© 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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Australian Burrfish / Deepwater Burrfish

Family Name:	Diodontidae
Scientific Name:	Allomycterus pilatus Whitley, 1931
Recommended Status in S.A:	Data Deficient (requiring fisheries impact assessment)
Rationale:  Although the Australian Burrfish has a broad geographic range across southern Australia, it is included here because the species (i) aggregates in continental shelf waters, which can increase its vulnerability to threatening processes; (ii) is highly vulnerable to capture in trawls (and other nets) in both State and Commonwealth waters across southern Australia, and is caught in some fisheries (such as the South East Trawl Fishery) in seemingly very large numbers; (iii) suffers barotrauma when caught in trawls, and therefore survival rate of discarded specimens is likely to be low, and trawling bycatch studies have reported that the Australian Burrfish is vulnerable to population impacts from trawl capture; and (iv) there is inadequate information on the relative abundance and population dynamics (including annual recruitment strength) of this species, including populations in South Australian waters, hence it is not possible to determine to what extent capture in Commonwealth- and State-managed fisheries may impact populations.

Page Contents

Current Conservation Status

No listings known

Distribution

Southern Australia

The Australian Burrfish ranges across southern Australia, from central N.S.W. through to southern W.A., including Tasmania (Hutchins and Swainston, 1986). It is also known from some seamounts on the Norfolk Ridge, Tasman Sea (Australian Museum, 2005i).

South Australia

Examples of locations in S.A. in which specimens reported to be this species have been recorded include deeper continental shelf waters in the western, central and eastern Great Australian Bight (from where most of the S.A. records of this species have come); Spencer Gulf (e.g. north-eastern and eastern), Investigator Strait, and western Kangaroo Island (Australian Anglers Association, 2004; Australian Museum, 2005i; Australian Museum records; South Australian Museum record, cited in OZCAM database, 2007; CSIRO Marine Research data, cited in CSIRO, 2007).

Habitat

Australian Burrfish is a demersal species which has a broad depth range, from as shallow as 5m in estuaries and off beaches, to at least 320m in offshore waters (Australian Museum, 2005i). CSIRO et al. (2001) reported that the species is most often found within the depth range 150m – 250m, but that specimens have been found as deep as 450m.
Given the common occurrence of this species in trawl bycatch, it is likely to occur close to sand and other soft bottom substrates.

Notes on the Biology and Behaviour

Growth

The species grows to around 50cm (Hutchins and Swainston, 1986; May and Maxwell, 1986, cited in Froese and Pauly, 2007). The maximum weight of a specimen reported to be this species, is around 1.23kg (taken from Port Hughes in S.A., in 1996) (Australian Anglers Association Records Authority, 2004).

Diet

Members of the Diodontidae feed on small molluscs (Nelson et al., 1994; Parks Victoria, 2006).

Other Notes on the Biology

Two forms of the species are recognised. A shallow-water form has scattered dark spots dorsally. The deep-water form has yellow blotches on the sides (Australian Museum, 2005i).

Fisheries Information

Commercial – Commonwealth fisheries

Generally, A. pilatus is often caught by trawlers (Hutchins and Swainston, 1986).
The species is a commonly caught and discarded bycatch species in a number of fisheries in southern Australia. State fishing agencies reportedly manage the catches of Australian Burrfish that are taken within 3 nautical miles (NM) of the coast, and the Commonwealth manages catches taken outside of 3 NM (AFMA, 2002a). Even though the species is not edible, and not targeted, Commonwealth-licensed fishers who have a concession to use methods other than trawl (i.e. gillnet, fish hook, shark hook), are permitted to catch Australian Burrfish outside of 3NM in S.A., with no restrictions on catch (AFMA, 2004e).
Australian Burrfish is part of the bycatch in the Commonwealth-managed Southern and Eastern Scalefish and Shark Fisheries (SESSF) (AFMA, 2002a). The species is discarded in the Gillnet, Hook and Trap Fishery (Bromhead and Bolton, 2005), and Great Australian Bight Trawl Fishery (Daley et al., 2006).
In the otter trawl sub-fishery of the South East Trawl Fishery (SETF), an Integrated Scientific Monitoring Program (ISMP) reported that in 1054 trawl shots, about 29.4 tonnes of A. pilatus specimens were discarded (Wayte et al., 2004), which is an average of 30kg per trawl shot. In the Danish seine sub-fishery of the SETF, the ISMP recorded a much smaller total bycatch, of 132.5kg (all discarded) in 26 shots.
In the Great Australian Bight Trawl Fishery, bycatch sampling in 2000 and 2001 (Brown and Knuckey, 2002) showed that A. pilatuswas observed in 111 of the 209 trawl shots; the average quantity discarded was 16kg per trawl shot (Brown and Knuckey, 2002).
pilatus is a minor bycatch in the Commonwealth-managed Small Pelagic Fishery, recorded in less than 40% of trawl shots, and amounting to less than 1% of the catch (AFMA, 2005).

