Onorhynchus mykiss (Overturf et al, 2003) and a 104% difference in weight at 105 days between Abbassa and Maryout tilapia strains (Elghobashy, 2001).…”