ELECTROPHORETIC CHARACTERIZATION OF MULTIPLE GENETIC STOCKS OF BARRAMUNDI PERCH IN QUEENSLAND, AUSTRALIA

We investigated the amount and pattern of genetic variation expressed by the barramundi perch Lates calcarifer throughout Queensland to iden tify and characterize population subdivision. Fourteen loci known to b e variable in this species were screened in 2,912 fish from 24 differe nt areas in Queensland by means of horizontal starch gel and slab poly acrylamide gel electrophoresis. Eleven loci were used in the statistic al analysis of stock structure. Seven of these loci (EST-2, ESTD*, mI DHP, sIDHP*, LDH-C*, PGDH*, and PROT*) were polymorphic at the 0.95 l evel (frequency of the most common allele was 0.95 or less) in at leas t one collection; four loci (IDDH, FH*, sMDH-A*, and PGM*) were polym orphic at the 0.99 level. Genotype proportions at these 11 loci exhibi ted close agreement with Hardy-Weinberg expectations. An overall chi-s quare test of allele frequencies revealed substantial genetic heteroge neity among the 24 collections. Successive rounds of contingency chi-s quare tests involving geographically adjacent pairs of collections wer e conducted to identify individual genetic stocks and to locate inters tock boundaries. Seven genetically distinct stocks of Queensland barra mundi perch were identified by this process. Similar tests demonstrate d that Queensland stocks were distinct from neighboring stocks in the Northern Territory of Australia and in Papua New Guinea. The considera ble genetic differentiation of barramundi stocks demonstrated by this analysis has important implications for fishery management, aquacultur e, and conservation of this species.