Sustainability of popular morwong 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 coastal and offshore morwong species: • Banded morwong, Cheilodactylus spectabilis • Blue morwong, Nemadactylus valenciennesi • Grey morwong, Nemadactylus douglasii • Jackass morwong, Nemadactylus macropterus These and other morwongs are taken by a number of methods within the wide range used by recreational and commercial fishers: spearfishing, hooking, trapping, gill netting and trawling. To counter the paucity of information on these species in the SAFS report, additional information on recreational catches has been taken from state surveys of recreational and charter fishing. BANDED MORWONG Growing to almost 60cm, banded morwong are a popular target species on open coastal reefs for spearfishers off southern NSW and Victoria. Previously regarded by the commercial fishery as a discard or by-catch species, targeted gillnetting for the
Banded morwong are popular among spearos in NSW and Victoria. Photo courtesy of Jordan Hill. live fish market developed in Tasmania and Victoria during the 1990s. While there is no information on stock structure, the SAFS assessment considered the Victorian and Tasmanian fisheries to be based on distinct populations. Tasmanian fishery Banded morwong is a minor species among Tasmania’s recreational fishers. This was reflected in the 2017/18 survey which found the recreational catch to total two tonnes. Until the lucrative livefish market began during
the 1990s, this species was disrespectfully referred to as ‘carp’. After rapidly peaking at 145 tonnes in 1993, the new small-scale commercial fishery declined to 35 tonnes in 1999. Introduced in 2008, a Total Allowable Catch has been stepped down, to 39 tonnes in 2012, then to 31 tonnes in 2018. While banded morwong have been aged to 96 years, fish older than 20 years have become rare. At the same time, the proportion of fish younger than eight years in the population has increased and shown signs of faster growth and earlier
maturity. A slot size (36-46cm) and spawning closure provide additional protection to help stabilise the population and its spawning potential. These conservative measures contribute to the classification of banded morwong in the Tasmanian ‘management unit’ as a “sustainable stock”. While not shown in the SAFS report, Victoria’s commercial fishery is closely managed under measures including a TAC, seasonal and spatial closures, and a size limit. Banded morwong in the Victorian management unit are classified as “undefined”. BLUE MORWONG OR QUEEN SNAPPER Although it occurs in coastal waters, from NSW to southern WA, the stock structure of blue morwong is unknown. Consequently, the stock has been assessed at the jurisdictional level. The SAFS report states, “the species is not a major component of recreational landings”. This is an understatement as only WA has a recorded combined recreational plus charter catch: 16 tonnes in 2017/18. At 44 tonnes in 2018, WA is also
Regarded as unlikely to be targeted by recreational fishers, there are no annual estimates of blue morwong catches. South Australia Blue morwong are not considered a “major component of recreational landings” and commercial catches have averaged 1.4 tonnes in the past 20 years. Hence, fishing has little impact on the stock. SA’s 2013/14 recreational fishing survey found that 2705 blue morwong, weighing about three tonnes, were landed by recreational fishers. In the same year the commercial catch was one tonne. Western Australia In contrast to the other southern states, both recreational and commercial fishing regularly report catches of blue morwong, from the lower west coast and the south coast. Taken by hooking and spearfishing, the recreational catch in 2017/18 was more than 4000 fish, averaging 3kg and totalling 14 tonnes, while the commercial catch in 2018/19 was 45 tonnes, taken mainly by gillnetting. Commonwealth Blue morwong occur as an incidental catch in
spearfishers, this is a popular species and is widely referred to as blue morwong. In the absence of information on their stock structure, they have been assessed as a single East Coast stock. With few caught off Queensland, and few records of catches off Victoria and Tasmania, the major fisheries are by NSW recreational and commercial fishers and by Commonwealth-managed commercial fisheries. Total annual catches have declined from 90 tonnes in 2010 to 40 tonnes in 2018. Queensland The few grey morwong landed commercially as incidental catches off southern Queensland are recorded with other morwong species in combined annual totals of less than one tonne. Recreational catch numbers are equally obscure. New South Wales Records show that commercial catches of grey morwong have declined since the 1970s. The shorter series of recreational catch records show a fall from 156 tonnes in 2000/01, to 22 tonnes in 2017/18. The sizes of fish landed have “declined
Dusky morwong, butterfish or strongfish are the largest morwong species. Photo courtesy of Jordan Hill.
Blue morwong or queen snapper are popular with offshore anglers in WA. Photo courtesy of Lachy Warren. 52
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the only state where average annual commercial catches exceed one tonne. New South Wales While well regarded as a table fish, as blue morwong are not targeted by recreational or commercial fishers in NSW, catches are consistently low (one tonne in 2018/19). Hence, the impacts of fishing on the stock are considered to be small. Tasmania Annual commercial catches total less than one tonne and occur as a small by-catch from gillnetting.
Commonwealth-managed hook, gillnet and trawl fisheries, with a combined catch of 21 tonnes in 2018. Based on the scant available information overall, blue morwong stocks “are classified as sustainable in WA, negligible in NSW and SA, and undefined with limited data in TAS and by the Commonwealth.” GREY MORWONG Grey or ‘rubber lip’ morwong occur on the continental shelf, from southern Queensland to Tasmania’s east coast. Among
substantially” and there is no sign of recovery of the species off NSW. The estimated numbers retained by recreational fishers fell from 43,000 in 2013/14 to 27,000 in 2017/18 (including 4000 from estuaries). Despite the continuing decline, grey morwong still feature prominently in coastal recreational catches. A 2017/18 study showed that, with 14,000 retained, this species is ranked third to bluespotted flathead and snapper among catches from the charter fishery, particularly off the central to
