© 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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Southern Hulafish / Blotch-tailed Trachinops / Blotched-tailed Trachinops

Family Name:	Plesiopidae
Scientific Name:	Trachinops caudimaculatus McCoy, 1890
Recommended Status in S.A:	Data Deficient
Rationale:  Southern Hulafish is included here because (i) it apparently has a limited distribution in S.A., with most records coming from the western part of the State; (ii) species of Trachinops appear to be territorial; they are strongly associated with reefs and other structures in shallow nearshore waters, and they reproduce at localised scales, having benthic eggs that are guarded; these characteristics can make populations vulnerable to localised impacts; (iii) research in Tasmania has shown that Southern Hulafish populations are susceptible to large fluctuations in abundance over time, possibly associated with oceanographic climate and availability of planktonic prey; therefore, over the long term, global warming could influence fluctuations in Hulafish populations in some areas; (iv) research on a related hulafish species in eastern Australia has shown that Trachinops species are susceptible to population impacts from nearshore pollutants, such as effluent discharge; (v) the species is taken in Tasmania for the aquarium trade, and fishes with such value may prompt illegal trade (or personal collecting) in other parts of southern Australia, where no specific fishery exists; (vi) little information exists about the biology and population dynamics of this species; and (vii) no surveys have been undertaken to estimate the full distribution and relative abundance of Southern Hulafish in the South Australian part of the range.

Page Contents

Current Conservation Status

No listings known

Distribution

Southern Australia

Southern Hulafish has a south-eastern Australian (Maugean) distribution, restricted to Victoria, Tasmania and South Australia (Hutchins and Swainston, 1986, 2001; Kuiter, 1996a).
Southern Hulafish is common in Tasmania, where large schools are encountered (Hutchins and Swainston, 1986; Kuiter, 1996a), but large, cyclical fluctuations in abundance are evident (Barrett et al., in prep., cited by G. Edgar, University of Tasmania, pers. comm., 2006). The specie is also common on nearshore reefs in parts of Victoria, such as Port Phillip Bay (Edmunds and Hart, 2003; Edmunds et al., 2004). At one site in northern Port Phillip Bay, densities of 2,200 hulafish per 2000m² have been recorded (Hart et al., 2003).

South Australia

There are few records from South Australia compared with those for the related species, T. noarlungae, and published records of this species are mainly from the western part of South Australia.
Examples of locations in S.A. where T. caudimaculatus has been recorded include Nuyts Archipelago and the Investigator Group islands, in the eastern Great Australian Bight; western Eyre Peninsula (e.g. Pt Westall); southern Eyre Peninsula (e.g. Perforated I.); and northern Kangaroo Island (e.g. Cape Cassini) (Kuiter, 1983; K. Branden and S. Shepherd, unpubl. data, 1987; S. Shepherd and A. Brown, unpubl. data, 2002; Shepherd and Brook, 2002b; S. Shepherd, unpubl. data, 2003). In Gulf St Vincent, there are unverified (and unverifiable) records by Reef Watch, from Noarlunga Reef, Aldinga, Second Valley and Rapid Bay (Reef Watch data, 1999- 2004).

Habitat

Found on sheltered and moderately exposed reefs (Edgar, 2000), including rocky estuaries, and deeper reefs further offshore (Kuiter, 1996a).
In northern Port Phillip Bay in Victoria, the species has been recorded sheltering in depressions between small reef outcrops (Hart et al., 2003). Southern Hulafish has also been recorded schooling over Ecklonia kelp on shallow reefs, and also over more sheltered reefs that are devoid of large canopy species, and covered with smaller green (e.g. Caulerpa) and red macroalgae (e.g. Edmunds et al., 2004). At the entrance to Port Phillip Bay, T. caudimaculatus has been observed deeper than 20m, in the vicinity of reef “walls” and associated reef structures dominated by mixed sponges and other invertebrates (e.g. Elias et al., 2004).
In addition to structure in natural reefs (e.g. “drop-offs” and “reef walls”), Southern Hulafish is also associated with artificial structures such as piers / jetties (Museum of Victoria records), rock walls and forts (Edmunds et al., 2003, 2004) and breakwaters (Museum of Victoria records, cited in OZCAM database, 2006).
T. caudimaculatus is also reported to be one of the common inhabitants of kelp forests in Tasmania (uncited reference, in Edyvane, 2003).
Reported depth range is about 1m – 35m (Edgar, 2000).

Notes on the Biology and Behaviour

Growth

Southern Hulafish grows to at least 10cm (Hutchins and Swainston, 1986, 2001; Edgar, 2000), possibly 15cm (Kuiter, in Gomon et al., 1994, cited in Froese and Pauly, 2006; Kuiter, 1996a).

Reproduction

Members of Trachinops lay benthic eggs which have anchor-shaped hooks (Mooi, 1990).
The eggs of T. caudimaculatus are tightly bound together and deposited in a protected position (such as a rock crevice) on the substratum.
Male Trachinops are responsible for guarding eggs. For example, the male of the eastern Australian species T. taeniatus has been observed wrapping its long body around the brood, to guard the eggs.

