© 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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Soldierfish / South Australian Cobbler / Happy Moments / Devil Fish

Family Name:	Tetrarogidae
Scientific Name:	Gymnapistes marmoratus (Cuvier, 1829)
Recommended Status in S.A:	Least Concern
Rationale:  The Soldierfish is included here because (i) it is strongly associated with estuaries and nearshore seagrass beds, and may thus be vulnerable to population decline due to habitat impacts in some coastal areas; and (ii) it forms seasonal aggregations (probably for spawning), and this behaviour may increase the vulnerability of Soldierfish to site-specific impacts; (iii) the species is relatively slow growing and long lived (estimated to be about 14 years), and such life history characteristics may increase the vulnerability of Soldierfish to population impacts. Despite these characteristics, the suggested status for Soldierfish is Least Concern, due to the broad geographic range of this species, and its abundance in many parts of the range. Soldierfish may be a suitable indicator species in some areas where seagrass cover has declined, and attempts are made to restore the habitat over time.

Page Contents

Current Conservation Status

no listings known

Distribution

Southern Australia

The Soldierfish is widely distributed across southern Australia, from the central coast of N.S.W. (Sydney) through to southern W.A. (Fremantle area), and including Tasmania (Hutchins and Thompson, 1983; Hutchins and Swainston, 1986; 2001).
Soldierfish is a species of relatively high abundance, including large seasonal aggregations, in shallow seagrass habitats across southern Australia (Hutchins and Swainston, 1986; Poss, in Gomon et al., 1994; Kuiter, 1996a; Jenkins et al., 1997; Edgar, 2000; O’Hara et al., 2002).
The species is considered to be common in Victoria (DPI Victoria, 2003a).
In Tasmania, the species has been recorded from bays, estuaries and harbours around the State (e.g. Grant, 1972; Jordan et al., 1998; Edgar, 1984, 1991, cited by RPDC, 2002).

South Australia

In S.A., the species is commonly known from the Gulfs region and the upper South – East, but has also been recorded in the western part of the State. Examples of locations in South Australia where the species has been recorded include Investigator Group islands in the eastern Great Australian bight; northern, central and southern Spencer Gulf; areas along the metropolitan coast of Gulf St Vincent (e.g. Outer Harbour, Port River - Barker Inlet system, Patawalonga); south-western Gulf St Vincent (e.g. Edithburgh, Port Giles), Kangaroo Island (e.g. American River, and other locations), Encounter Bay, and various parts of the Murray Mouth area near Goolwa (Ward et al., 1986; Hureau, 1991; Anonymous, 1993; Jones et al., 1996; Carrick, 1997; Anonymous, 2001a, cited in Froese and Pauly, 2007; Fairhead et al., 2002a, 2002b; Ye et al., 2002; Higham et al., 2002; photographs by J. Lewis, 2005; Bloomfield and Gillanders, 2005; SARDI, 2006; BMNH specimen no. 1896.6.17.37, cited in Natural History Museum, 2006; Australian Museum records, cited in Australian Museum, 2006h).

Habitat

G. marmoratus is found abundantly in shallow seagrass beds, in coastal bays and estuaries, and also on sandy and silty bottom in deeper water (Hutchins and Swainston, 1986, 2001).
The species has been recorded abundantly in Zostera and Heterozostera seagrass beds, but has also been found in Posidonia seagrass beds, and to a lesser extent in un-vegetated muddy and sandy habitats (Robertson, 1980; McNeill and Bell, 1992; Bell et al., 1992; Jenkins et al., 1997; Jordan et al., 1998; O’Hara et al., 2002; Hyndes et al., 2003; Bloomfield and Gillanders, 2005).
In Tasmania, the species commonly occurs at depths of 20 m or less, over sand or mud bottom with a light Zostera covering (Grant, 1972).
In south-western W.A., G. marmoratus was recorded at a variety of nearshore habitats, including sheltered sites with dense seagrass; moderately wave-exposed sites with sparse seagrass; moderately and fully wave-exposed sandy areas with no seagrass, and moderately wave-exposed areas with macroalgae-covered reefs in the vicinity (Valesini et al., 2004).
In all States in the geographic range, Soldierfish are also associated with estuaries (e.g. Potter et al., 1983; Loneragan and Potter, 1990; Neira et al., 1992; Jones et al., 1996; DPIWE Tasmania, 1999; Pinto, 2001; Kanandjembo et al., 2001; Ye et al., 2002; Higham et al., 2002; Young and Potter, 2003b; DPI Victoria, 2003a). In Victoria, G. marmoratus has also been recorded in mangroves (Hindell and Jenkins, 2004; Smith and Hindell, 2005).

