© 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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Milward’s Weedfish

Family Name:	Clinidae
Scientific Name:	Heteroclinus sp. 6 (Hoese et al., in Gomon et al., 1994)
Recommended Status in S.A:	Data Deficient
Rationale:  Milward’s Weedfish here because (i) the species is strongly site-associated in nearshore habitats, may occur over a narrow depth range, and may thus be vulnerable to habitat impacts in some areas (such as degradation of nearshore seagrass beds and macroalgae-covered reefs), but there are no specific data; (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 are very few records known from South Australia, and the full distribution within this State, and the habitat requirements, are not known; (vi) 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.

Page Contents

Current Conservation Status

No listings known

Distribution

Southern Australia

Ranges across southern Australia, from Port Phillip Bay in Victoria, to Brenton Bay in W.A., including northern Tasmania (Hoese et al., in Gomon et al., 1994).
The Port Phillip Heads area in Victoria is presumed to be the eastern limit of the species (Plummer et al., 2003).

South Australia

There are few records from South Australia. Examples of locations in S.A. which the species has been recorded include northern Kangaroo Island (e.g. Stokes Bay), and north-eastern Kangaroo Island (e.g. American River) (photographs by D. Muirhead, 2002; S.A. Museum records of "Heteroclinus milwardi", cited in OZCAM database, 2008; Gillanders et al., 2008); and southern Yorke Peninsula (e.g. Port Moorowie) (Baker et al., 2008a).

Habitat

Milward’s Weedfish is associated with rocks, macroalgae and seagrass, in shallow coastal water (Hoese et al., in Gomon et al., 1994).
There is a record from 14m deep, on northern Kangaroo Island (photographs by D. Muirhead, 2002).

Notes on the Biology

Growth

Heteroclinus sp. 6 is reported to grow to 10cm (Hoese et al., in Gomon et al., 1994).
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).

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).

Vulnerable Characteristics of the Species and Threatening Processes

Members of the Clinidae are site-associated in coastal reef areas of with 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.

Research Requirements

Very little is known of the distribution, relative abundance and habitats requirements of this  species within S.A., as well as the biology and population dynamics. 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.
Nearshore fish surveys in shallow seagrass beds and macroalgae-covered reefs should be aware of the potential presence of site-associated Clinids such as H. sp. 6, and when found, the presence of such species should be recorded. Weedfish are difficult to identify in situ, and a photographic record should be taken where possible.

Management Requirements

Milward’s Weedfish is site-associated in nearshore habitats. Habitat protection is required from processes that degrade the quality of seagrass beds and nearshore reef habitats (e.g. physical damage from dredging / channel clearing, shallow water boating etc; and also eutrophication; siltation etc).

Other Information

The species is closely related to H. whiteleggii from N.S.W., which has two ventral fin rays (Hoese et al., in Gomon et al., 1994).