2010/725 Capturing and maintaining genetic diversity for the establishment of a longterm breeding program for Barramundi (Lates calcarifer) aquaculture

By Shannon Loughnan

Barramundi is naturally a mass spawning species, which can be induced to spawn in captivity under conditions that attempt to replicate the natural environment. The Australian Barramundi industry has on hand a large number of mature broodstock that are currently supplying the grow-out market, however, before selective breeding programs can begin, it is important to assess the levels of genetic diversity and relatedness of current captive broodstock populations.

Mass spawning hatchery practices using small broodstock populations, in addition to the cannibalistic nature of some fish species, contribute to a reduction of genetic diversity from parent to offspring and throughout the juvenile grow-out stages. This is of concern when establishing a selective breeding program for such species because the genetic diversity that is captured in the start-up and initial generations of the program is the basic ingredient for future genetic improvement. The aim of this thesis was to examine methods for capturing and conserving genetic diversity in mass spawning Barramundi (Lates calcarifer), when constructing a base population for a long-term selective breeding program for the species.

The results suggest that a mass spawning group of at least 30 Barramundi individuals is required to achieve a high participation rate of breeders and to limit the loss of genetic variation transferred to the offspring. Options for selecting candidates to compose a founding population were explored, and recommendations made to promote the longevity and impact of a selective breeding program for Barramundi.