Notes on the Biology and Behaviour

Age and Growth

G. marmoratus grows to around 22cm or 23cm (Hutchins and Swainston, 1986; Australian Museum, 2006h). One of the maximum sizes recorded is 0.112kg (Hutchins and Swainston, 1986), being a specimen taken in Mandurah, W.A., in 1986 (AAA, W.A. Division, 2005).
The species grows slowly, to a maximum age of around 14 years (Grant, 1972, cited in Froese and Pauly, 2007; Edgar, 2000).

Diet

G. marmoratus belongs to a family of bottom-dwelling fishes that are predators of crustaceans and small fishes (Nelson, 1994, cited in Froese and Pauly, 2007). The related species Centropogon australis (from south-eastern Australia) eats mainly crustaceans found in seagrass beds, and the diet of G. marmoratus is similar (Bell et al., 1978).
Grant (1972) found that shrimps and crabs made up a large portion of the diet of smaller G. marmoratus, while larger Soldierfish consumed other fish species as well. Similarly, Robertson and White (1986) recorded mainly crustaceans in the diet of G. marmoratus.
Depth related differences in diet have been noted. For example, in Port Phillip Bay, G. marmoratus at shallow depths are reported to eat 100% crustaceans, whereas Soldierfish at intermediate depths also eat polychaete worms and other benthic fauna, and crustaceans make up about 70% of the diet (Parry et al., 1995, cited by Hart et al., 2004).

Reproduction

According to Grant (1972), age at first maturity is approximately 2 years.
In late winter and early spring, adult Soldierfish leave shallow seagrass beds to congregate in large numbers in deeper water, presumably for spawning (Edgar, 1997, 2000).
Jenkins (1986) recorded the larvae as being abundant in Port Phillip Bay in Victoria during the winter-spring (e.g. August – September) period. In study in Port Phillip Bay, numbers of G. marmoratus larvae were higher in the plankton during rough weather compared with calm weather, suggesting that secondary planktonic dispersal can occur for such species, which normally settle in seagrass (Moran et al., 2003).
Potter et al. (1996, 2000) considered that estuaries are important nursery areas for the juvenile stage of G. marmoratus. In one study in south-western W.A., juveniles of this marine species were almost entirely restricted to the estuarine area adjacent to the bay into which the older Soldierfish recruit (Potter et al., 1996). In south-western W.A., Valesini et al. (2004) recorded juveniles in a variety of nearshore habitat types throughout the year; but in the spring, almost exclusively from sheltered seagrass, supporting the earlier work that indicated the importance of sheltered nursery areas for juvenile Soldierfish.

Other Information

The 13 dorsal spines are venomous (Hutchins and Thompson, 1983; Hopkins et al., 1997).

Fisheries Information

Commercial – Southern Australia

G. marmoratus is listed as part of the bycatch in the Commonwealth-managed Southern and Eastern Scalefish and Shark Fisheries (SESSF) (AFMA, 2002a).
The species is part of the bycatch in a number of trawl fisheries. For example, in the otter trawl sub-fishery of the Commonwealth-managed South East Trawl Fishery (SETF), an Integrated Scientific Monitoring Program (ISMP) reported that in 35 trawl shots, about 127kg of G. marmoratus was discarded (Wayte et al., 2004). In the Danish seine sub-fishery of the SETF, the ISMP reported 376kg of Soldierfish discarded from 71 shots (Wayte et al., 2004).
Soldierfish is a bycatch species in estuarine prawn trawl fisheries in New South Wales (N.S.W. Department of Primary Industries, 2004; Australian Museum, 2006h).
G. marmoratus is also collected in Tasmania for the aquarium industry. The permitted annual catch limit is 1,200 individuals, with a fishing block limit (6 x 6 nautical miles) of 200 individuals (DPIWE Tasmania, 2005b; Australian Government DEH, 2005b). In 2006, specimens were being advertised for sale through a Tasmanian aquarium supply company.
Soldierfish is part of the bycatch in the Victorian eel fishery (DPI Victoria, 2003a).
The species is occasionally taken by netters (Hutchins and Thompson, 1983, 2001).

Commercial – South Australia

In the Spencer Gulf prawn trawl fishery in South Australia, 303 Soldierfish were recorded in the bycatch from 32 trawl tows, in a sampling program during the mid 1990s, which represented between 1% and 2% of the total number of scalefish in the bycatch in those tows (Carrick, 1997; Svane, 2005).
In S.A., during bycatch sampling in the Blue Crab fishery (2002-2003), few specimens were recorded in Spencer Gulf (i.e. 1 in 2002 and 2 in 2003); in Gulf St Vincent, 2 specimens were recorded in 2002, and 18 specimens in 2003, with the reported frequency of capture during the latter period being 0.38% (Svane and Hooper, 2004).

Recreational

The species, which is poisonous, is not usually targeted recreationally. Soldierfish are caught incidentally, and some fishing clubs and associations keep records of the maximum sizes caught.

