© 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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Spotted Flounder

Family Name:	Pleuronectidae
Scientific Name:	Ammotretis lituratus (Richardson, 1843)
Recommended Status in S.A:	Data Deficient
Rationale:  The species is included here because A. lituratus (i) S.A. is the edge of the geographic range, and to date there are few records known in this State, from a limited geographical area (gulfs region); (ii) is a site-associated benthic fish species in upper and mid continental shelf waters, and may thus be vulnerable to site-specific impacts in some areas; (iii) has been recorded as a minor component of prawn and fish trawl catches in various parts of the range (with no species-specific data for S.A.), but there is little indication of the total commercial and recreational catch of this species, nor any data on potential impacts; (iv) there is little existing information about the relative abundance, biology and population dynamics of this species across its range.

Page Contents

Current Conservation Status

(No listings known)
 

Distribution

Southern Australia

The species has been recorded in New South Wales, Victoria, Tasmania and Bass Strait islands (Edgar, 1984, 1991, cited by RPDC Marine, 2002), and South Australia (CSIRO Marine Research records, in the Australian National Fish Collection; Museum of Victoria records, South Australian Museum records, cited in OZCAM database, 2007).
A. lituratus is listed as an indicator species for the Tasmanian Province (IMCRA Technical Group, 1996).
Western limit may be eastern Great Australian Bight (M. Gomon, Museum of Victoria, pers. comm., 2007).
 

South Australia

There are few published records of the species in South Australia. Examples of locations where A. lituratus has been recorded include Anxious Bay and Venus Bay (SA Museum records, cited by M. Gomon, pers. comm., 2007); south-eastern and southern Spencer Gulf (BMNH record, 1925; Gomon, in Gomon et al., 1994; Currie and Sorokin, 2010), and various locations in eastern GSV, such as the Port River, and Sellicks Beach, in the southern metropolitan area (S.A. Museum records, cited in OZCAM database, 2008).
 

Habitat

Spotted Flounder have been recorded inshore off beaches, and other sandy bottoms in continental shelf waters (May and Maxwell, 1986; Gomon, in Gomon et al., 1994). In Tasmania, A. lituratus has been recorded from unvegetated bottom in the shallow subtidal, in various beach habitats associated with bays and estuaries around the State (Jordan et al., 1998).
Although in some parts of the range this species was previously known mainly from a narrow depth range (i.e. between 40m and 80m, according to Gomon, in Gomon et al., 1994), it is commonly recorded in shallow waters on sand in Tasmanian estuaries, less than 1m deep. In Tasmania it is also common in beach seine hauls from wading depth (G. Edgar, TAFI, pers. comm., 2007). There are various other examples of specimens from the shallow subtidal. In 2005, a specimen of A. lituratus was recorded in water 1.5m deep, at Queenscliff Beach in Victoria (Museum of Victoria record, identified by M. Gomon, cited in OZCAM database, 2008). Other specimens taken from shallow waters (e.g. from coastal lakes, estuaries and beaches) are also housed by the Museum of Victoria, and Australian Museum. One of the shallowest records to date is 0.5m, being two specimens taken in 1996, from Fisheries Beach at Eden (N.S.W.) (CSIRO record, Australian National Fish Collection, cited in OZCAM database, 2008).  
 

Notes on the Biology

Growth

A. lituratus grows to at least 23cm (Gomon, in Gomon et al., 1994). One of the maximum sizes recorded was 0.580kg, a specimen taken from Green Cape in N.S.W. in 1980 (Australian underwater Federation Inc., 2003).

Diet

During a survey in Spencer Gulf, the gut contents of 2 specimens were examined, and found to contain about 68% small crustaceans (unspecified); 17% gammarid crustaceans, and 14% isopod crustaceans (Currie and Sorokin, 2010).

Reproduction

Flounders live on the sea floor, but are pelagic spawners (Nelson, 2006).
 

Fisheries Information

Commercial

Little species-specific commercial fishing data are available. However, it is noted that flounder species (unspecified) are taken in minor quantities by commercial fishers in southern Australian States (see section above, on Commercial Fishing for flounders as a group).
Ammotretis species are taken commercially in southern Australia. The marketing name for Ammotretis species (including A. lituratus) is “Bay Flounder” (Seafood Services Australia, 2003).
The species is reported to be part of the bycatch in the Commonwealth-managed SESSF (Southern and Eastern Scalefish and Shark Fisheries) (AFMA, 2002a). The species is part of the bycatch in the South East Trawl Fishery (Wayte et al., 2004; Bromhead and Bolton, 2005). For example, in the otter trawl sub-fishery of the SETF, an Integrated Scientific Monitoring Program (ISMP) reported that in 10 trawl shots, 25kg of A. lituratus specimens were retained, and about 2.8kg were discarded (Wayte et al., 2004). In the Danish seine sub-fishery of the SETF, the ISMP recorded 1kg retained in 1 shot, and none discarded.
A. lituratus is a commercial species in Tasmania (Jordan et al., 1998), but species-specific catch data are not available for this report. 
Previously, Spotted Flounder was a minor part of the bycatch in the Bass Strait Central Zone Scallop Fishery. In 2001, 1 specimen of A. lituratus was recorded in the bycatch of 35 random tows (Haddon and Semmens, 2001), and in 2004, 1 was recorded in the bycatch of 36 random tows (Haddon et al., 2004). This fishery has a zero TAC for 3 years from the start of 2006 (so is currently closed) (J. Pogonoski, pers. comm., 2007).
A. lituratus has not been listed as part of the bycatch in the prawn trawl fishery in S.A., but it is noted that at least 6 other flounder species of similar habitat are caught as bycatch in the Spencer Gulf prawn trawl fishery (e.g. Carrick, 1997), and Spotted Flounder was recorded from 6 sites in southern Spencer Gulf during an otter trawl survey in 2007 (Currie and Sorokin, 2010) including some locations periodically worked by prawn trawlers. Given the geographic and depth range and habitat preference of this species, it is possible that Spotted Flounder is caught in prawn trawls in GSV, Investigator Strait and Spencer Gulf, and possible also in the eastern Great Australian Bight, but is unrecorded due to lack of species-specific bycatch statistics. 
When caught in the bycatch of the South Australian Rock Lobster fishery, flounders are permitted to be retained for sale (Sloan, 20003a).
 

