Determination of management units for grey mackerel fisheries in Queensland and the Northern Territory
Damien Broderick, Jenny Ovenden and Raewyn Street
Supported by funding from the Fisheries Research and Development Corporation (FRDC) on behalf of the Australian Government ( 2005/010).
The project revealed that the most appropriate spatial scale for grey mackerel (Scomberomorus semifasciatus) fishery management and monitoring by state or territory, and by regions within these jurisdictions. The project identified at least five separate stocks of grey mackerel throughout northern Australia for management purposes: a Western Australian stock, a north-west Northern Territory stock, northern and southern Queensland east coast stocks, and the likelihood of at least an eastern and western Gulf of Carpentaria stock. This will provide the basis for reliable and robust assessment of the status of grey mackerel stocks and help deliver sustainable harvest and profitable utilisation of grey mackerel resources in northern Australian waters.
In the study we used analyses of genetic (mitochondrial DNA and microsatellites), parasite, otolith stable isotopes, and growth data to determine the stock structure of grey mackerel. Integration of the results from all techniques identified at least five grey mackerel stocks across northern Australia for management purposes and documented differences in growth parameter estimates for some of these stocks. The use of a holistic approach was a powerful tool in providing greater certainty about the stock structure of grey mackerel enabling the identification of adult stocks of fish despite evidence of genetic interchange.