Diet and Feeding Behaviour

T. caudimaculatus is planktivorous (Kuiter, 1996a; Shepherd and Brook, 2002b), and darts around in circles to capture prey (Edmunds et al., 2004). Although the species feeds on zooplankton in the water column, it prefers to feed beside rock crevices, into which it darts when threatened (Edmunds et al., 2004).

Other Information

The species forms small to large schools (Hutchins and Swainston, 1986, 2001).

Fisheries and Trade Information

Commercial

In Tasmania, under the Tasmanian Fisheries (Scalefish) Rules 2004, Regulation 100, there is a commercial fishing possession limitation of a maximum of 3 T. caudimaculatus per licence holder per day, due to the development of a separate aquarium trade (see below).
T. caudimaculatus is caught in Tasmania for sale in the international aquarium trade.  The permitted annual catch limit is 1000 individuals, with a fishing block limit (6 x 6 nautical miles) of 100 individuals (DPIWE Tasmania, 2005b; Australian Government DEH, 2005b).
The species is promoted in the aquarium trade as a “companion species” for tanks with seahorses, because T. caudimaculatus feeds easily and non-aggressively on dried, frozen or live food.

Vulnerable Characteristics of the Species

Hulafish reproduce at localised scales and have benthic eggs, a life history characteristic that increases their vulnerability to site-specific impacts.
Hulafish are site-associated on shallow coastal reefs, over a narrow depth range, which increases the vulnerability of populations to localised impacts.
In Tasmania, research in reserve and non-reserve areas indicates that Southern Hulafish populations show pronounced cyclic variability over the long term, possibly associated with oceanographic climate and availability of planktonic prey (Barrett et al., in prep., cited by G. Edgar, University of Tasmania, pers. comm., 2006). For example, populations displayed a 10-fold increase at both reserve and reference locations between 1992 and 2002 (Barrett et al., in prep.).
Research on the related eastern Australian hulafish species T. taeniatus has shown that hulafish populations may be susceptible to the impacts of sewage effluent discharge. Various studies have reported lower abundance of hulafish (Smith and Suthers, 1999; Smith et al., 1999), smaller body size, and greater number of smaller eggs in hulafish at sewage-affected sites, compared with those in control areas (Smith and Suthers, 1999). Hulafish can take up sewage effluent into the muscle. Gaston et al. (2004) reported that the muscle of T. taeniatus hulafish from near some outfall sites was significantly enriched by secondary and tertiary treated effluent (compared with control sites), and estimated that 30-50% of the ¹⁵N nitrogen in the hulafish may be sewage-derived.
South Australia is at the edge of the species range, and this south-eastern Australian species appears to have a limited geographic distribution in S.A.

Threatening Processes

The main threats to this species may be habitat degradation in some inshore areas (see above, on effluent discharge); and (in some areas) collection for the aquarium trade.
Over the long term, the influence of global warming on oceanographic conditions may have implications for Hulafish populations in some areas.

Research Requirements

More information is required on the distribution and relative abundance of this species, particularly in South Australia, which is at the edge of the species range.
Very little is known of the biology and population dynamics (especially longevity, and reproduction) and ecology of this species.

Management Requirements

Given that research in eastern Australia has shown that hulafish populations are susceptible to population impacts from effluent discharge, continuing efforts to reduce (and eventually eliminate) effluent discharges into nearshore waters should be made, particularly in the gulfs region of S.A., major parts of which are significantly affected by such pollutants.
Reef fish species taken in all southern States for the aquarium trade should be documented over space and time, and sustainability assessments should be undertaken. The potential for illegal collecting of this species should also be monitored and prevented.

Other Information

In Victoria, the species occurs in a number of the Marine National Parks (MNPs) and Marine Sanctuaries, such as Wilsons Promontory (Edmunds et al., 2000, 2003), Gabo I., sanctuaries at Ricketts Point (Jenkins et al., 1996, cited by Plummer et al., 2003; Dedrick, 2004), Jawbone (where very high densities have been recorded – see Hart et al., 2003), and Point Cooke (Edmunds et al., 2004); Point Addis MNP, and various sites in Port Phillip Heads MNP (including South Channel Fort and Popes Eye, the latter of which has been protected from fishing since 1972, and where Southern Hulafish is numerically dominant) (Plummer et al., 2003; Edmunds et al., 2003).
Southern Hulafish occurs in all marine reserves in Tasmania, including Maria Island and Ninepin Point (Parks and Wildlife Service, 2004, 2006), and also in a number of areas in northern Tasmania that have been proposed as marine reserves, with high abundances at some sites (Barrett and Wilcox, 2001).
Southern Hulafish is one of the species monitored by divers in the Reef Watch programs in South Australia and Victoria.
Estimating abundance of hulafish is difficult, given the schooling nature of these species, and the high variability in abundance over space and time (e.g. Edgar et al., 2002).