RESEARCH conducted by NSW Department of Primary Industries is providing further insight into the movements and spawning behaviour of estuary perch in the Shoalhaven River.
“Listening stations” deployed within tidal reaches have recently shown that individually tagged estuary perch, of both sexes, make several downstream migrations (up to 30km) during winter.
The resulting spawning aggregations are primarily formed in very localised areas near the estuary mouth. Tracking of tagged estuary perch showed they preferred specific habitats for spawning, including large wooden snags, submerged rock walls, and artificial (concrete) structures.
All of these habitat types are located close to deeper and faster flowing river sections. Plankton tows within these areas showed much higher numbers of estuary perch eggs were collected at night during the first two hours of the run out tide, indicating spawning was occuring at this time.
From these results, reserachers have concluded that estuary perch are selecting structurally complex habitat in which to congregate and disperse their eggs seaward. Therefore, this indicates the removal of snags in the past may have resulted in the restricted distribution observed for this species.
