© 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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Johnston’s Weedfish / Broad-Headed Weedfish

Family Name:	Clinidae
Scientific Name:	Heteroclinus johnstoni (Saville-Kent, 1886)
Recommended Status in S.A:	Data Deficient
Rationale:  Johnston’s Weedfish is included here because (i) the species is strongly site-associated in nearshore habitats, and may thus be vulnerable to habitat impacts in some areas (particularly degradation of macroalgae-covered reefs); (ii) Clinids reproduce at a small, site-associated scale (and have live young), characteristics that may increase the species vulnerability to population decline; (iii) there is no knowledge of population sizes within the range (including in South Australia), and very little is known of the biology and population dynamics; (iv) there is no knowledge of the population impacts of fishing or collecting on this site-associated species of limited dispersive ability.

Page Contents

Current Conservation Status

No listings known

Distribution

Southern Australia

Heteroclinus johnstoni has a south-eastern Australian distribution, around Tasmania, Kent Group Islands and Bass Strait; Victoria (e.g. Port Phillip Bay, Discovery Bay, Wilsons Promontory, and other areas), and South Australia (Edgar, 1984, 1991; Hutchins and Swainston, 1986; Kuiter, 1996b; Barrett and Wilcox, 2001; Plummer et al., 2003; Edmunds et al., 2003).
IMCRA Technical Group (1996) considered H. johnstoni to be one of the indicator species for the Tasmanian Province, which extends from the north-eastern tip of Tasmania at Cape Naturaliste, encircling the west, south and east coasts, up to Cape Grim at its north-western extremity.
The species is considered to be common on nearshore reefs in Victoria (Edmunds and Hart, 2003).
It is noted that Griffiths (2003a) and Griffiths et al. (2004) reported a Heteroclinus species identified as H. johnstoni amongst the rock pool fish fauna at Bass Point in New South Wales, yet N.S.W. is not generally considered to be part of the geographic range (see above).
Hutchins and Swainston (1986) reported Eyre Peninsula in S.A. as the western limit; Hoese et al. (in Gomon et al., 1994) and Edgar (2000) reported Kangaroo Island in S.A. as the western limit. It is noted that a specimen identified by D. Hoese as H. johnstoni has been recorded from the Port Lincoln area; hence Eyre Peninsula is accepted here as the currently known western limit.

South Australia

Examples of locations in S.A. where the species has been recorded include lower Eyre Peninsula (e.g. out of Coffin Bay); south-western Spencer Gulf (e.g. Port Lincoln coast), eastern Spencer Gulf (e.g. Port Hughes) and other parts of Spencer Gulf; southern Yorke Peninsula (e.g. Daly Head); northern Kangaroo Island (e.g. Western River Cove, Emu Bay); north-eastern Kangaroo I. (e.g. Hog Bay area); south-western Kangaroo I.; Encounter Bay; metropolitan coast of Gulf St Vincent (e.g. Brighton / Seacliff area); Port Noarlunga; southern Fleurieu (e.g. Normanville / Carrickalinga area); Encounter Bay (e.g. Rosetta Head) and islands; and lower South-East (Hoese et al., in Gomon et al., 1994; Reef Watch, 2003; Australian Underwater Federation Inc., 2003; S.A. Museum records 1959, 1968, 1982, 1984, 1994; photograph by D. Muirhead, 2002; photograph by J. Lewis, 2004; Australian Anglers Association, 2005; Edgar et al., 2006; S.A. Museum records, Museum of Victoria records, cited in OZCAM database, 2008).

Habitat

H. johnstoni occurs on exposed reef, from the intertidal to around 50m depth (Kuiter, 1993, 1996b, Edgar 2000). The species is associated with macroalgae and rocks, inhabiting “shallow reef and weed areas” (Hutchins and Swainston, 1986, 2001), and “low reef on sand, with tall vegetation” (Kuiter, 1993, 1996b).
Considered to be most abundant in Tasmania, commonly seen lying on reef, under kelp cover, and occurring in habitats with greater wave turbulence, compared with other weedfish species (Edgar, 2000).
Juveniles are cryptic under rocks or in ledges, and large adults are often seen in more exposed areas (Kuiter, 1996a).
H. johnstoni has also been recorded in shallow rock pools (e.g. reportedly in N.S.W. – see Griffiths et al., 2004). In the Discovery Bay Marine Park, near the S.A. / Victorian border, H. johnstoni lives in intertidal pools, and shallow subtidal gutters in the rock platform (P. Arnold pers. comm., cited by Parks Victoria, 2002b, and Plummer, 2003).
In the Eagle Rock Marine Sanctuary in Victoria, H. johnstoni lives within beds of smaller macroalgae under the kelp canopy (Parks Victoria, 2004).
In the southern metropolitan area of South Australia, H. johnstoni has been recorded in reef habitat with brown macroalgae (including kelp), and Caulerpa green macroalgae (S.A. Museum record, 1982).

