© 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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Long-finned Boarfish / Longfin Boarfish / Black-spotted Boarfish

Family Name:	Pentacerotidae
Scientific Name:	Zanclistius elevatus (Ramsay and Ogilby, 1888)
Recommended Status in S.A:	Data Deficient, possibly Near Threatened
Rationale:  Although the Long-finned Boarfish has a broad geographic range (across southern Australia and New Zealand) and large depth range, it is included here because (i) it is a site-associated reef fish that has been commonly caught as a saleable by-product in Commonwealth fisheries, and as discarded bycatch in State-managed fisheries; (ii) there appears to be no knowledge of population sizes / relative abundance, or populations dynamics of this species  across the range; (iii) there are virtually no controls over the capture of Long-finned Boarfish, and little information about the sustainability of fishing for this species; (iv) like other members of the Pentacerotidae, Long-finned Boarfish is likely to be a bottom feeder, and have a strong habitat association; therefore, habitat damage in continental shelf waters due to processes such as trawling may have a consequent negative impact on boarfish populations; however no studies have been undertaken; and (v) at least three assessments have ranked Z. elevatus as a “high risk” or “medium-high risk” species, and indicated that the species is susceptible to population impacts due to being taken as by-product (drop-lining, and trawling). Given these factors, the status of Long-finned Boarfish populations should be investigated. There is a possibility that this species may be Near Threatened in deeper waters off South Australia and other southern States, particularly in areas where the species is taken by trawls  (i.e. in the vicinity of the SETF and GABTF fisheries) ands drop-lines (GHAT fishery).

Page Contents

Current Conservation Status

New Zealand: Range Restricted (Department of Conservation, New Zealand, 2005)

Distribution

General

Z. elevatus occurs across southern Australia, Tasmania and New Zealand (May and Maxwell, 1986).
In New Zealand, the species is described as warm temperate, and has been recorded from all sides of the North Island (Francis, 1996).

Southern Australia

In Australia, the species has a broad distribution across the southern half of the continent, from northern N.S.W, through to Western Australia. In W.A., records have been recorded as far north as the Houtman Abrolhos / Kalbarri area (Museum of Victoria record, Australian National Fish Collection records, cited in OZCAM database, 2007). In N.S.W., there are old records (1910) from as far north as the Queensland / New South Wales border (Australian Museum records, cited in OZCAM database, 2007), but the validity of these is not known for this report.
The species has a patchy distribution, but is considered to be relatively common in some areas (Hardy, in Gomon et al., 1994). The Long-finned Boarfish is rarely seen in eastern (or southern) Australia due to its preference for deeper waters (Kuiter, 1996a).

South Australia

Examples of locations in S.A. where the species has been recorded include the deeper waters of the western, central and eastern Great Australian Bight (GAB), from where numerous records have come; south-eastern GAB; Investigator Group islands; deeper waters north-west, west and south of the Coffin Bay Peninsula; the upper south-east of S.A., and coastal waters off the South Australia / Victoria border (Brown and Knuckey, 2002; CSIRO Marine Research records, cited in CSIRO, 2007; South Australian Museum records, Museum of Victoria records [including MAFRI trawl survey data], cited in OZCAM database, 2007).
The majority of published records in S.A. come from the Great Australian Bight (e.g. CSIRO Marine Research data, cited in CSIRO, 2007).

Habitat

The Longfin Boarfish inhabits deeper waters on the continental shelf and upper slope of southern Australia (May and Maxwell, 1986; Hutchins and Swainston, 2001).
The maximum depth recorded is deeper than 200m, and many specimens have been recorded in the range 100m – 175m (CSIRO et al., 2001).
The upper depth limit may be about 30m (Robins et al., 1991, cited in Froese and Pauly, 2006), but in southern Australia it is generally reported to be about 50m (CSIRO et al., 2001). At the Poor Knights Islands in New Zealand, some Z. elevatus individuals have been recorded in relatively shallow water, below 15m (e.g. Brook, 2002).

