© 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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Western Smooth Boxfish / Blue Boxfish / Robust Boxfish

Family Name:	Aracanidae (or Ostraciidae, sub-family Aracaninae)
Scientific Name:	Anoplocapros amygdaloides Fraser-Brunner, 1941 = A. robustus (Fraser-Brunner, 1941)
Recommended Status in S.A:	Data Deficient, possibly Rare E(ii) in S.A.
Rationale:  Included here because (i) this south-western species appears to have a limited presence in South Australia, with few records known; (ii) generally, temperate boxfishes are strongly site-associated / territorial and haremic, characteristics that can increase the vulnerability of populations to localised impacts; (iii) juveniles and females of A. amygdaloides are reported to occur in the near-shore area, on reefs in bays, near seagrass beds, and near jetties, and thus may be vulnerable to habitat impacts in some coastal areas; (iv) depth and spatial segregation of the sexes could increase the vulnerability of the species to population impacts, if one of the sexes is fished to a greater extent than the other; (vi) the species is part of the bycatch in a number of trawl fisheries (mainly in the Great Australian Bight and south-western W.A.), and trawl-caught specimens are unlikely to survive; (vi) the species is part of a growing trade in specialist aquarium fishes, and potential impacts on populations apparently have not been investigated; and (vii) there is little existing information about the biology, population dynamics, or relative abundance of this species across its range.

Page Contents

Current Conservation Status

No listings known

Distribution

The species is known mainly from southwestern Australia, from the eastern portion of the Great Australian Bight (GAB) in S.A., to Shark Bay in W.A. (Hutchins and Swainston, 1986; Kuiter, in Gomon et al., 1994; Edgar, 2000). There is a specimen reported from the border area of W.A. and S.A., collected 95km southwest of Eucla, at 200m deep (Museum of Victoria record A 3363, cited in OZCAM database, 2007). There appear to be few published records of this species in South Australia, other than (i) the occurrence in trawl samples from the Great Australian Bight (W.A. Museum data, cited by B. Hutchins, pers. comm.., 2007) and in the South East Trawl Fishery (Bromhead and Bolton, 2005); (iii) CSIRO Marine Research records (CA1157, CA1158, CA 3477 and CA 3488, Australian National Fish Collection records, cited in CSIRO, 2006) of specimens taken in the Ceduna area in 1975, and in other parts of the Great Australian Bight, in 1981; and (iii) single specimens recorded at West I. and The Bluff (Encounter Bay) during surveys in 2005, and reported to be A. amygdaloides (Edgar et al., 2006), but unverifiable (G. Edgar, University of Tasmania, pers. comm., 2006).

Habitat

Western Smooth Boxfish has been recorded in a variety of habitat types.
The species is found on coastal rocky reefs, and on deeper reefs in offshore waters on the continental shelf (Hutchins and Thompson, 1983; May and Maxwell, 1986, Kuiter, 1996a).
Kuiter (in Gomon et al., 1994) and Edgar (2000) reported the habitat as being moderately exposed reef and (in inshore areas) seagrass.
Larger adults, particularly males, mainly occur in deeper offshore waters (Kuiter, 1996a; Edgar, 2000). In the main part of the range (W.A.), females are considered to be “moderately common” on shallow coastal reefs, particularly near seagrass beds (Edgar, 2000). Juveniles and sub-adults occur in estuaries (Potter et al., 1990; Kuiter, 1996a), often in silty conditions.
In W.A., the species has been recorded during a survey over predominantly sandy substrate, in waters 5 – 35m deep (Hyndes et al., 1999), and, during that survey was one of a suite of species that contributed to 80% of the total biomass of fish recorded during that survey (Hyndes et al., 1999, cited by Platell and Hall, 2006). Similarly, in other parts of south-western Australia, the species has been recorded (in low abundance) in non-reef habitats, using set nets and bottom trawls/dredge (Hutchins, 2005).
The species is also commonly recorded under jetties / piers (Kuiter, 1996a) and also shipwrecks, particularly in W.A. (Recreational diving reports from W.A., 2001-2005).
Although the reported the depth range is (2m) 5m – 100m (May and Maxwell, 1986; Kuiter, in Gomon et al., 1994; Edgar, 2000), it is noted that there is a specimen reported to be this species, from 200m deep (Museum of Victoria record, cited in OZCAM database, 2006), and W.A. Museum has record from 250m, in the Great Australian Bight (B. Hutchins, W.A. Museum, pers. comm., 2007).

Notes on the Biology and Behaviour

Growth

The species grows to around 39cm (Hutchins and Thompson, 1983; Edgar, 2000).
The maximum weight recorded is around 1.233kg, being a specimen taken from Bunbury in southern W.A. (Australian Anglers Association Records Authority, 2003).  Another large specimen was reported to be 1.15kg (Hutchins and Thompson, 2001).

Behaviour

In general, boxfishes are territorial and haremic (Nelson, 1994, cited in Froese and Pauly, 2007); however, based on the observed distribution records of A. amygdaloides, spatial segregation of the sexes and life stages is likely in this species.

Diet

In general, boxfishes are benthic feeders (Kuiter, 1996a) that eat small sessile invertebrates, and algae (Nelson, 1994, cited in Froese and Pauly, 2007). Some dietary studies have been undertaken for individuals of this species that were recorded on predominantly sandy substrate (Hyndes et al., 1999).

Reproduction

According to Kuiter (2000), temperate boxfishes are protogynous hermaphrodites, and when in captivity, females of some species in the Aracanidae have been observed transforming into males.

