Project number: 1994-168
Project Status:
Completed
Budget expenditure: $52,340.00
Principal Investigator: Stephen Donnellan
Organisation: SARDI Food Safety and Innovation
Project start/end date: 29 Jun 1995 - 30 Mar 1997
Contact:
FRDC

Objectives

1. To use molecular techniques to identify structuring in snapper in SA waters and discriminate between any stocks that may be present

Final report

ISBN: 0 7308 5808 1
Author: Dr Stephen C. Donnellan
Final Report • 1996-12-03 • 1.08 MB
1994-168-DLD.pdf

Summary

The snapper (Pagrus auratus) fishery in South Australia is currently managed as one stock, although recent changes to the regional management of the recreational fishery have been based in part on an assumption of a multi-stock population structure.  Tagging and genetic studies in other States have shown that different stocks do occur over relatively small geographical areas.  This prompted an interest in identifying the existence or otherwise of separate stocks in South Australian snapper.  An urgency to identify the appropriate spatial management units for this species has been prompted by the decline of the commercial catch to its lowest levels since 1968.

Studies of genetic variation in the proteins and DNA of snapper were carried out at the South Australian Museum to determine the presence of genetically isolated breeding stocks. Fish from each of the three commercially fished areas within the state and from Victoria and Western Australia were sampled over a 5 year period with assistance from commercial and recreational fishers.

The present genetic study provided no evidence of the existence of more than one stock in the commercially fished waters in S.A. and  south-western W.A.  This is consistent with tagging studies carried out in South Australia over the past 19 years.  In contrast, both genetic and tagging studies have shown that fish from Port Phillip Bay, Victoria represent a different stock which extends into the south-east of S.A.
The significance of these results is that the snapper fishery in S.A. should be managed as a single genetic stock. Ultimately, final management of the fishery will incorporate other scientific and economic parameters, but will have a stronger biological basis because of the availability of these genetic data.

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