Native fish stocking of rivers:

Discriminating between hatchery-reared and wild fish

Native fish populations in the Murray-Darling Basin have undergone severe declines since the development of regulated river flows for irrigation, domestic water supplies, and hydro-electricity. Stocking of fish has been widely used in attempts to restore native fish populations for recreational fishing and conservation purposes. However, little is known about the fate of the stocked fish or the effects of stocking on resident populations. This project will develop and evaluate protocols for chemical marking otoliths of hatchery-reared fish (golden perch) so that their source can be determined. Hatchery-reared golden perch will be experimentally stocked in rivers and the population structure and abundance will be compared between stocked and unstocked rivers. Natural chemical signatures in the otoliths will also be used to determine important recruitment areas in the Murray Darling Basin. The outcomes of this project will allow fisheries managers to make informed decisions regarding stocking strategies and the relative effectiveness of stocking versus natural recruitment. This is a collaborative project involving the University of Adelaide, Victoria Department of Sustainability and Environment, and New South Wales Fisheries.

Objectives

• Develop and evaluate otolith marking protocols to batch mark hatchery-reared fish so that their source (individual hatchery, year of production) can be readily determined.
• Use chemical analyses of otoliths to examine the chemical "signatures" of naturally reared fish (i.e. wild fish) to determine whether these can be used to identify important sources of natural fish recruitment in the Murray-Darling Basin.
• Compare population structure and abundance in experimentally stocked rivers to that in un-stocked reference rivers.
• Determine the proportion of hatchery-reared fish versus wild fish in rivers within the Murray-Darling Basin.

Personnel

Dr Andrew Munro (Environmental Biology; University of Adelaide)
Dr Bronwyn Gillanders (Environmental Biology, University of Adelaide)
Dr Dave Crook (Victoria Department of Natural Resources & Environment) - www.dse.vic.gov.au\ari
Dr Andrew Sanger (New South Wales Fisheries) - www.fisheries.nsw.gov.au

Funding

Australian Research Council Linkage Grant
University of Adelaide
Victoria Department of Sustainability and Environment
New South Wales Fisheries.