Project number: 1991-032
Project Status:
Completed
Budget expenditure: $108,560.00
Principal Investigator: Ronald E. Thresher
Organisation: CSIRO Oceans and Atmosphere Cleveland
Project start/end date: 2 Oct 1991 - 1 Oct 1993
Contact:
FRDC

Objectives

1. Compare the stock structure of Jackass morwong in Aust waters as indicated by 4 techniques.
2. Determine the number of Aust stocks & distribution, & if Jackass morwong in Aust & NZ coastal waters are parts of the same stock

Final report

Author: Ron Thresher Robert Ward
Final Report • 1993-10-01 • 2.83 MB
1991-032-DLD.pdf

Summary

Four different techniques for determining the stock structure of a marine fish species were compared, using as a subject the jackass morwong. The four techniques examined were allozyme analysis, mitochondrial DNA analysis and two techniques based on measuring the composition of otoliths ('ear stones') - electron probe microanalysis and proton probe microanalysis, each of which measures the concentrations of different sets of elements. The comparison was based on all four techniques being applied to the same samples, obtained from 14 sites distributed geographically from Perth to NZ.

The principal result was that both genetic techniques distinguished between NZ and Australian samples, indicating strongly at least two genetically distinct stocks. The otolith analysis, however, suggested much greater structuring of the Australian samples, and suggests perhaps four stocks in Australian waters: off NSW and Victoria, off southern Tasmania, in the Great Australian Bight, and off Western Australia. There appears to be considerable mixing of individuals among sites, however, at least some of which appears to be the result of large scale seasonal movements of stocks. Otolith analysis could not separate the southern Tasmanian and NZ samples, which could be either because the environments in which the fish develop are similar in the two areas or because they are the same stock. Although the genetic analysis does not separate the southern Tasmanian sample (Maatsuyker) from other Australian sites, in practice sample size for genetic analysis of this site is too small for an effective comparison and, therefore, the genetic affinities of the SW Tasmanian and NZ stocks are not yet clear.

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PROJECT NUMBER • 2023-085
PROJECT STATUS:
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Snapper Science Program: Theme 1 - Biology and Ecology

1. Quantify the abundance of age 0+ Snapper in northern Spencer Gulf and Gulf St Vincent to provide relative estimates of recruitment for 2024, 2025, and 2026. Examine the otoliths of these fish to improve the understanding of early life history processes.
ORGANISATION:
Flinders University