Fishing Australia

An innovative project to study Murray cod is underway, thanks to $50,000 in funding from the NSW Recreational Freshwater Fishing Trust, Industry and Investment NSW, Principal Research Scientist Grafton Institute, Dr Stuart Rowland, said today.

“Murray cod, the largest freshwater fish in Australia, is an iconic species with cultural and historical significance. It is a premier recreational fish that is now listed as a vulnerable species by the  Commonwealth Government,” Dr Rowland said.

“A number of factors have contributed to the decline of Murray cod, including over exploitation by commercial and recreational fisheries, predation by introduced fish, and habitat degradation.

“This research project will determine key aspects of Murray cod reproduction in selected parts of the northern Murray-Darling River System. The project will complement various management  programs based on research findings that have already been undertaken during the past two decades to promote a recovery of Murray cod.”

“Murray cod is the key native freshwater recreational species in NSW, and any information that can contribute to improved management will ultimately enhance stocks of Murray cod and directly benefit recreational anglers.

“Most of the previous research on Murray cod has been done in southern tributaries of the Murray-Darling System, and there are potentially significant differences between cod populations in  southern and northern areas. Consequently it is important to study cod in the northern tributaries to ensure efficient management across the entire system.

“Our project will provide information on the movement of adult fish, the type and location of spawning sites, spawning behaviour, parental protection of eggs and larvae, effects of coldwater pollution, and the timing and duration of the breeding season in the northern tributaries.

“In addition, the project may provide information on an important, much debated and at times emotive aspect of Murray cod reproductive biology: do very large Murray cod (e.g. greater than 100 cm) breed and contribute to the reproductive output of the species? There is some evidence that large cod may not be active and/or successful breeders; however, the issue hasn’t been fully investigated in the wild.”

The funding will be used to select rivers and study sites in different habitat types (e.g. upland and lowland), purchase tags and equipment, and enable collaboration with recreational fishers and fishing groups, scientists and managers, and staff of other fisheries agencies.

“Intensive fish surveys will be done at each site using a boat-mounted electrofishing unit to determine species present, and the size frequency and age structure of Murray cod,” Dr Rowland said.

“Radio tags will be surgically implanted in individual cod and used to monitor their movements and behaviour at each site. Some large cod, greater than 100 cm will be tagged in an attempt to determine their reproductive contribution. In addition, underwater cameras will be strategically located to observe fish and their breeding behavior.”

This research project has the support and co-operation of the Queensland Department of Primary Industries & Fisheries, the University of New England, the Native Fish Strategy, the Queensland Murray-Darling Basin Committee, the Murray-Darling Basin Authority, and recreational fishers and fishing clubs.

Rob Paxevanos