Genetics unravels the complexities of commercial prawn breeding
The practicalities of rearing aquaculture species commercially, including the black tiger prawn here in Australia, means that thousands of offspring are often reared together with large variability in the number of offspring contributed from each family. However, this presents a significant challenge for geneticists who are trying to maintain genetic diversity within the breeding population, while also selecting the best performing families to create the next generation. This results in significant costs associated with the collection of reliable performance data (such as growth or survival) from hundreds of families grown across different ponds and production sites.
This study, as part of the ARC Hub for Advanced Prawn Breeding, tracked three separate groups of prawns produced using a communal spawning and rearing approach under commercial conditions. At two ages (1 month and 5 months), thousands of individuals were identified using CSIRO’s parentage marker panel and allocated to their family groups. Although large numbers of families were identified, results at 1 month showed that there was a massive bias towards some families, while others had only a few individuals, most likely from uneven contributions of offspring from each family at the beginning. Large changes in the prevalence of many families were also detected from 1 to 5 months of age, allowing us to see which families had a greater survival relative to other families under commercial production conditions. This technique of reviewing family distribution with early life stages is a useful consideration when selecting for families that survive better or are more robust in this environment.
The impact of this work was realised by modelling the effect of sample size on the ability to accurately determine changes in family proportion during commercial growout. This suggested that there is a balance between the detection of rare families, the numbers of individuals within each family to obtain accurate performance data, and the costs of individual genetic identification. Ideally, practical strategies to reduce the variability in family contributions may be applied in the hatchery, through individual or smaller group spawnings and rearing, allowing more even contributions of offspring from each family. By sampling 500 individuals per pond, accurate rankings for growth and survival were determined for the majority of families, and allowed the top performing candidates to be identified under commercial conditions.
This study demonstrates that a greater investment at the hatchery, to understand and equalise what goes into a prawn pond, will save a lot of effort collecting and analysing individuals as they are harvested, in order to identify the best families for selection. With studies such as these we’re breaking down the complexity of prawn breeding to make it easier for producers to efficiently deliver high quality prawns that get better every year.
These studies were recently published in Frontiers in Genetics.
CSIRO Aquaculture contact
Dr Andrew Foote – Research Scientist
Dr Nick Wade – Senior Research Scientist
