Population genetic structure of the catadromous Australian bass from throughout its range

One hatchery-derived impoundment and nine wild riverine populations of the catadromous percoid Australian bass Macquaria novemaculeata were examined at six polymorphic allozyme loci to reveal population genetic structure. Subtle genetic differences among many populations indicated that fish did not interact as a panmictic unit, but rather conformed to an isolation by distance pattern of population structure. The hatchery-derived Glenbawn Dam sample differed from the riverine populations in both average heterozygosity and number of polymorphic loci, demonstrating the need for caution in supplementation programs to rehabilitate wild riverine populations.