Testing the feasibility of stocking Sand Flathead, Snapper and Estuary Perch has demonstrated the benefits enhancement can have in supporting conservation and climate-driven opportunities for Tasmania’s recreational fisheries.

Tasmania’s recreational fishery is a cornerstone of community life, with one in four residents taking part each year. With a recent statewide survey finding more than 830,000 finfish retained and 1.2 million either released or discarded annually, recreational fishing delivers significant social and economic value. However, some key fish stocks are under pressure. 

That’s why FRDC project 2023-163, led by the University of Tasmania’s Institute for Marine and Antarctic Studies (IMAS), is assessing the feasibility of using hatchery-reared fish to enhance stocks of three key species: Southern Sand Flathead (Platycephalus bassensis), Snapper (Chrysophrys auratus) and Estuary Perch (Percalates colonorum).

Southern Sand Flathead is Tasmania’s most popular recreational species accounting for approximately 50 per cent of all finfish retained by recreational fishers across the state. Sustained recreational fishing pressure over several decades has led the fishery to be classified as depleted in Tasmania as per the Status of Australian Fish Stocks Reports released in July 2024. As a result, recent management interventions have seen bag limits reduced (from 20 to two fish per day in some regions) and introduced new size limits.

While these management reforms should support natural recovery, rebuilding biomass could take many years. That’s why stock enhancement is emerging as a potential additional management tool, to complement traditional fisheries management strategies.

The D’Entrecasteaux Channel south of Hobart was chosen as an ideal area to assess the feasibility for stock enhancement for Southern Sand Flathead. This sheltered, popular waterway is a hotspot for recreational fishing, but decades of heavy fishing have left the stock depleted, with fewer large fish and a stunted population structure.

The project uses EnhanceFish, a modeling tool developed by the University of Florida, to assess different fish release scenarios. Results showed that releasing larger juvenile flathead (greater than nine cm) delivers the greatest survival gains and boosts biomass more effectively than smaller fish. Importantly, proactive stocking also offers a chance to reintroduce more physically robust and diverse flathead, potentially counteracting the long legacy of size-selective fishing.

“Southern Sand Flathead are at the heart of recreational fishing in Tasmania, and we want to maximise the value of these species to the community,” says project co-investigator Sean Tracey, who leads the fisheries and aquaculture centre within IMAS. 

“Successfully enhancing Sand Flathead stocks in the D’Entrecasteaux Channel, alongside strong management to control fishing effort, would deliver real benefits for the community, given how popular this waterway is with local fishers. Stocking isn’t a silver bullet, but it could play a role alongside tighter management to help this fishery recover faster.” 

Snapper on the rise

While flathead stocks struggle, Snapper is on the way up. Warmer coastal waters have seen the species steadily expand into Tasmanian waters, particularly around the southeast coast. This climate-driven shift creates a proactive opportunity: could stocking boost Snapper numbers and provide fishers with an exciting alternative target species?

Model results suggest it could. Releasing Snapper at 10 cm generated a 36 per cent higher biomass increase than releasing at four cm, with strong gains even at moderate stocking numbers. At higher release levels, hatchery fish could equal or surpass the biomass contribution of wild fish.

"Snapper enhancement in Tasmania isn’t about rebuilding a depleted fishery, it’s about planning for the future,” explains Sean. “As waters warm, this iconic species is going to become a big part of our fishery, and enhancement could help that transition.”

The final case study looks at Estuary Perch, a species now confined in Tasmania to a single population in the Arthur River. While prized by mainland anglers, its local population is small and genetically distinct. Enhancement here is less about boosting catches and more about safeguarding a vulnerable stock.

Model outputs show that release size is critical. Stocking eight cm juveniles delivers exponential biomass gains compared to smaller fish. Under minimal fishing pressure, enhancement could help stabilise and expand the Arthur River stock and potentially support new “insurance” populations in other river systems the species used to inhabit.

“This is about conservation first, but it could also open the door to carefully managed recreational opportunities in the future,” says Sean. 

The project emphasises that stock enhancement has potential as part of a broader toolkit: rebuilding depleted stocks like Southern Sand Flathead, supporting climate-driven newcomers like Snapper, and conserving vulnerable species like Estuary Perch. The team remains mindful of ecological displacement and biosecurity concerns, which are managed through broodstock care, monitoring, and adaptive management.

As Tasmania looks to the future of its recreational fishery, enhancement may complement management reforms. This would help ensure that Tasmanians continue to enjoy a sustainable, rewarding fishing experience for generations to come.

Related FRDC Project

2023-163: Feasibility of recreational scalefish enhancement in Tasmania