© 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.

---

Frayed-Fin Goby / Krefft’s Frillgoby / Frayedfin Goby / Krefft’s Goby

Family Name:	Gobiidae
Scientific Name:	Bathygobius krefftii (= B. kreffti) (Steindachner, 1866)
Recommended Status in S.A:	Data Deficient, possibly Rare D(i) or E(ii) (for S.A. only)
Rationale:  The Frayed-fin Goby is included here because (i) it is a sub-tropical species from eastern Australia, with a limited known distribution in South Australia, known to date only from northern Spencer Gulf and various parts of Gulf St Vincent, in low numbers; (ii) it is found in shallow subtidal habitats, including seagrass beds and shallow subtidal rocks, and thus may be vulnerable to site-specific impacts in some areas; and (iii) gobies are typically benthic nest spawners and egg guarders, and hence populations may be vulnerable to localised impacts.

Page Contents

Current Conservation Status

(no listings known)
 

Distribution

Southern Australia

The species is sub-tropical, and the published distribution currently includes southern Queensland, New South Wales, and South Australia (Kuiter, 1993, 1996b; Gomon et al., 1994; Edgar, 2000). 
 

South Australia

In South Australia, examples of locations here the species has been recorded include Backy Point, north of Whyalla, in northern Spencer Gulf (Museum of Victoria record A22348 from 1997, cited in OZCAM database, 2007) and other records from the Whyalla area (M. Hammer, Aquasave, pers. comm., 2006); far northern Gulf St Vincent (GSV) (Port Arthur) (K. Smith, unpubl. data, 2004); western GSV (e.g. Black Point and Pine Point) (K. Smith, pers. comm., 2006); West Lakes, in metropolitan GSV (2 specimens, including a ripe female) (Hammer, 2006b), and the Onkaparinga Estuary mouth in eastern GSV (data by R. Gannon et al., Flinders University, cited by Hammer, 2006a and Gillanders et al., 2008).
The recent records from Gulf St Vincent are significant (see Hammer, 2006b), given that the previously published distribution within S.A. included only the disjunct population in far northern Spencer Gulf. The distribution of this species in S.A. matches relict subtropical distribution patterns for other marine fauna (Hammer, 2006b), found in northern Spencer Gulf and and/or northern Gulf St Vincent.
 

Habitat

There is some discrepancy in published reports of the preferred habitat of this species, as outlined below:
Hoese and Larson (in Gomon et al., 1994) and Edgar (2000) reported that the species is normally found in seagrass beds in coastal bays and estuaries.  Edgar (2000) also listed sheltered mud and sand habitat. The species is abundant near the mouths of estuaries along the N.S.W. coast, and is often associated with seagrass beds (Ferrell et al., 1993; Edgar, 2000; York et al., 2006; Jelbart, 2004; Jelbart et al., 2006). For example, B. krefftii was one of the 6 most abundant species recorded in Posidonia seagrass beds, during a survey of Botany Bay (Middleton et al., 1984, cited by Cappo et al., 1998). In N.S.W., the species is also known from coastal lakes, such as Illawara, Tabourie, Conjola, Burrill, Coila, Wallaga, Durras and Merimbula (Lake Illawarra Authority of N.S.W., undated; West and Jones, 2001).
In addition to shallow seagrass beds, Kuiter (1993 and 1996b) recorded the habitat as rocky estuaries. Similarly, Hutchins and Swainston (1996 and 2001) reported that this species mainly inhabits areas of rocky rubble and reef.
The preference of Bathygobius krefftii for seagrass beds is considered unusual for the genus, because most species of Bathygobius are found associated with rocky reefs or coral reefs, or rocks in mangroves (Hoese and Larson, in Gomon et al., 1994).
It is noted that in New South Wales, York et al. (2006) reported B. krefftii in beds of the invasive alga Caulerpa taxifolia, adjacent to seagrass beds (where this goby species was also present, in both Zostera and Posidonia seagrass).
In West Lakes (an artifical lake in eastern Gulf St Vincent, S.A.), B. krefftii has been recorded in structurally complex habitat, such as rocks and clumps of dead mussels (Hammer, 2006b). Artificial structure such as rock piles and debris common to the West lakes area, provide structural habitat for colonisation, but it is also considered possible that B. krefftii populations in West Lakes may be relicts from former seagrass/mangrove habitat prior to development (Hammer, 2006b).
To date, the published depth range is 0m to 6m depth (Edgar, 2000).
 

Notes on the Biology

Frayed-fin Goby grows to around 7cm (Hoese and Larson, in Gomon et al., 1994) or 9cm (Kuiter, 1993, 1996b; Edgar, 2000).
Members of the family are typically nest spawners, with males guarding the eggs (Hoese, 1998).
 

Vulnerable Characteristics of the Species, and Threatening Processes

Within South Australia, this sub-tropical species has been recorded in a limited geographical area (i.e. the gulfs region) and in low numbers.
The species is associated with estuaries and other shallow nearshore habitats. Estuaries are often subject to many pollutants, and other impacts that degrade water quality and habitat. Polluted estuarine areas can take a long time to recover as toxicants accumulate in their sediments (Pogonoski et al., 2002). Due to most population centres in Australia being located close to coastal and/or estuarine environments, estuarine habitats and their associated communities are often vulnerable to the effects of habitat degradation, and overexploitation by humans (Pogonoski et al., 2002). There are few pristine or near pristine estuaries remaining in South Australia, and most are subject to numerous impacts, including those in northern and far northern Spencer Gulf, and eastern GSV (see Bucher and Saenger, 1989; Lewis et al., 1998; Barnett, 2001; GeoScience Australia, 2001; Bryars, 2003; Baker, 2004). A more recent and equally significant stress on estuaries in S.A. (and therefore on estuarine inhabitants) is likely further reduction in freshwater inflows in the coming years, due to expansion of urban populations and rural developments in some areas, and also due to the effects of climate change in South Australia.
Gobies are benthic nest spawners and egg guarders, population characteristics that increases their vulnerability to site-specific habitat impacts.
 

Research Requirements

In South Australia, surveys are required to determine the distribution and relative abundance of this species in GSV and Spencer Gulf, and to determine whether or not the species also occurs in other warmer-water parts of S.A., such as the bays of the eastern Great Australian Bight.
When the less commonly known goby species are recorded in surveys, fish taxonomy experts should be sought to provide species-specific determinations. Voucher specimens and/or photographs should be taken.
 

Management Requirements

Ongoing programs to protect and restore estuarine function may benefit small, site-associated estuarine species such as Frayed-Fin Goby. 
Given the apparent limited distribution of this species in South Australia, coastal developments in the northern Spencer Gulf and estuarine areas of GSV should have regard for the presence of small, site-associated species such as the Frayed-Fin Goby. Sheltered seagrass and rubble habitats in the intertidal and shallow subtidal may be particularly important habitats for this species, and planning and management authorities should ensure that measures are in place to avoid further degradation of such habitats.