Commercial – State Fisheries

In New South Wales, the species is part of the discarded bycatch in the Ocean Fish Trawl fishery, and, to a lesser extent, in the Ocean Prawn Trawl fishery. In the Ocean Fish Trawl (shelf sector and south sector), fishery independent surveys showed that the frequency of occurrence of A. pilatus across all trawls in each of these sectors was approximately 74% (N.S.W. Department of Primary Industries, 2004).
A. pilatus is recorded in the bycatch in the prawn trawl fishery in Spencer Gulf, South Australia. For example, 38 Australian Burrfish were recorded from 32 trawl tows, in a sampling program during the mid 1990s (Carrick, 1997). During a more recent bycatch program (Dixon et al., 2005), the species was not included in a list of significant bycatch species, and is likely to have been grouped in the “miscellaneous fish” category, for which species identities of catches were not provided.
The species is promoted in the aquarium industry; however quantitative data on capture of Australian Burrfish for that trade are not available for this report.

Recreational

Although the species is not usually targeted, some recreational fishing clubs and associations keep records of the maximum sizes of specimens caught (e.g. Australian Anglers Association, 2004; Australian Anglers Association Inc., W.A. Division, 2005).

Vulnerable Characteristics of the Species

The species commonly occurs near soft bottoms in deeper waters of the continental shelf, and its distribution overlaps with many of the trawl (and other net) fisheries in southern Australia. Due to its spiny, inflatable body, Australian Burrfish easily gets entangled in fishing nets (May and Maxwell, 1986, cited in Froese and Pauly, 2007).
Diodontid fish often aggregate, which increases their vulnerability to capture (e.g. by trawls).

Threatening Processes

A study of the susceptibility of trawl-caught fishes to population impacts (Stobutski et al., 2001) ranked fish bycatch species according to two overriding characteristics (based upon biological and ecological criteria): (i) the susceptibility to capture and mortality due to prawn trawling, and (ii) the population's capacity to recover after depletion. The rank of each species on these two characteristics determined its relative capacity to sustain trawling, and therefore its priority for research and management. Species that were the least likely to be sustainable included those in the Diodontidae. These species are highly susceptible to capture by trawls, they are benthic or demersal, their primary habitat is soft sediments, and their diet may include prawns, or other species found in prawn grounds. The recovery capacity of these species is also low, with the estimated removal rate by trawling (Stobutski et al., 2001).
Australian Burrfish was 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). Studies have shown that the Australian Burrfish suffers barotrauma when hauled in trawls, and A. pilatus was classified overall as a “high risk” species in terms of population impacts from trawl fishing (see N.S.W. Department of Primary Industries, 2004).
In a draft ecological risk assessment of the South East Trawl and Danish Seine Fishery (Wayte et al., 2004), 4 “productivity attributes” and 6 “attributes of susceptibility” for A. pilatus were used to categorise it as a “medium risk” species in terms of susceptibility to population impacts from trawling. Similarly, in a draft ecological risk assessment of the Great Australian Bight Trawl fishery, this species was listed as being at “medium risk” of population impacts from operation of the fishery (Daley et al., 2006).

Research and Management Requirements

More information is required on the distribution and relative abundance (particularly in South Australia).
There is little information on reproduction, and the population dynamics of this species, including annual recruitment strength.
If possible, an assessment of survival rate of trawl-caught, discarded specimens is required, particularly in the Commonwealth-managed fisheries in which this species is caught in large numbers. Even if this research is not undertaken, measures to reduce the large bycatch of Globefish are certainly required.

Other Information

The species is found in a number of marine sanctuaries in Victoria, such as Beware Reef (Bird and Watson, 1993, cited in Plummer et al., 2003).