Vulnerable Characteristics of the Species

The Soldierfish is a benthic species associated with estuaries and shallow marine seagrass beds, and may thus be vulnerable to population decline due to habitat impacts in some coastal areas, in all States in which it occurs.
The species forms seasonal aggregations (probably for spawning), and this behaviour may increase the species’ vulnerability to impacts.
The species is slow-growing and relatively long-lived (e.g. 14 years) (Grant, 1972; Edgar, 2000).

Threatening Processes

The inshore distribution, benthic nature and diet (i.e. crustaceans in seagrass) of G. marmoratus in southern Australia may make some populations susceptible to site-specific impacts in some areas. A small number of studies have specifically mentioned potential impacts of habitat degradation on G. marmoratus: (i) the abundance of G. marmoratus has decreased significantly in Port Phillip Bay since the 1970s, and Hobday et al. (1999, cited by Hart et al., 2004) considered that this may be due to the loss of seagrass in the Geelong Arm of the bay during the 1980s; (ii) in Port Phillip Bay, Neira and Sporcic (2002) considered that the introduction of exotic species, and other changes in the bay that have contributed to habitat decline during the past 25 years, may be responsible for the lower abundance of Gymnapistes marmoratus larvae observed in 1995-96, compared with 1983-84; (iii) estuarine impacts, such as siltation / reduction to flow, may have short-term impacts on populations of this species in the Murray Mouth area of South Australia (Higham et al., 2002).
In South Australia, the Soldierfish has been recorded in a number of areas that have been subject to considerable habitat modification and decline in habitat quality, as is the case in other States in which the species occurs. In S.A., examples of modified habitats include northern Spencer Gulf (see Baker, 2004, for a review of physical and chemical impacts); Gulf St Vincent (for examples of impacts, see Shepherd, 1970; Hart, 1996, 1997; Cheshire et al., 1998; Cheshire and Westphalen, 2000; Fairhead et al., 2002a, 2002b; Baker, 2004; Westphalen et al., 2005), and the Murray Mouth (for examples of impacts, see Edyvane et al., 1996; Higham et al., 2002, Baker, 2004).
There has been little assessment of the effects of fishing on this species; however a recent draft ecological risk assessment report for the South East Trawl Fishery, listed G. marmoratus as being a “medium risk” species, in terms of population impacts from trawling (Wayte et al. 2004).

Research Requirements

For this species, the only risk assessment undertaken on the effects of fishing has been in the Commonwealth-managed South East Trawl Fishery. Given that G. marmoratus is caught in relatively large number in some State-based fisheries (such as the prawn trawl fishery in S.A.), State-level risk assessments of fishing Soldierfish populations in gulfs and estuaries should be undertaken.
The growth rate and maximum age of this fish, which were estimated during the early 1970s (Grant, 1972), should be validated using modern techniques.
Over time, this site-associated species in estuarine and nearshore marine seagrass beds may be a useful indicator species in areas where pollution reduction and efforts to restore ecological health have been undertaken.
In Tasmania, where this Soldierfish is taken for the aquarium industry, an assessment of the populations and the sustainability of this practice should be undertaken.

Management Requirements

Ongoing efforts are required to reduce the bycatch of benthic fish such as Soldierfish in Commonwealth-managed fish trawls, and in State-based prawn trawl fisheries. During the past decade, examples of various developments in the Gulf St Vincent and Spencer Gulf prawn trawl fisheries to reduce bycatch are provided by Carrick (1997), MacDonald (1998), Broadhurst et al. (1999, 2000), PIRSA (2003), and Svane (2004).
Measures to reduce ongoing physical, chemical, biological and ecological degradation of estuaries may be important for populations of estuarine-dependent benthic fish. Measures to restore degraded estuaries are equally significant. It is noted that an Estuaries Policy and Action Plan has recently been developed in South Australia (DEH South Australia, 2005), to address the issues of estuarine degradation and restoration, and it is important that the recommendations in this policy be implemented as far as possible by government, industry and community.  Related to this, ongoing efforts are required to reduce the levels of degrading processes that affect nearshore seagrass beds, and to restore such habitats.  Soldierfish may be a suitable indicator species in some areas where seagrass cover has declined, and attempts are made to restore the habitat over time.
In Tasmania, where Soldierfish is taken for the aquarium industry, an assessment of the populations, and sustainability of this practice, should be undertaken.

Other Information

The species occurs in a number of Marine National Parks (MNPs) in Victoria, such as Port Phillip Heads MNP, Yaringa MNP, French Island MNP, Churchill MNP and Corner Inlet MNP (Plummer et al., 2003).
G. marmoratus has been recorded in the Tinderbox Marine Reserve in Tasmania (G. Edgar, University of Tasmania, pers. comm., 2006).