Allozyme variation and stock structure in the black bream, Acanthopagrus butcheri (Munro) (Sparidae) in southern Australia: implications for fisheries management, aquaculture and taxonomic relationship with Acanthopagrus australis (Gunther)
Lw. Farrington et al., Allozyme variation and stock structure in the black bream, Acanthopagrus butcheri (Munro) (Sparidae) in southern Australia: implications for fisheries management, aquaculture and taxonomic relationship with Acanthopagrus australis (Gunther), FISH MA EC, 7(3), 2000, pp. 265-279
An investigation of allozyme variation at 32 loci in the black bream, Acant
hopagrus butcheri (Munro), and the yellowfin bream, Acanthopagrus australis
(Gunther), revealed heterozygosities (H) equal to 0.035 and 0.065, respect
ively, and polymorphism (P-0.95) equal to 0.067 and 0.200, respectively. Th
e genetic data confirm the very high level of genetic similarity previously
found between the two species, but nevertheless also support their recogni
tion as separate species. The finding of only limited allozyme differentiat
ion at three polymorphic loci amongst six black bream samples from south-ea
stern Australia is consistent with the existence of a single panmictic popu
lation in this region. This would require that adult black bream have a gre
ater capacity to survive in near-shore marine environments than previously
realised and that dispersal between estuaries is more extensive than was sh
own by tagging studies. In contrast, significant differences were found at
two loci between black bream from south-eastern Australia and a sample from
south-western Australia. The degree of genetic divergence between stocks i
n south-eastern and south-western Australia suggests that only local brood
stock should be used for aquaculture or re-stocking as a precaution until f
urther investigations with DNA-based techniques are conducted. The genetic
divergence detected supports separate management for populations in Western
Australia and Victoria.