No abstract

Morphometric variation was used to examine the stock structure, in southern Australian waters, of the deepwater marine teleost Hopiostethra utiunlicus, orange roughy. Seven siiinples were collected from non-spawning aggregations in [1989][1990]. Three samples were also collected in the winter of 1992, two from the main spawning site off the eastern coast of Tasmania (St Helens), and the third from the other main fishing ground south of Tasmania. The 38 morphometric measurements taken from each of over 1300 fish were size-standardized by an allometric formula and analysed by univariate and multivariate statistics. The results indicate significant variation in the morphology of orange roughy caught from geographlcally distinct aggregations. They further suggest that the main spawning aggregation may consist of fish from diKerent groups at different times of the spawning period. There appear to be at least seven morphologically distinguishable stocks of orange roughy in southern Australian waters, despite genetic data indicating appreciable levels of gene flow between them.

No abstract

Phenotypic sex in salmonids is determined primarily by a genetic male heterogametic system; yet, sex reversal can be accomplished via hormonal treatment. In Tasmanian Atlantic salmon aquaculture, to overcome problems associated with early sexual maturation in males, sex-reversed females are crossed with normal females to produce all female stock. However, phenotypic distinction of sex-reversed females (neo-males) from true males is problematic. We set out to identify genetic markers that could make this distinction. Microsatellite markers from chromosome 2 (Ssa02), to which the sex-determining locus (SEX) has been mapped in two Scottish Atlantic salmon families, did not predict sex in a pilot study of seven families. A TaqMan 64 SNP genome-wide scan suggested SEX was on Ssa06 in these families, and this was confirmed by microsatellite markers. A survey of 58 families in total representing 38 male lineages in the SALTAS breeding program found that 34 of the families had SEX on Ssa02, in 22 of the families SEX was on Ssa06, and two of the families had a third SEX locus, on Ssa03. A PCR test using primers designed from the recently published sdY gene is consistent with Tasmanian Atlantic salmon having a single sex-determining gene that may be located on at least three linkage groups.

Seven novel oligonucleotide primer pairs for polymerase chain reaction amplification of introns from nuclear genes in coelomates were designed and tested. Each pair bound to adjacent exons that are separated by a single intron in most coelomate species. The primer sets amplified introns in species as widely separated by the course of evolution as oysters (Mollusca: Protostoma) and salmon (Chordata: Deuterostoma). Each primer set was tested on a further 6 coelomate species and found to amplify introns in most cases. These primer sets may therefore be useful tools for developing nuclear DNA markers in diverse coelomate species for studies of population genetics, phylogenetics, or genome mapping.