Sustainability of popular estuary stocks MELBOURNE
Ross Winstanley
During 2019, teams of fisheries scientists around the country conducted the fifth in a series of assessments of major Australian fish stocks. Among those covered in the Status of Australian Fish Stocks 2020 report were species taken by commercial and recreational fishers in two or more states. These included assessments of popular inshore and estuary species: • Luderick Girella tricuspidata • Mulloway Argyrosomus japonicus • Southern Garfish Hyporhamphus melanochir • Yelloweye Mullet Aldrichetta forsteri These four species are among a large range of species
Australian is sustainable. Luderick are taken by state-managed fisheries, and are assessed at that level. QUEENSLAND Commercial catches are confined to southern latitudes where they have fallen from an average of 12 tonnes annually, to four tonnes in 2019. While the lack of data on recreational catches makes classification difficult, there are no concerns about the stock in Queensland waters. NEW SOUTH WALES Successive periods of fishing effort reduction have led to commercial catches falling from the 1989 peak of nearly 800 tonnes, to under 400 tonnes in 2004, and ‘stabilising’ at around the 2019 level, 268 tonnes. Most of the catch comes from the estuaries and is taken by gillnets and haul seines. The recreational catch was estimated at about 50,000
and declined from 41 tonnes in 2007, to three tonnes in 2019. The recreational catch is unknown. Because of difficulties in interpreting catch rate trends, it is not possible to classify the stock status in Victoria. It is doubtful that fishing pressure had significant or lasting impacts on the adult stock. TASMANIA With luderick being a low-level byproduct of net fishing, Tasmania’s negligible commercial and recreational catches suggest that neither stock size nor spawning success have suffered from fishing. Across the four eastern states, with 97% of the combined commercial and recreational catches taken in NSW, all the evidence indicates that, at current levels of fishing, this stock is sustainable. MULLOWAY Mulloway occur in
Luderick have a strong following among anglers in the eastern states. Photo courtesy of Geoff Wilson. taken in inshore, bay and inlet waters around southern Australia. Several other species (eg. snapper) and species groups (eg. bream, trevally, and whiting) also taken in these waters, have been described in previous articles. A number of others are of more localised interest, including eastern sea garfish, greenback flounder, and sea mullet. Details for many of these and other species are available at https://www.fish. gov.au/reports LUDERICK Occurring in estuaries and shallow coastal waters, luderick range from southern Queensland, around to South Australia, including northern Tasmania. Tagging studies show that they can travel between estuaries via coastal waters. While the stock structure is unknown, luderick are believed to belong to a single stock. Fishery statistics show that, overall, the stock off eastern 50
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fish or 30 tonnes in 2017/18, down from about 100,000 fish in 2013/14, during a period of high abundance. Because of the combination of recreational catch limits, reduced commercial fishing pressure, and their high level of post-release survival, the NSW part of the stock is unlikely to face reduced spawning success. VICTORIA Since the assessments shown in the SAFS 2020 report, commercial net fishing has ceased in the Gippsland Lakes where luderick were a by-product in the black bream fishery. Commercial net fishing ceased in Port Phillip Bay in March 2022. As a result, commercial landings of luderick in Victoria are now reduced to by-catch in the one remaining estuary net fishery, in Corner Inlet. In the previous 20 years, Victoria’s main luderick catches came from the Gippsland Lakes,
sub-tropical and temperate coastal and estuary waters in every mainland state. Based on separate assessments of the fisheries in each state, the status of the mulloway stock is sustainable in WA and SA, depleted in NSW and undefined in Queensland. Queensland Recreational fishers account for most of the mulloway catch from Queensland inshore and inlet waters. The 2013/14 catch was estimated to be 98 tonnes, while the state-wide commercial catch was nine tonnes in 2019. New South Wales After peaking at 400 tonnes in the mid-70s, the commercial estuary (net) and coastal (line) catches of mulloway have been less than 100 tonnes since the mid-90s; the 2019 catch was 48 tonnes. In 2017/18, the estimated recreational catch was 90 tonnes, compared to the commercial catch of 72
Mulloway are the largest popular fish in inshore and estuary waters around Australia. Photo courtesy of Geoff Wilson. tonnes in that year. With the commercial fishery based largely on juveniles, and average sizes declining, remedial action was taken in 2013. To restore the heavily-fished stock, these measures included an increase in the minimum size, to 70 cm (the average length at maturity for females), and tighter catch limits for both sectors. Imposing these measures is expected to reduce fishing pressure sufficiently to “allow the stock to recover from its recruitment impaired state”. The available evidence points to mulloway in NSW waters being a depleted stock. South Australia SA’s 2018/19 commercial catch, 117 tonnes, was the third highest ever recorded there. Most (93%) was taken from the Lakes and Coorong fishery which accounts for most of the landings each year. The state’s recreational catch was estimated at 60 tonnes in 2013/14. In the Coorong, the presence of 2-8 year old juveniles in 2019/20 reflected years of successful recruitment, with mulloway spawned in 2015/16 and 2016/17 the most abundant. The lack of older fish is attributed to their movement into adjacent coastal waters, plus the effects of fishing. In 2019/20, mulloway sampled from commercial and recreational catches in coastal waters, ranged in age from five to 24 years, although the species can live to 41 years in SA waters. The lack of older fish was attributed to the impacts of the Millennium Drought on recruitment, and on the effects of fishing. On the basis of the recent evidence relating to stock size, recruitment and fishing pressure, mulloway in SA waters are classified as a sustainable stock.
WESTERN AUSTRALIA Over the past decade, about 70-80% of WA’s annual mulloway catch has been taken by commercial fishers. Reductions in commercial fishing effort in the West Coast and Gascoyne demersal fisheries have seen catches decrease, to settle at 11-28 tonnes since 2007/08; the state-wide catch totalled 13 tonnes in 2019. Boat-based recreational and charter catches have remained low, at <10 tonnes annually, coming mainly from the same regions. In 2017/18, these combined catches totalled four tonnes. The available evidence indicates that the stock is “unlikely to be depleted” or “recruitment impaired”. Hence, mulloway in WA are classified as a sustainable stock. SOUTHERN GARFISH Ranging between Lancelin, WA, to Eden, NSW, of the 10 recognised temperate garfish stocks, six are rated as sustainable, two as depleted and two as recovering. Victoria Past estimates of the combined recreational
catch of ‘garfish species’ in Victoria were 25 tonnes in 2000-01 and 21 tonnes in 2005/06. However, there are no recent or specific estimates of recreational catches of southern garfish. The recent closures of commercial net fishing in Port Phillip Bay and the Gippsland Lakes leave Corner Inlet as the last significant commercial fishery for garfish in the State. In 2020/21, all but one of the 33 tonnes of southern garfish reported statewide, were taken in Corner Inlet. They are taken mainly by seine nets, with some also taken in gillnets. With recent catch rates stable, and recruitment apparently healthy, and major bay/inlet fisheries closed, all indications point to southern garfish in Victorian waters as a sustainable stock. Tasmania Following a sharp decline in commercial catches, a seasonal closure was introduced in 2009 to protect spawning fish. By 2012, increased numbers of size classes and of larger fish indicated a stock recovery, with catches totalling 40-60 tonnes. However, catches
Garfish are a popular on light gear in bays and inlets.
