Sand flathead remains one of Tasmania's most popular recreational fish species, but the latest assessment shows the stock is still
highly unsustainable.
Current status: Depleted
The stock remains classified as Depleted. This means there are not enough large females to ensure healthy reproduction and recovery.
Sand flathead has been classified as Depleted since 2020/21. Continued strict management measures and careful monitoring are essential to help the stock recover faster.
View the Institute for Marine and Antarctic Studies Southern Sand Flathead Assessment 2025 (PDF).
What the science shows
Most big fish are gone
Surveys in 2024/25 found that most fish are still small. In many areas, 79–100% of fish were below the legal size (35 cm). In the southeast, only 1% were legal-sized. In comparison 53% of fish (1 in 2) were larger than 35cm around Flinders Island, which has a sustainable population.
There aren't enough big, old, female fish
Big female fish produce more eggs than small young female fish, but most of these big females are gone. That means the ability of the population to produce eggs is significantly reduced – in the south-east, it's down to just 5% of what an unfished population could make.
The technical term for this is
depleted spawning potential. Depleted spawning potential can lead to a population that might no longer have the capacity for stock rebuilding as there are not enough mature adults to reproduce.
The population may be stunted
In heavily fished areas, there's some evidence to suggest sand flathead are growing more slowly and don't grow as big.
Fishing may be removing faster-growing fish that reach the size limit quickly, leaving small, slow growing flathead to breed.
This may lead to
genetic stunting.
Understanding genetic stunting
How quickly sand flathead grow and what size they grow to partly depends on genetics.
Large, fast-growing flathead reach the legal size sooner than small slow growing flathead. This means they get caught younger, and have less chances to breed and pass on their fast-growing genes.
On the other hand, small, slow-growing fish can take years to reach the minimum size limit. This gives them plenty of time to breed and pass on their slow-growing genetics.
Over time, this potentially causes:
- Small, slow growing sand flathead to become more common.
- The average size of sand flathead to get smaller.
Watch the video below for an explanation of genetic stunting in fish stocks.