MULLOWAY STOCKING IN NEW SOUTH WALES

Mulloway is one of only a few marine species to be stocked in New South Wales. The first marine stocking was undertaken early last century, with the release of some few thousand flounder in Port Hacking by the then chief fisheries scientist, ABC Dannevig. Dannevig was a Norwegian fisheries scientist that was brought over by the government to head up the then Commonwealth Department of Fisheries. The flounder unfortunately were never seen again. Since then, very little has been done with respect to stocking of marine species in this state, and there have never been any ongoing marine stocking programs.

Mulloway stocking pilot investigations commenced in 1996, with the release of hatchery-reared mulloway into Swan Lake, Khappingghat Creek and Smiths Lake. Some positive results, good survival and recruitment to the fishery of mulloway stocked in Smiths Lake led to additional pilot studies aimed at evaluating the ecological cost of stocking mulloway. The ecological cost is the prey resources in the system that stocked fish consume to grow and recruit to the fishery. Stocking experiments in the second project were undertaken in Smiths Lake and the Georges River. Unfortunately, this second series of stockings in Smiths Lake were not as successful as the previous stockings, with very few stocked fish surviving to the fishery.

NSW Fisheries 6000L transporter, at one release site in the Georges River/Botany Bay.

Further investigations indicated that the reasons behind the poor performance of the latter mulloway stocking in Smiths Lake were lack of habitat and ideal forage resources. Juvenile mulloway prefer deep hole habitat and mysid shrimp as a prey resource, however Smiths Lake has neither. Positive results were obtained from the Georges River stockings however, with fish surviving and recruiting to the recreational fishery. These stockings have led to the development of a model with which to estimate appropriate stocking density based on the area of key habitat in a system and consumption requirements. Now mulloway pilot stockings aim to validate estimates obtained from this model, and resolve other factors that may contribute to better survival and lower ecological impact, such as season and site of release, release technique and genetic impacts of stocked fish. The data obtained from these experiments will be applicable to stocking of other species. Below is a summary of mulloway stocking in New South Wales to date.

80 mm juvenile mulloway fingerlings being released into Smiths Lake in 2003.