Notes on the Biology

Growth

H. johnstoni is a large weedfish, and grows to around 40cm (Hoese et al., in Gomon et al., 1994; Kuiter, 1996b).
The Australian Underwater Federation has reported that the record size of H. johnstoni taken by spearfishing was 0.85kg, being a specimen taken in 1971, at Carpenters Rocks in S.A. (Hutchins and Swainston, 2001; Australian Underwater Federation, Inc., 2003). Another example of a large recorded weight is 0.36kg, being a specimen taken in 2000, in Encounter Bay in S.A. (Australian Anglers Association, 2005).
No estimates of longevity were found for this report; however, it is noted that post-settlement growth is rapid, and a study of 12 weedfish species in south-eastern Australia showed that most of the reproductive populations consist of fishes in the 1 + year-class (Gunn and Thresher, 1991).

Diet

H. johnstoni is a benthic predator, and eats shrimps, crabs and small fish (Parks Victoria, 2004).

Reproduction

Temperate weedfishes are viviparous, many are “super-foetate” (simultaneously developing multiple batches of eggs and/or embryo) and reproduce over several months in spring and summer (Gunn and Thresher, 1991). Maternal investment in the nutrition of the young is high. After parturition, the larvae spend from 3 to 7 weeks in the plankton, primarily in in-shore waters (Gunn and Thresher, 1991).

Fisheries / Collecting

There are reports (e.g. Marine Aquarium Societies of Australia) of the species being collected in Victoria for home aquaria.

Vulnerable Characteristics of the Species and Threatening Processes

Members of the Clinidae are strongly site-associated in coastal areas of seagrass and macroalgae, and processes which damage such habitats may adversely affect populations of clinid species.
Members of the family are viviparous (bear live young), and therefore reproduce at a local, site-associated level, and have low dispersive ability, characteristics that can increase vulnerability to processes causing population decline.

Fisheries Information

The species is reported to be commonly taken on hook and line in Tasmania (Hoese et al., in Gomon et al., 1994).
There are records of the species being taken by spear fishers (e.g. AUF, Inc., 2003).
H. johnstoni is collected in Tasmania for the aquarium industry. The permitted annual catch limit is 150 individuals, with a fishing block limit (6 x 6 nautical miles) of 25 individuals (DPIWE Tasmania, 2005b; Australian Government DEH, 2005b).

Research Requirements

As indicated in the section above, very little is known of the biology and population dynamics of this species. Information on the distribution, relative abundance, habitat requirements and biology may help in better determining the susceptibility of weedfishes to threats such as habitat degradation. However, the difficulty of determining distribution and relative abundance of small, cryptic, benthic species such as weedfishes is noted.

Management Requirements

H. johnstoni is site-associated in macroalgae habitats. Habitat in the deeper part of the depth range (i.e. the species occurs to around 50m) is less vulnerable to impact compared with macroalgae stands in the nearshore area. Habitat protection is required from processes that result in physical removal of coastal marine macroalgae stands, or degrade the quality of macroalgae habitat (e.g. though impacts of eutrophication, siltation etc).
Recreational fishing regulations may be required, given that this is a site-associated, locally reproducing species, and there is no knowledge of population sizes, or of the sustainability of fishing H. johnstoni.
Research and monitoring may be required to determine whether an illegal trade for H. johnstoni (as an aquarium fish) exists.

Other Information

Johnston’s Weedfish is the largest Clinid found in southern Australia, and one of the largest in the world (Hoese et al., in Gomon et al., 1994).
H. johnstoni is one of the reef fish species whose sightings are monitored as part of the Reef Watch community program in South Australia.
The species occurs in a number of marine protected areas in Victoria, such as Wilsons Promontory, Phillip I., Port Phillip Heads, Discovery Bay, and Bunurong Marine National Parks, and Eagle Rock Marine Sanctuary (Parks Victoria, 2002b; Plummer et al., 2003; Edmunds et al., 2003). In northern and north-eastern Tasmania, the species has been recorded in low numbers on reefs at a several sites have been proposed as marine protected areas (Barrett and Wilcox, 2001).

Support for S.A. Listing:

Barry Hutchins (ex-West Australian Museum), who recommended Data Deficient category.