Recreational

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.
A. lituratus is taken by recreational fishers in Tasmania (Jordan et al., 1998). In Tasmania, there is a minimum legal size of 25cm for all flounder species taken by recreational fishers (Morton et al., 2005) and there is a personal possession limit of 30 (DPIW Tasmania, 2008). The estimated 21t recreational catch of flounder (all species) in 2000/01 was double the size of the commercial catch, indicating the importance of recreational fishing on this species (Henry and Lyle 2003, cited by Lyle et al., 2004).
In N.S.W., larger flounder species are caught by recreational fishers. The total recreational catch of flounder (species combined) in N.S.W. was estimated to be about 5t per annum during the early and mid 2000s (N.S.W. DPI, 2004). One of the record sizes of A. lituratus was reported to have been taken by spear-fishing in New South Wales (Australian Underwater Federation Inc., 2003).
In Victoria, the minimum legal size is 23cm, for all flounder species taken by recreational fishers, with a bag limit / possession limit of 20 flounder (DPI Victoria, 2007b).
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., there is a legal minimum size of 25cm for all flounder species, and a combined daily bag limit of 8 flathead and flounder (all species) in the West Coast, Gascoyne and South Coast regions (Department of Fisheries, 2007c, 2008a, 2008b).
 

Vulnerable Characteristics of the Species and Threatening Processes

Spotted Flounder might have a geographically limited distribution in S.A., with current records known mainly from the Gulfs region and surrounds.
Benthic fishes in general have limited mobility, more localised reproduction than most pelagic species, and more limited opportunity for population dispersal, all of which can increase the vulnerability of populations to decline.
In a draft ecological risk assessment report for the South East Trawl Fishery (Wayte et al. 2004), 3 “productivity attributes” and 6 “susceptibility attributes” were used to classify A. lituratus as being a “medium risk” species in terms of potential population impacts from trawling.
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). 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 (see below, on Research Recommendations). It is noted, however, that one previous study reported no specimens of A. lituratus  in the prawn trawl bycatch in Spencer Gulf (i.e. Carrick, 1997), and in a more recent trawl survey, this species was recorded in low numbers in south-eastern Spencer Gulf (Currie and Sorokin, 2010), including grounds worked by trawlers, but also grounds not trawled. Therefore, the threat of impact on this species from trawling may be low, at least for that gulf. 
Tanner (2003 and 2005) discussed the impacts of prawn trawling on habitats and benthos in Gulf St Vincent and Investigator Strait, and the species has been recorded in that area.     
A. lituratus occurs in relatively shallow waters, including estuarine areas, and may be susceptible to population impacts due to decline in estuarine habitat and water quality, but there are no species-specific data. 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). There are few pristine or near pristine estuaries remaining in South Australia, and most are subject to numerous impacts (see Bucher and Saenger, 1989; Lewis et al., 1998; Barnett, 2001; GeoScience Australia, 2001; Baker, 2004; Gillanders et al., 2008).
Other than for R. tapiria (see synopsis), there are few specific studies on the impacts of pollutants on flounders in Australia, but it is noted that in the northern hemisphere, sub-lethal effects of sediment contamination (from municipal sources such as  sewage; also industrial pollutants, and other contaminants such as tri-butyl tin from ship and boat anti-foulants) have been recorded. Impacts upon flounders from contaminants include changes in body chemistry, hepatic and other lesions, and reproductive impairment (e.g. Johnson et al., 1993; Myers et al., 1998; CSTEE, 1999; WWF, 1999; Rice et al., 2000).
 

Research Recommendations

More information is required on the current geographical distribution, habitat requirements and depth range of Spotted Flounder in S.A.. The species is little known in this State, with few published records.
There is very little information on the population sizes / relative abundance, biology, and population dynamics of this species.  
There is little indication of the total commercial and recreational catch of this species, in relation to its relative abundance and distribution, including South Australia.
Where possible, prawn trawling bycatch data from Gulf St Vincent, Spencer Gulf and eastern Great Australian Bight (the possible western range limit of this species) should be recorded, analysed and monitored to determine the presence and relative abundance of this (and other less common) flounder species over time. 
 

Management Recommendations

Documentation and quantification of flounder bycatch in fisheries across the geographic range is required.
Assessment of the sustainability of fishing this species commercially (e.g. Tasmania) is required.
As indicated in Research Requirements above, in S.A. a system should be developed for the ongoing collection and monitoring of bycatch data from the Gulf St Vincent 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).
Measures (such as improvements in net design) to reduce the bycatch of benthic fish species in all trawl fisheries should be implemented (see Management Notes, below).
Further recreational fishing controls (e.g. legal minimum sizes, and possession limits) are required in areas where these do not yet exist, and enforcement is also required.
Generally required is the ongoing management and mitigation of the multiple impacts that have reduced the quality of estuarine habitats in S.A. and other southern States. This includes protection of shallow coastal bays from land-based discharges, and, where possible, from coastal activities (such as dredging, and aquaculture developments) that can reduce benthic habitat quality in such bays. 
 

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.