Sea Mullet Mugil cephalus

Eastern Australian biological stock

The cross-jurisdictional eastern Australian biological stock has components in New South Wales and Queensland. Each jurisdiction assesses the part of the biological stock that occurs in its waters. The status presented here for the entire biological stock has been established using evidence from both jurisdictions.

The New South Wales component of the eastern Australian biological stock is assessed annually in terms of landings and catch rates in both the estuary and ocean fisheries⁴. The annual spawning run fishery on ocean beaches is assessed in terms of fish sizes and ages in landings. Commercial median catch rates have remained stable in the estuary fishery (kilograms per day of mesh netting) and increased slightly in the ocean fishery (kilograms per day of beach hauling) since the early 1980s. The size compositions of fish in ocean landings have remained stable, while the age composition of fish in this fishery is generally between 2 and 5 years, with some variations in year-class strength. The above evidence indicates that the biomass of this part of the stock is unlikely to be recruitment overfished.

Landings in New South Wales in 2013 (2133 tonnes [t]) were well below the long-term annual average (around 3000 t). The reported number of fisher-days in the ocean fishery in 2013 was at a historical low of approximately 650 days. Typical length-frequency compositions were found in landings in 2013. Age compositions in 2011 (the most recent year analysed for age compositions) suggest no large changes in the stock, with most fish being 3–5 years of age. The above evidence indicates that the current level of fishing pressure is unlikely to cause this part of the stock to become recruitment overfished.

The Queensland component of the eastern Australian biological stock has a long history of stable commercial landings. In 2013, 2109 t was reported landed, which is above the long-term average of around 2000 t. Length-frequency information from routine monitoring shows stable distributions of fish sizes harvested by the Queensland fishery. Age-frequency information shows that fish from 3 to 5 years of age dominate catches, but older fish are present. Recruitment has been consistent, with evidence of recent strong year-classes. The above evidence indicates that the biomass of the Queensland component of this stock is unlikely to be recruitment overfished.

Nominal effort in the Queensland component of the fishery has been stable at around 9000 days for the past 5 years, and the number of fishers reporting mullet (unspecified) catch has decreased from 319 fishers in 2009 to 285 fishers in 2013. This decline is expected to continue with planned net licence buy-backs. Length-frequency information shows stable patterns, and catch is well above minimum legal size. Age-frequency information shows continued recruitment to the fishery and evidence of strong year-classes. Estimates of fishing mortality are high compared with estimates of natural mortality, but show a stable trend in combination with consistent catches. The above evidence indicates that the current level of fishing pressure is unlikely to cause the Queensland component of the biological stock to become recruitment overfished.

On the basis of the evidence provided above, the entire biological stock is classified as a sustainable stock.  

Western Australian biological stock

Sea Mullet occurs in all coastal regions of Western Australia, but commercial targeting of the species is mainly restricted to waters from Shark Bay southwards. Sea Mullet is managed separately in the four Western Australian bioregions, although the level of connectivity between the different populations is unknown⁵. The total catch of Sea Mullet in Western Australia has declined since the 1990s, as a consequence of commercial effort reductions in coastal and estuarine areas, attributable to licence buy-backs and spatial closures. The above evidence indicates that the current level of fishing pressure is unlikely to cause the stock to become recruitment overfished.

The assessment for Sea Mullet is based on trends in catches and catch rates in the three main fisheries (Shark Bay Beach Seine and Mesh Net Managed Fishery, South Coast Estuarine Managed Fishery, and West Coast Estuarine [Interim] Managed Fishery) that capture around 80 per cent of the total commercial catch. Catch rates in these fisheries were relatively stable over the period 1980 to 2000, and have increased since 2000. These trends suggest long-term stability in Sea Mullet abundance in each bioregion, with a slight increase in recent years. The above evidence indicates that the biomass of this stock is unlikely to be recruitment overfished.

On the basis of the evidence provided above, the biological stock is classified as a sustainable stock.