Hi-tech tracking of Shoalhaven fish begins

Researchers have released the first of 60 fish fitted with high-tech tracking devices back into the Shoalhaven River as part of a major NSW Government study of their biology, ecology and the effects of environmental flows.

Last Sunday 64 anglers in 34 boats lent a hand to the research by catching more than 200 of the target species for the research, Australian bass and estuary perch.

The anglers were from the Southern Bass Fishing Club and the Basin Lure and Fly Clubs and they held a fishing competition to help catch some of the fish needed for the study.

NSW Department of Primary Industries (DPI) fisheries researcher Chris Walsh said conditions were perfect and the size of the catch exceeded expectations.

"We were able to cull the fish back to the 40 that would be best suited to the research, and the rest were measured and released back into the area they came from."

Transmitters were surgically inserted into 20 fish, which were then released, and another 20 are being kept in holding tanks at the Wollongong University prior to their release in about two weeks.

Mr Walsh said the bass were found in the upstream parts of the Shoalhaven, indicating that they may be heading towards fresher water.

Last week listening stations were placed along the river, and these will be used to monitor and log the fishes’ movements; every time a tagged fish passes a listening station its unique code is recorded.

"This will help us confirm, for instance, that the bass are now undergoing their return migration to fresher water, after having come down to the estuary to spawn in winter."

Mr Walsh said the movements of the tagged fish will be monitored over the next two spawning seasons.;

There is limited knowledge of the migration cues, including timing and location of spawning of either species in the Shoalhaven; hence the researchers will examine inter-annual movements and annual spawning migrations, and the relationship with salinity levels and river discharge.

Two parallel studies are being undertaken. One is by NSW DPI and Wollongong University on the biology and ecology of Australian bass and estuary perch in the Shoalhaven. This is also supported with funds from anglers through the NSW Recreational Fishing Saltwater Trust.

A second study by the Department of Water and Energy is investigating the effects of environmental flows on the upstream migration of native fish.

The NSW Government announced a revised environmental flow regime for the Shoalhaven River earlier this year to better protect flows in the river system and provide an additional 30 GL of water per year for Sydney by harvesting of high flows.