Other Notes on the Biology

The males and females differ in colour, body shape, and markings. Males are larger, elongate, and pale blue colour, with small spots and “scribbles” over the body surface. Females and juveniles have a shorter, deeper body than the males. Juveniles are orange, with white bars and black spots. Females have a cream- or pale brown-coloured body, with yellow-ringed black spots (Hutchins and Swainston, 1986; Gomon et al., 1994; Kuiter, 1996a).

Fisheries Information

Commercial

The Western Smooth Boxfish is known from trawling grounds in southwestern Australia (Hutchins and Swainston, 1986, 2001), where it is part of the bycatch. Boxfish species are caught in small numbers and discarded, as part of the bycatch in the W.A. temperate demersal gillnet and demersal long-line fisheries (McAuley and Simpfendorfer, 2003).
The species has been reported as part of the discarded bycatch in the South East Trawl Fishery, and the Great Australian Bight Trawl Fishery (Bromhead and Bolton, 2005). In the Danish seine sub-fishery of the South East Trawl Fishery, the species is reported to be a very minor part of the bycatch (i.e. 1kg per shot discarded) (Wayte et al., 2004).
Western Smooth Boxfish is used in the aquarium fish trade; however the extent to which the species is collected in South Australia for this purpose, is not known for this report. It is noted that the Western Smooth Boxfish is amongst the top 40 of about 250 fish species taken commercially in W.A. for the aquarium trade. Since 1976, around 771 Western Smooth Boxfish have been taken by this fishery (W.A. Department of Fisheries, 2004b). Between the years 2000 and 2003, around 79 specimens of A. robustus per year were collected in W.A. for the aquarium trade (W.A. Department of Fisheries, 2004b).

Recreational

Boxfish species are caught in small numbers by recreational fishers. Some fishing clubs and associations keep records of the maximum sizes caught (e.g. Australian Anglers Association Inc., W.A. Division, 2005).
The species is occasionally taken be spear fishers, and one of the maximum sizes recorded (1.15kg) was a specimen taken by spearfishing (Hutchins and Thompson, 1983).

Vulnerable Characteristics of the Species

The species is not regularly recorded in South Australia, and may be naturally uncommon.
In general, boxfishes are site-associated, territorial, haremic species, characteristics that can increase their vulnerability to site-specific impacts.
The reported shallow water habitats of females and juveniles (namely, shallow subtidal reefs, coastal seagrass beds, and estuaries) are subject to land-based impacts in a number of areas where this species occurs (e.g. metropolitan coast of W.A., and parts of south-western W.A.). Long term degradation of such habitats may affect populations of site-associated fish species; however data are lacking for boxfishes.

Threatening Processes

The species is vulnerable to mortality as fisheries bycatch, in part of its range. For example, the Western Smooth Boxfish is reported from the trawl grounds in southwestern Australia (Hutchins and Swainston, 1986, 2001). It is also likely to be one of the boxfish species caught in small numbers and discarded, as part of the bycatch in the W.A. temperate demersal gillnet and demersal long-line fisheries (McAuley and Simpfendorfer, 2003). Although fisheries in southwestern Australia take the species as bycatch, the extent to which this process threatens populations is not known. In New South Wales the closely related species A. inermis (Eastern Smooth Boxfish) is a very commonly caught bycatch species in the fish and prawn trawl fisheries in estuaries and in deeper waters on the continental shelf (Gray and Kennelly, 2001; N.S.W. Department of Primary Industries, 2004; Wayte et al., 2004). Studies have shown that the Eastern Smooth Boxfish suffers barotrauma when hauled in trawls, and A. inermis was classified overall as a “high risk” species in terms of population impacts from trawl fishing (see New South Wales Department of Primary Industries, 2004). Similar risks may apply to populations of A. amygdaloides when specimens are captured in trawl fisheries.
Removal from the wild for the international aquarium trade is an additional source of mortality. Given that temperate boxfishes such as the White-Barred Boxfish (see synopsis) have become more popular in the specialised international aquarium market in recent years, it is possible that the trade in Western Smooth Boxfish may also increase if demand for temperate boxfish species increases. There has been no assessment of the sustainability of the aquarium industry catches.

Research and Management Requirements

More information is required on the distribution (particularly in South Australia) and abundance of this species. Also not well known is the habitat of the Western Smooth Boxfish in deeper waters, where larger specimens (usually males, according to Kuiter, 1996a and Edgar, 2000) are more often recorded. The life history is not well known, and information on the habitats, habits, diet (Platell and Hall, 2006), spatial segregation of sexes and/or life stages, and reproductive cycle, may also assist in managing potential impacts on this species.
More information is required on the extent to which this species is captured in fisheries in southwestern Australia, and the Great Australian Bight.  Pending the results of population and fisheries assessments, methods may need to be devised to limit the bycatch of this species.
All reef fish species taken 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

Anoplocapros amygdaloides Fraser-Brunner, 1941 and Anoplocapros robustus (Fraser-Brunner, 1941) are considered to be the same species (CSIRO, 2007). Both A. amygdaloides and A. robustus were described in the same paper, each with a type locality of “Australia”, but A. robustus is a female of the western form; A. amygdaloides is a juvenile - either the eastern or western form, but likely to be closest to the eastern form, which would make it a junior synonym of A. inermis, the eastern species (B. Hutchins, W.A. Museum, pers. comm., 2007). In W.A., the name A. robustus is used (B. Hutchins, W.A. Museum, pers. comm., 2007).
The very similar eastern species, Eastern Smooth Boxfish A. inermis, found in southern Queensland, NSW and Victoria (Hutchins and Swainston, 1986; Kuiter, 1996a; CSIRO, 2007).
In W.A., Western Smooth Boxfish is one of the species recorded at a protected reef in Cottesloe, during fish counts organised by the Department of Conservation and Land Management, in conjunction with local dive groups.