Dusky Flathead Platycephalus fuscus

Queensland

Nominal commercial catch rate has been stable since 1993⁶. Fishery-dependent monitoring from 2007 to 2013 indicates that both the commercial and recreational fishery sectors are harvesting Dusky Flathead across a spread of lengths and ages⁶. Fishery-dependent monitoring of length and age indicates that Dusky Flathead populations have variable recruitment, with no evidence of a decline through time⁶. The evidence indicates that the biomass of this stock is unlikely to be recruitment overfished.

In the commercial fishery, nominal effort continues to decrease (5408 days fished in 2009; 4100 days fished in 2013)⁶. Recreational anglers were estimated to have targeted Dusky Flathead on more days in 2013 (163 580 days) than in 2000 (147 580 days). Commercial and recreational fishers predominantly harvest female fish because of the minimum and maximum size limits that are in place. The minimum size protects most male fish, and the maximum size protects large female fish⁶. Possession limits are in place for the recreational sector. Mouth-hooked Dusky Flathead have high post-release survival⁷. Estimates of total mortality (from catch curves) are high—the fishing mortality rate (F) is greater than the natural mortality rate (M)—but show no clear trends upwards or downwards since 2007⁶. The estimates do not take into account older fish, which are known to exist in the population but are protected by the upper size limits in place. The current level of fishing effort is unlikely to cause this stock to become recruitment overfished.

On the basis of the evidence provided above, Dusky Flathead in Queensland is classified as a sustainable stock.  

New South Wales

Median commercial catch rates (nominal) of Dusky Flathead in New South Wales have been relatively steady for the past 5 years, and slightly higher than those observed in the previous 11 years (1997 to 2013)⁸. There is some temporal and spatial variability in the length compositions of the landings for this species, which is indicative of a stock with variable recruitment. This pattern has been the same since the 1960s. The above evidence indicates that the biomass of this stock is unlikely to be recruitment overfished.

Landings in New South Wales in 2013 (93.84 tonnes [t]) were lower than the long-term annual average (152.32 t). Summed across all methods in the Estuarine General Fishery, about 15 113 fisher-days were reported during 2013. This was the lowest annual effort for that fishery on record⁸. The size composition of fish measured during the 2012–13 financial year was similar to previous years, suggesting no large changes to the size frequency of the stock⁸. Although this species is likely to be primarily harvested by the recreational sector in New South Wales, recent estimates of recreational catch or effort are unavailable. The above evidence indicates that the current level of commercial fishing pressure is unlikely to cause this stock to become recruitment overfished, notwithstanding the unknown effects of recreational fishing pressure.

On the basis of the evidence provided above, Dusky Flathead in New South Wales is classified as a sustainable stock.  

Victoria

Most Dusky Flathead caught in Victoria are taken from the Gippsland Lakes. The most recent assessment for Dusky Flathead in the Gippsland Lakes was undertaken in 2011. The assessment indicated that commercial and recreational catch rates for Dusky Flathead are highly variable, but there was no evidence of a long‐term decline. Commercial mesh-net catch rates in 2009–10 were above both the long‐term and the 10‐year averages⁴. The above evidence indicates that the biomass of this stock is unlikely to be recruitment overfished.

Commercial catches of Dusky Flathead dropped from 17 t in 2012 to 6 t in 2013; however, this level of annual catch is still double the size of commercial catches from the early 2000s. The trend in the 5‑year moving average of recreational catch rates is stable⁴. Available recreational monitoring data (2005, 2006, 2009 and 2010) suggest that recreational fishers in the Gippsland Lakes rarely take Dusky Flathead greater than 50 cm total length ⁴. In November 2013, Victoria introduced a slot limit for recreationally caught Dusky Flathead of 30–55 cm. The number of licensed commercial fishers in Victorian waters was reduced by two-thirds between 1986–87 and 2010–11. The majority of the licence removals occurred as a result of voluntary licence buyback schemes conducted in 1999–2000 and 2005–06. The above evidence suggests that the current level of fishing mortality is unlikely to cause the stock to become recruitment overfished.

On the basis of the evidence provided above, Dusky Flathead in Victoria is classified as a sustainable stock.