Mulloway Argyrosomus japonicus

Western Australia

In Western Australia, commercial catches have steadily declined from around 60 tonnes (t) in 2002 to 12 t in 2013⁷. This progressive decline in catch is likely to be related to reductions in fishing effort resulting from changes during that period to the management of some fisheries—for example, the West Coast Demersal Scalefish (Interim) Managed Fishery and Gascoyne Demersal Scalefish Managed Fishery. The lack of biological information and time series of catch-and-effort or catch-rate data for Mulloway in Western Australia limits our understanding of recruitment patterns that could otherwise identify a trend of declining or increasing biomass. As such, there is insufficient information available to confidently classify status in Western Australia.

On the basis of the evidence provided above, Mulloway in Western Australia is classified as an undefined stock.  

Lakes and Coorong Fishery (South Australia) management unit

The Lakes and Coorong Fishery management unit has traditionally been the most important of the South Australian fisheries for Mulloway, accounting for an average of around 91 per cent of the state’s total catch since 2000. From 2003 to 2011, catches of Mulloway by the Lakes and Coorong Fishery were relatively low (less than 45 t per year), reflecting low levels of targeted effort and low catch per unit effort (CPUE)—an available estimate of relative abundance for Mulloway in the Coorong estuary⁸. Since that period, catch has increased sharply, to around 115 t in 2013, and mean annual CPUE has increased to historically high levels. Age-structure analysis revealed that the recent high catches and catch rates were due mainly to the recruitment of a large biomass of juvenile (3–6‑year old) fish to the fishery (J Earl, South Australian Research and Development Institute, personal communication). The information provided above suggests that the biomass of Mulloway harvested by the Lakes and Coorong Fishery is unlikely to be recruitment overfished. Furthermore, the current level of fishing pressure is unlikely to cause the stock to become recruitment overfished.

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

Marine Scalefish Fishery (South Australia) management unit

The Marine Scalefish Fishery (South Australia) management unit has traditionally provided much lower catches than the Lakes and Coorong Fishery (South Australia). Catches were historically low through the mid- to late 2000s, as a result of historically low targeted fishing effort. However, since the early 1990s, commercial CPUE has followed an increasing trend, indicating a possible gradual increase in fishable biomass⁸. The lack of age data for Mulloway harvested by the Marine Scalefish Fishery limits our understanding of recruitment patterns that could otherwise confirm inform trends in biomass in this management unit. As such, there is insufficient information available to confidently classify the status of this management unit.

On the basis of the evidence provided above, the management unit is classified as an undefined stock.  

Victoria

Commercial catches in Victoria have mostly been landed from Port Phillip Bay, and from Western Port until Western Port was closed to commercial net fishing in 2008. Most of the catch was taken using mesh nets and haul seines. Over the past 10 years, annual catch by the commercial sector has been less than 0.6 t.

Recreational fishing for Mulloway has become increasingly popular over the past few years. The fishery is distributed throughout Victorian estuaries, rivers and nearby beaches. No assessment or review of the data available for this species has been conducted in recent years. The lack of biological information and time series of catch-and-effort or catch-rate data for Mulloway in Victoria limits our understanding of recruitment patterns and our ability to make a meaningful assessment. As such, there is insufficient information available to confidently classify the status of this stock.

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

New South Wales

Commercial landings in New South Wales steadily declined from almost 400 t in the mid-1970s to 37 t in 2008–09. Commercial landings have been less than 100 t per year since the mid-1990s. In 2013, the total commercial catch for New South Wales was 65 t. Nominal commercial catch rates for Mulloway have declined during the past 20 years in both the ocean and estuarine fisheries (unpublished data from New South Wales Department of Primary Industries). The average lengths of Mulloway landed by the commercial fishery have declined since the mid-1990s^3,9. The age composition of fish in commercial landings in the early 2000s was indicative of a heavily fished stock (98 per cent of catch was less than 5 years old)^3,9. Fishing mortality is estimated to be greater than natural mortality^3,9. The spawning potential ratio for Mulloway was estimated to be between 4 and 14 per cent^3,10, which is below the threshold reference point of 25 per cent. This indicates that there may be a high risk of recruitment failure^11,12. The above evidence indicates that the stock is likely to be recruitment overfished.

In 2013, a recovery program for Mulloway was introduced in New South Wales to arrest the decline in commercial and recreational Mulloway fisheries. Management changes to the recreational Mulloway fishery consisted of an increase in legal minimum size from 45 to 70 cm (the approximate size-at-maturity for female Mulloway in New South Wales^3,9,13) and a 40 per cent reduction in the bag limit. Management changes to the commercial Mulloway fishery consisted of the above increase in legal minimum size (with bycatch limits for the estuarine mesh net fishery) and a 500 kg trip limit for the beach-hauling net sector. The above evidence indicates that current fishing pressure is constrained by management to a level that should allow the stock to recover from its recruitment overfished state. However, measurable improvements are yet to be detected.

On the basis of the information provided above, Mulloway in New South Wales is classified as an overfished stock.  

Queensland

Mulloway are predominantly taken by recreational anglers in Queensland, with an estimated 133 t caught in 2010–11¹⁴. The East Coast Inshore Fin Fish Fishery (Queensland) contributes minimal quantities (5‑year average of 2 t) to the overall Queensland harvest of Mulloway. The legal size limit (75 cm total length) protects a proportion of spawning fish from fishing, while a conservative recreational bag limit (two fish) reduces fishing pressure on the stock. There are anecdotal reports of incidental mortality of Mulloway below the legal minimum size from commercial net fisheries; however, this has not been quantified. Insufficient information is available to confidently classify the status of this stock.

On the basis of the evidence provided above, Mulloway in Queensland is classified as an undefined stock.