Southern Sand Flathead Platycephalus bassensis

Victoria 

Southern Sand Flathead historically comprised a significant component of the commercial catch in Victoria, with more than 200 tonnes (t) taken annually for several years until the 1950s from Port Phillip Bay². This species has also been an important component of the recreational fishery, with an estimated 322 t caught during 2000–01^3,4. Using three independent measures of abundance (biomass estimates from fishery-independent trawls, commercial longline catch per unit effort and recreational catch per unit effort), an 80–90 per cent decline in stock size was detected over the period 2000 to 2010³. By 2013, stocks had recovered to 30 per cent of 1990s levels, but the abundance of zero-plus aged fish has remained very low since 1994.

Very little is known about the catch of Southern Sand Flathead from Victorian waters outside of Port Phillip Bay, except that they are taken as bycatch and generally not targeted by commercial fishers. Some targeting offshore by recreational anglers is known to occur.

There is no formal management plan and no limit reference point for Victorian Southern Sand Flathead. Despite the substantial decline in biomass for the period 2000 to 2013 and the significant decline in recruitment for Port Phillip Bay populations³, there is no evidence that these trends are caused by the removal of catch. The above evidence indicates that the biomass of this stock has been deteriorating but is not likely to be recruitment overfished.

Recruitment in Port Phillip Bay is heavily influenced by climatic conditions^2,3,5, and for many years it was suggested that existing levels of fishing pressure had little influence on spawning success⁵. This is partly because a portion of the population will not grow to a size at which they become vulnerable to fishing (that is, they will not reach the legal minimum size). A more recent study, undertaken in response to angler concerns about the decline in Southern Sand Flathead abundance, found that, despite the decline in abundance, stock exploitation levels between 2000–01 and 2006–07 remained stable, at 15–30 per cent of the stock biomass³. This study found that the magnitude of the decline was, however, unprecedented over the history of the fishery and that, under these circumstances, fishing pressure can contribute to a more rapid decline or potentially affect the recovery rate of the stock. Consequently, the study evaluated management options to assist the recovery of the fishery in Port Phillip Bay.

The current level of fishing pressure is considered to be relatively low from the commercial sector, and is unknown for the recreational sector. The proportion of the population that exceeds the current minimum legal size limit (27 cm) has steadily increased from 1990 to 2011. In the early 1990s, the percentage of legal sized fish was less than 10 per cent of the population. This proportion was more than 30 per cent by the early 2000s and remained above 20 per cent until 2011. The remaining 70–80 per cent of the population are too small to be harvested by recreational fishers. From the above evidence, it is not clear whether the current level of fishing pressure is likely to cause the stock to become recruitment overfished. Hence, there is insufficient information available to confidently classify the status of this stock.

On the basis of the evidence provided above, Southern Sand Flathead in Victoria is classified as an undefined stock.  

Tasmania 

In Tasmanian waters, Southern Sand Flathead are mainly landed commercially by hook-and-line fishers, with minor catches taken by gillnet and Danish-seine. Total landings are low, typically less than 15 t per year⁶. Recreational catches of Southern Sand Flathead are substantially higher (around 300 t); the species dominates the recreational fishery in terms of overall catch numbers and weight⁷. Catch-curve analysis suggests that exploitation rates of legal sized fish are highest in the south-east of the state, and there are anecdotal reports of declining catch rates in some areas. However, juvenile fish appear to be abundant, and the legal minimum length is set well above the size at maturity to prevent recruitment overfishing ⁶. Because of a lack of quantitative commercial fishing data and uncertainty surrounding the activities of the recreational fishery, there is currently insufficient information available to confidently classify the status of this stock.

On the basis of the evidence provided above, Southern Sand Flathead in Tasmania is classified as an undefined stock.