© 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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Minor Gurnard / Cocky Gurnard / Grooved Gurnard and western relative

Family Name:	Triglidae
Scientific Name:	Lepidotrigla modesta Waite, 1899 and Lepidotrigla sp. (undescribed western relative)
Recommended Status:	Both possibly Least Concern in S.A. L. modesta possibly Near Threatened in SE Australia
Rationale:  Despite the broad depth range across the continental shelf, L. modesta and the undescribed western relative are included here because (i) they are site-associated benthic species that are vulnerable to capture in benthic trawls and seines on the continental shelf; (ii) L. modesta is caught and discarded in seemingly large, unregulated quantities in the South East Trawl Fishery (SETF), and is also commonly caught in fish trawls in N.S.W.; (iii) risk assessments in trawl fisheries have shown that L. modesta is at moderate to high risk of population impacts from trawl capture; and (iv) there is little information on distribution and relative abundance of either species over the range (including S.A.), and on the biology, population dynamics and ecology. There is no evidence to date that these species are caught in large quantities in any State-based fishery in S.A., and thus both are listed here as being of Least Concern. Given the large, uncontrolled catches of L. modesta in the Commonwealth-managed SETF, and in fish trawl fisheries in N.S.W., coupled with the lack of information about population sizes, biology, and sustainability of catches, this species may qualify for listing as Near Threatened in south-eastern Australia.

Page Contents

Current Conservation Status

no listings known

Distribution

Southern Australia

L. modesta: The Minor Gurnard occurs from the northern N.S.W. border through to the Victorian / S.A. border (M. Gomon, Museum of Victoria, pers. comm., 2006).  The majority of museum specimens of L. modesta come from N.S.W., Victoria and Tasmania (Australian Museum records, Museum of Victoria records, cited in OZCAM database, 2006).
Lepidotrigla sp. (undescribed): An undescribed western cognate previously thought to be L. modesta occurs from just south of Shark Bay in W.A., through to western South Australia (M. Gomon, Museum of Victoria, pers. comm., 2007).

South Australia

Lepidotrigla sp. (undescribed): There are few published records from S.A., but examples where the western relative of L. modesta has been recorded include deeper continental shelf waters in the Great Australian Bight (Brown and Knuckey, 2002; Museum of Victoria records, cited in OZCAM database, 2007; CSIRO Marine Research data, cited in CSIRO, 2007).

Habitat

L. modesta occurs in continental shelf waters. The reported depth range is between 10m and 200m+ deep (Gomon, in Gomon et al., 1994; Neira et al., 1998), and there are reported to be isolated records from as deep as 308m (CSIRO et al., 2001). In southern Australia, the species is more commonly found within the depth range 50m – 150m (CSIRO et al., 2001).
In the shallow part of the range, L. modesta has been recorded from clear coastal bays, on sand in the vicinity of reefs (Kuiter, 1996a).
In southern W.A., during a 1991-93 study of fish fauna over sandy substrates between 5-35 m depth, the undescribed western relative of L. modesta was recorded mainly at depths greater than 20m (Hyndes et al., 1999).

Notes on the Biology

Growth

L. modesta grows to around 20cm (Kuiter, 1996a) or 22cm (Neira et al., 1998).

Diet and Feeding Behaviour

L. modesta may be nocturnally active (Kuiter, 1996a). Generally, species in the family bury in the substrate during the day, and start hunting for food at dusk (Kuiter, 2000). Species in Triglidae eat small benthic fishes, crustaceans and other invertebrates that live in or on the substrate (Kuiter, 2000). Platell and Potter (1999) recorded amphipods and mysids in the diet. Benthic invertebrates also have been recorded in the diet of L. modesta (Bulman et al., 2001).

Reproduction

Lepidotrigla species have buoyant, pelagic eggs (Neira et al., 1998).

Other Information

Like other gurnards, these species can “walk” along the sea floor using the feelers in front of the enlarged pectoral fins (Hutchins and Swainston, 1986).

Fisheries Information

Commercial

L. modesta is a significant part of the discarded bycatch in the Commonwealth-managed Southern and Eastern Scalefish and Shark Fisheries (SESSF) (AFMA, 2002a). In the otter trawl sub-fishery of the South East Trawl Fishery (SETF), an Integrated Scientific Monitoring Program (ISMP) reported that in 836 trawl shots, about 1kg of L. modesta was retained and 42.9 tonnes were discarded (Wayte et al., 2004), an average of 51kg per trawl shot. In the Danish seine sub-fishery of the SETF, the ISMP reported that in 293 shots, about 18.1 tonnes of this species were discarded (Wayte et al., 2004), which averages 62kg per shot. Additionally, in the Danish seine sub-fishery, the ISMP recorded 9.3t of unspecified Lepidotrigla in 213 shots (an average of 32kg per shot).
L. modesta is a significant part of the bycatch in the ocean fish trawls (shelf sector) in New South Wales, with a frequency of occurrence of 70% across all trawls sampled, with an additional 4% occurrence in the Wreck Bay and Tathra inshore grounds of the ocean fish trawl fishery (N.S.W. Department of Primary Industries, 2004). It is a minor part (4% occurrence) of the bycatch in the deepwater sector of the N.S.W. ocean prawn trawl fishery (N.S.W. DPI, 2004).
The western relative of Minor Gurnard is a minor bycatch species in the Great Australian Bight Trawl Fishery, with only 4.3kg (in 4 shots) recorded and discarded during a scientific monitoring program in 2001 - 2002 (Brown and Knuckey, 2002).

Recreational

Minor Gurnard is occasionally taken recreationally (e.g. gill-netting in Tasmania, Lyle et al., 2000).
Gurnards in general are taken by some recreational fishers in southern Australia, including S.A. (see statistics from Henry and Lyle, 2003, cited above), but species-specific data are not available.

Vulnerable Characteristics of the Species, and Threatening Processes

Both species occur in sand habitats, and are vulnerable to capture in trawlers and seine nets that operate on the continental shelf. For example, L. modesta is caught in apparently large quantities in the South East Trawl Fishery.
In a draft ecological risk assessment report for the South East Trawl Fishery (Wayte et al. 2004), 4 “productivity attributes” and 6 “susceptibility attributes” were used to classify L. modesta as being a “medium risk” species in terms of potential population impacts from trawling.
L. modesta has been listed as one of the bycatch species in the N.S.W. Ocean Trawl Fishery that has a “high” fishery impact profile (New South Wales Department of Primary Industries, 2004). A study in N.S.W. reported that the species suffers barotrauma when hauled in trawls; has moderate “resilience”, but a low probability of survival when caught, and L. modesta was classified overall as a “high risk” species in terms of population impacts from trawl fishing (NSW DPI, 2004).

Research Requirements

There is little information on the distribution and relative abundance over the range, and on the biology, population dynamics and ecology of these species.
There are few published records of the Minor Gurnard and the western relative in South Australia. Benthic fish surveys are required to better determine the distribution and relative abundance of these species within S.A.

Management Requirements

In south-eastern Australia, measures are required to reduce the large bycatch of L. modesta in fish trawl fisheries over the continental shelf, in both State and Commonwealth waters.
Recreational catch limits should be introduced for gurnard species.