© 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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Small-eye Flounder / Smalleye Flounder / Flimsy Flounder

Family Name:	Bothidae
Scientific Name:	Arnoglossus micrommatus Amaoka, Arai and Gomon, 1997
Recommended Status in S.A:	Data Deficient
Rationale:  Arnoglossus micrommatus is included here because it (i) is a little known species, with few published records; (ii) has a limited distribution in S.A. which is at the eastern edge of the geographic range; (iii) occurs in coastal areas such as the eastern Great Australian Bight, where it is known to be a bycatch of prawn trawling; however, bycatch species identification and quantification are insufficient in the S.A. prawn fishery in the eastern GAB, hence the previous and current extent of capture of Smalleye / Flimsy Flounder in prawn trawls in S.A. is not known, and no assessment of potential population impacts has been undertaken; and (iv) little in known of the full distribution, depth range, biology or population dynamics of this species.

Page Contents

Current Conservation Status

(No listings known)

Distribution

Small-eye Flounder / Flimsy Flounder occurs along the south coast of Australia, with records from south-western Australia (e.g. Albany, King George Sound as far north as Perth) and western Great Australian Bight, and the Anxious Bay area in eastern Great Australian Bight, and in Investigator Strait (e.g. north of Emu Bay, Kangaroo I.) (Gomon, in Gomon et al., 1994; W.A. Museum records; S.A. Museum records, 1981 and 1982, identified by Masahito Arai, 1995, cited by R. Foster, pers. comm., 2006; M. Gomon, Museum of Victoria, pers. comm., 2007).

Habitat

The species occurs in sandy areas, from about 5m to 60m deep (Amaoka et al., 1997, cited in Froese and Pauly, 2008). In S.A., the species has mainly been recorded in recorded at depths from ~ 33m (South Australian Museum record) to ~ 60m (Gomon, in Gomon et al., 1994), in trawl grounds (S.A. Museum records, cited by R. Foster, pers. comm., 2006). The full depth range is not known.

Notes on the Biology

The species grows to ~ 13cm SL (Amaoka et al., 1997), or 17cm total length (as “Arnoglossus sp.”, in Gomon, in Gomon et al., 1994).
Flounders live on the sea floor, but are pelagic spawners (Nelson, 2006).

Fisheries Information

Commercial

The Small-eye Flounder / Flimsy Flounder has been recorded as prawn trawl bycatch in the eastern Great Australian Bight (Gomon, in Gomon et al., 1994), and in Investigator Strait (South Australian Museum records, 1981 and 1982, identified by Masahito Arai, 1995, cited by R. Foster, pers. comm., 2006). Quantitative bycatch data are not available (see Management Requirements, below).
For flounders, no species-specific commercial fishing data are available for this report. Commercial catches are likely to be low, given the restricted distribution of this species.
When caught in the bycatch of the South Australian Rock Lobster fishery, flounders are permitted to be retained for sale (Sloan, 20003a).
 

Recreational

Recreational catches of this species are not quantified. Recreational catches are likely to be low, given the apparently restricted distribution of this species.
Recreational survey catch statistics (e.g. Henry and Lyle, 2003) group recreational catches of flounders with soles and other flatfish, and summary statistics, as well as other State-level data, are provided in the section on Recreational Fishing, at the beginning of this chapter.
For recreational fishers in South Australia, there is a daily bag limit of 20 flounder (all species) and a boat limit of 60. There is no legal minimum size (PIRSA, 2008a, 2008b).  
In W.A., the legal minimum size is 25cm for all flounder species. There is a combined daily bag limit of 8 flathead and flounder (all species) in the South Coast region (Department of Fisheries, 2008b).
 

Vulnerable Characteristics of the Species and Threatening Processes

The full distribution and depth range of this species are not known. If the Smalleye Flounder / Flimsy Flounder is restricted to the depth range and geographical area in which it has been found to date, it might, intrinsically, be vulnerable to population decline due to its geographically limited distribution, and presence in an area of S.A. with an ongoing threatening process (prawn trawling).
Benthic fishes in general have limited mobility, more localised reproduction than most pelagic species, and limited opportunity for population dispersal, all of which can increase the vulnerability of populations to decline.
Flounder species in general are defined as “Category 2” fish in W.A., with a “medium risk” of over-exploitation. Category 2 fish species generally mature at two to three years old, are of moderate abundance, are highly targeted, and/or often utilise estuarine and inshore habitats extensively (Department of Fisheries, 2004).
Flounders are vulnerable to capture in prawn trawls, due to their benthic nature, existence in the same habitats as prawns are found, and their poor swimming ability (Carrick, 1997; PIRSA, 2003). The species is known from prawn trawling grounds (Gomon, in Gomon et al., 1994; South Australian Museum data), but there is no quantitative information on the capture of this species by prawn trawlers in the eastern Great Australian Bight (West Coast prawn fishery) or in Investigator Strait (Gulf St Vincent prawn fishery). Mortality due to trawling may be a threatening process for some of the flounder species of lesser abundance in S.A., but no species-specific data are available.
Tanner (2003 and 2005) discussed the impacts of prawn trawling on habitats and benthos in Gulf St Vincent, and flounders live in such trawled habitat.
 

Research Requirements

The full geographic distribution and depth range of Small-eye Flounder are not known, because so few specimens have been recorded to date. The S.A. Museum houses four identified records (as Arnoglossus sp.), all collected by trawl in 1981 and 1982. It is possible that others exist in the collection, but they have not been identified to date (2008).
Skilled observers are required to record bycatch of this species in trawl fisheries in S.A., particularly GSV and the eastern GAB. Given the currently known depth range, and the fact that the species has been recorded in trawl grounds in Investigator Strait (central S.A.) and eastern GAB (western S.A.), it is possible that this species also occurs in the deepest parts of the Spencer Gulf trawl grounds, but has been misidentified (as another Arnoglossus species) during bycatch survey in the 1990s and early 2000s.   
 

Management Requirements

In S.A., a system should be developed for the ongoing collection and monitoring of bycatch data from the GSV Prawn Fishery and the West Coast Prawn Fishery (as currently occurs in the Spencer Gulf Prawn Trawl Fishery), sufficient to enable identification of long-term trends in bycatch (Australian Government DEH, 2004b; Dixon et al., 2005). In particular, data on species of apparent limited geographic range (such as Small-eye / Flimsy Flounder) should be recorded when specimens occur in bycatch.
Measures (such as further improvements in net design) to reduce the bycatch of benthic fish species in all trawl fisheries are recommended.
 

Management Notes

It is noted that prawn fisheries in southern Australia have made significant efforts during the past decades to reduce the bycatch of finfish species. Examples for Spencer Gulf and Gulf St Vincent include the spatial and temporal organisation and “real time” management of the fishing fleet in some areas (e.g. Spencer Gulf) to minimise capture of undersized prawns and bycatch species, and developments in gear design to reduce bycatch, such as square-mesh cod-ends, bycatch chutes, hopper/conveyor systems, and the fitting of exclusion devices (e.g. MacDonald, 1998; Carrick, 1997; Broadhurst et al., 1999; South Australian Prawn Industry Association web site, 2000; PIRSA, 2003). PIRSA (2003) reported that field studies have indicated that survival of flounders (e.g. the commonly caught species Pseudorhombus jenynsii) is higher with hopper/conveyors systems, compared with the previously used sorting equipment. However, Australian Government DEH (2004b) reported that further work is required to confirm this assumption.