Notes on the Biology

Z. elevatus grows to between 33cm (May and Maxwell, 1986) and 40cm (Hardy, in Gomon et al., 1994).

Fisheries Information

Commonwealth-managed Fisheries

Z. elevatus is taken by trawlers in southern Australia (Hutchins and Swainston, 2001), and the official marketing name is Black-spotted Boarfish / Blackspot Boarfish, although it is called various other names in southern Australian States (Australian Government Department of Agriculture, Fisheries and Forestry web site, 2004).
The species is part of the bycatch in the Commonwealth-managed Southern and Eastern Scalefish and Shark Fisheries (SESSF) (AFMA, 2002a). Boarfish species taken in the bycatch of commercial fishing in Commonwealth-managed waters are not usually recorded to species level, although some specific records of Z. elevatus do exist, and are provided below. Catch data for boarfish species as a group are provided above, in the section on the family Pentacerotidae.
The species is part of the by-product taken in the Commonwealth-managed Gillnet, Hook and Trap Fishery (GHAT), in which it is caught with scalefish drop-lines (Webb et al., 2004; Bromhead and Bolton, 2005). During a bycatch monitoring program in 2002-03, the species was recorded in only one drop-line shot, and the specimen (1kg) was retained (Webb et al., 2004). Given that the species is considered to be at “high risk” of impact from drop-line fishing (see assessment by Webb et al., 2004), it is likely that the results from the 2002-03 bycatch monitoring program were not representative of the numbers of this species that have been caught in the GHAT fishery during past years.
According to AFMA (2002a), nearly 0.63t of Z. elevatus were caught in the SETF in 2001, and almost all 99% was discarded. In the otter trawl sub-fishery of the South East Trawl Fishery (SETF), an Integrated Scientific Monitoring Program (ISMP) reported that in 442 trawl shots, about 1.54 tonne of Z. elevatus was discarded (and only 22kg were retained), which is an average of about 3.5kg per trawl shot discarded (Wayte et al., 2004). In the Danish seine sub-fishery of the SETF, the ISMP reported that in 4 shots, about 2.7 kg of Z. elevatus were discarded (Wayte et al., 2004).
The Longfin Boarfish is part of the bycatch in the Great Australian Bight (GAB) Trawl Fishery. Bycatch sampling reported by Brown and Knuckey (2002) showed that Z. elevatus were caught during the sampling periods in 2000 and 2001, and all of those caught were discarded. During the sampling period, Longfin Boarfish was observed in 80 of the 209 trawl shots; the average quantity discarded was 10.2kg per trawl shot (Brown and Knuckey, 2002). The scientific monitoring program in 2000/2001 recorded at least 0.45t in the GABTF, almost all of which was discarded (AFMA, 2002a). It is noted that Bromhead and Bolton (2005) reported that Z. elevatus is retained as by-product in the GAB Trawl Fishery.

State – Commercial

Boarfish species taken by commercial fishing in southern Australian States are not recorded to species level. For each State, examples of catch data for boarfish species as a group are provided above, in the section on the family Pentacerotidae.
In Tasmania, Z. elevatus is taken in deeper waters using trawls and gillnets (Smith and Heran, 2001). Catches of boarfish species are not separated by species. An example of commercial catches of boarfishes in Tasmania (of which Z. elevatus is one component), is provided above in the section on Pentacerotidae.
In W.A.’s Western Deepwater Trawl Fishery, Newton et al. (1994) reported that a Zanclistius boarfish was one of the 2 main species taken during exploratory fishing of the upper continental slope region from Geraldton south to Cape Leeuwin, during the early 1990s.
In New South Wales, fishery-independent surveys to assess bycatch composition in the N.S.W. Ocean Trawl Fishery have been undertaken, using ocean fish trawl and prawn trawl gear. Results showed that the percentage frequency of occurrence of Long-finned Boarfish Z. elevatus across all trawls, was 34% in the “ocean fish trawl shelf sector”; 8% in the “Wreck Bay and Tathra inshore grounds of the ocean fish trawl shelf sector”; 6% in the “ocean prawn trawl deepwater sector” and ~ 1% in the “ocean prawn trawl shelf sector” (N.S.W. Department of Primary Industries, 2004). Catches of unspecified “boarfish” species in the N.S.W. trawl fisheries, which would include Z. elevatus and others, are discussed above, in the section on Pentacerotidae.

New Zealand – Commercial

In New Zealand, Z. elevatus is listed amongst the approved species taken in the High Seas fisheries (New Zealand Ministry of Fisheries web site, 2004).

Vulnerable Characteristics of the Species, and Threatening Processes

The main threatening process is trawl fishing, in which Long-finned Boarfish is taken as saleable by-product, or discarded, depending on the fishery. The species is taken in a number of Commonwealth-managed and State-managed trawl fisheries, and no studies have been undertaken to determine population sizes of this site-associated species, or the sustainability of fishing Z. elevatus populations.
Z. elevatus is reported to suffer barotrauma when caught in bycatch, and survival of trawl caught specimens is likely to be low (N.S.W. Department of Primary Industries, 2004). In the Scalefish Drop-line sub-fishery of the GHAT, a risk assessment in 2004 ranked Z. elevatus as a “high risk” species, in terms of population impacts from drop-lining (Webb et al., 2004). Similarly, in a draft ecological risk assessment report for the South East Trawl Fishery (Wayte et al. 2004), Z. elevatus was listed as being a “medium risk” species in terms of potential population impacts from trawling, although the calculated “overall risk value” was close to the upper limit for that category, hence the species almost qualified as “high risk” in that assessment. In New South Wales, the species has been classified as being of “intermediate to high risk”, in terms of population impacts from trawl fishing (N.S.W. Department of Primary Industries, 2004). Despite this, it is noted that the species was also classified in the N.S.W. assessment as being of relatively high resilience to population impacts, due to (i) pelagic eggs and larvae (which gives a greater potential for their populations to recover from depleted stocks due to fishing mortality), and (ii) a large depth range, hence there is substantial area available to decrease the probability of encountering a trawl net. Generally, boarfishes are site-associated reef fish species that feed on the bottom. In some areas of the continental shelf and upper slope, damage to the benthos (e.g. from processes such as trawling) may have a consequent negative impact on Long-finned Boarfish populations; however no studies have been undertaken.

Research Requirements

There is little information on the relative abundance of this species across its known geographic range and depth range. Data are also lacking on the biology, habits, habitat preferences, and population dynamics of Long-finned Boarfish.
Boarfish species in the bycatch of fish trawls (State and Commonwealth waters) and prawn trawls (State waters) should be identified to species level.

Management Requirements

Measures to reduce the bycatch of this and other boarfish species in trawl fisheries should be investigated.

Other Information

The Long-finned Boarfish occurs in a number of protected areas in New Zealand, such as the Poor Knights Islands Marine Reserve (Denny et al., 2003).