© 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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Crested Threefin / Crested Triplefin

Family Name:	Tripterygiidae
Scientific Name:	Trinorfolkia cristata (Kuiter, 1986) = Norfolkia cristata
Recommended Status in S.A:	Data Deficient
Rationale:  The Crested Threefin is included here because it (i) appears to have a limited known distribution, found to date only in South Australia; and (ii) occurs in the near-shore area, and members of the Tripterygiidae family are strongly site-attached, and guard benthic eggs, characteristics that may make them vulnerable to localised impacts. There is little information on the nature and extent of threats. Processes that impact upon the extent, quality and cover of nearshore reefs may adversely affect populations of site-associated nearshore reef fishes such as T. cristata, but there are no specific data. The species has been commonly recorded, and appears not to be rare within the known range. Due to its apparent endemic status, it may qualify for listing internationally, but is unlikely to qualify for listing as Rare within South Australia.

Page Contents

Current Conservation Status

There are no formal listings known; however the species was previously reported to be rare (Edgar, 2000), likely due to its endemic nature within S.A., and therefore limited geographic range in southern Australia.

Distribution

To date, confirmed records of Trinorfolkia cristata have been recorded only in South Australia (Fricke, 1994; Kuiter, in Gomon et al., 1994; B. Hutchins, W.A. Museum, pers. comm., 2006; M. Gomon, Museum of Victoria, pers. comm., 2006).
Records are known from various parts of S.A., e.g. Flinders Island in the Investigator Group, and Ceduna area, in the eastern Great Australian Bight; Spencer Gulf (e.g. Port Hughes); western Gulf St Vincent (e.g. Edithburgh Jetty); eastern Gulf St Vincent / Fleurieu Peninsula (e.g. Seacliff Reef, Second Valley, and Cape Jervis area); Victor Harbor / Encounter Bay area, and parts of north-eastern Kangaroo Island, including Kingscote, and sites in Eastern Cove (e.g. Baudin Beach), and also along the Dudley Peninsula (Kuiter, 1983; Hutchins and Swainston, 1986; Fricke, 1994; Kuiter, in Gomon et al., 1994; photograph by D. Muirhead, 2000, in MLSSA, undated; photographs by D. Muirhead, 2001, 2002; Edgar, 2000; Edgar et al., 2006; J. Baker, unpubl. data., 2007-08; photograph by A. Brown, 2008; Shepherd et al., 2008; Australian Museum records, SA Museum records, WA Museum records, Museum of Victoria records, cited in OZCAM database, 2004, 2008).
In terms of distribution, N. cristata appears to replace N. clarkei in shallow rocky reef areas in South Australia (Kuiter, in Gomon et al., 1994). The species has been recorded commonly at various dive sites in S.A., during the past 3 decades (Kuiter, in Gomon et al., 1994; D. Muirhead, pers. comm., 2005).
IMCRA Technical Group (1996) considered Trinorfolkia cristata to be one of the indicator species for the Gulfs Province, which comprises Spencer Gulf and Gulf St Vincent, and Kangaroo Island, extending out to the shelf break, with a western boundary at Port Lincoln, and the eastern edge being just east of Kangaroo Island.

Habitat

Found in the intertidal and shallow subtidal, in caves, on vertical rock surfaces and other parts of rocky reef (e.g. on coralline algae-covered reef surfaces), and also on and around jetty pilings (S.A. Museum data, 1984; Fricke, 1994; Kuiter, in Gomon et al., 1994; Kuiter, 1996a; J. Baker, pers. obs., 2007-08).
The species occurs on shallow protected reefs in coastal bays (Hutchins and Swainston, 1986).
The recorded depth distribution is 0m – 15m (Fricke, 1994, cited in Froese and Pauly, 2008).

Notes on the Biology

Growth

The species grows to 7cm - 8cm (Kuiter, in Gomon et al., 1994) or 9cm (Hutchins and Swainston, 1986).

Reproduction

The species belongs to a family of strongly site-associated fishes that have “nests” where the eggs are guarded by the male.

Vulnerable Characteristics of the Species

The species is thought to be endemic within South Australia, and therefore has a limited geographic range (although it is commonly recorded within the range).
Members of the family are strongly site-attached, and guard benthic eggs, characteristics that may make them vulnerable to habitat impacts.

Threatening Processes

There are few known threatening processes. The species is not fished, and not known to be collected for the aquarium trade. Given that the Crested Threefin is strongly site-associated in intertidal and shallow subtidal reef habitats, over a narrow depth range, processes that impact upon the extent, quality and cover of nearshore reefs may adversely affect populations of this species, but there are no specific data.

Research Requirements

Specific surveys of small benthic fishes on intertidal and shallow subtidal reefs across South Australia may provide a better indication of the full distribution and relative abundance of less easily observed species such as Trinorfolkia cristata.

Support for S.A. Listing:

Graham Edgar (University of Tasmania), under Data Deficient category