© Baker, J.L. (2009) Marine Species of Conservation Concern in South Australia Full citation Baker, J.L. (2009) Marine Species of Conservation Concern in South Australia: Volume 1 - Bony and Cartilaginous Fishes. Report for the South Australian Working Group for Marine Species of Conservation Concern. J. Baker (consultant); Science and Conservation Division, and Coast and Marine Conservation branches of S.A. Department for Environment and Heritage (DEH); Marine and Coastal Community Network of S.A. (MCCN), and Threatened Species Network (TSN). Web version published by Reef Watch, South Australia.

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GEMPYLIDAE: GEMFISHES

© Bernard Yau

 
The family Gempylidae contains large, elongate, mackerel-like fishes, mostly found in deep marine waters, particularly in tropical and sub-tropical regions (Gomon, in Gomon et al., 1994; Nakamura and Parin, 1993, cited in Froese and Pauly, 2009). There are few species per genus; 24 species within 16 genera are currently recognised within the family, which includes snake mackerels, escolars and gemfish (Froese and Pauly, 2009).

Gemfishes have fang-like front teeth, a deeply forked tail, rows of small finlets behind the dorsal and anal fins, and very small scales (or no scales at all) (Edgar, 2000). Most gemfish species are active carnivores, preying on fish in offshore waters (Edgar, 2000).

Two distinct Australian stocks are evident (Colgan and Paxton, 1997). Genetic profiles have shown highly significant differences between eastern and southern/western Australian specimens. The boundary between the stocks is at the western end of Bass Strait, with limited mixing off western Tasmania (Colgan and Paxton, 1997).

For fisheries management purposes, the eastern and southern/western populations can be considered completely separate breeding stocks (Colgan and Paxton, 1997). The Eastern stock is not discussed in this report, because it does not occur in South Australian waters. However, it is noted that the eastern stock of Gemfish has been one of the most important trawl fishes in south-eastern Australia, but is currently overfished (Rowling and Makin, 2001; Paxton, 2003; AFFA, 2004a; Larcombe and Begg, 2008), after several decades of target fishing, including large catches of individuals on spawning migrations (the “gemfish run”). Given the severely depleted state of the eastern Gemfish stock during the past two decades, it has been stated that “no guarantee can be given that the stock will recover to former levels, even if the remaining fish are totally protected from exploitation” (Rowling, 1995a,b), and the spawning stock biomass has been significantly reduced. Large quantities of juvenile Gemfish were also being caught into the 2000s, prior to maturity. The conservation status of the depleted eastern stock is detailed in Pogonoski et al. (2002) and Australian Government Department of the Environment and Heritage (2003c), the latter being the nomination received by government to list the Eastern population of Rexea solandri as endangered, under the Environment Protection and Biodiversity Conservation Act, 1999. In both 1999 and 2002-2003, the Humane Society International (HSI) nominated the Eastern stock of Gemfish to be listed under the EPBC Act 1999 as a threatened species. New South Wales Fisheries provided a statement of support for the nomination, because in that State, there has been a significant reduction in the eastern stock. In 2004, the Australian Society of Fish Biology considered the eastern stock of this species to be vulnerable. In 2006, the Fisheries Scientific Committee, established under Part 7A of the New South Wales Fisheries Management Act 1994, proposed to list Rexea solandri as an endangered species in New South Wales, but in 2008, that committee decided not to list the species, based on an abundance survey in 2007. However, the results of the survey may have been the product of a single strong year of recruitment (reported in 2002). New South Wales Department of Primary Industries (2007f) has deemed eastern Gemfish to be recruitment over-fished. At a national level, the Threatened Species Scientific Committee considered that the eastern population of Gemfish met sufficient elements of Criterion 1 (i.e. has undergone, is suspected to have undergone or is likely to undergo in the immediate future a very severe, severe or substantial reduction in numbers) to make it eligible for listing as endangered, but also met the requirements of section 179(6)(b) of the EPBC Act 1999, to be eligible for listing as conservation dependent. The Committee judged that the most appropriate category of listing for Eastern Gemfish was conservation dependent, and accordingly, eastern stock of Gemfish was listed in 2009 as such (Anonymous, 2009). This listing permits the stock to continue to be fished (AFMA, 2009c), despite its heavily depleted status, and qualification for listing as endangered.

Although the eastern stock of Gemfish does not occur in South Australia, the western population of Gemfish has many similar life history traits, and is included below, as a species of conservation concern.

Associated taxa

Gemfish / Common Gemfish (Western Stock) / Hake

Rexea solandri (Cuvier, 1832)