Preliminary Investigation of Mitochondrial-Dna Variation in Jack Mackerel (Trachurus-Declivis, Carangidae) From South-Eastern Australian Waters

A preliminary investigation of the genetic structure of jack mackerel (Trachurus declivis, Carangidae) in south-eastern Australian waters was conducted by using restriction enzyme analysis of mitochondrial DNA (mtDNA). Seventy-five jack mackerel samples were collected from two localities: off Eden in New South Wales and off south-eastern Tasmania. Fish were sampled twice at each locality. Mitochondrial DNA was extracted from developing ovary tissue and heart tissue. The 75 jack mackerel samples were screened with 11 six-base and four four-base enzymes. The level of genetic diversity in jack mackerel was low. The six-base enzyme analysis found limited evidence of reproductive isolation between New South Wales and Tasmanian samples of jack mackerel. However, an analysis of a subset of 42 jack mackerel with four four-base enzymes found evidence of temporal differences in the mtDNA diversities of two Tasmanian samples of jack mackerel