© 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.

---

Slender Orange Perch / Western Sea Perch

Family Name:	Serranidae
Scientific Name:	Lepidoperca occidentalis Whitley, 1951
Recommended Status in S.A:	Data Deficient
Rationale:  The Slender Orange Perch is included here because it (i) has a limited geographic distribution within S.A., with the Great Australian Bight being the eastern edge of the species range; (ii) is a member of the Serranidae, whose life history characteristics make them susceptible to over-exploitation and population decline; (iii) is taken as by-product, and discarded as bycatch, in trawl fisheries in deeper waters of the continental shelf, and (iv) there is a paucity of information about relative abundance / population sizes, habitat requirements, biology, and population dynamics.

Page Contents

Current Conservation Status

No listings known

Distribution

General

The species occurs in western South Australia and southern Western Australia (Kuiter, in Gomon et al., 1994). Slender Orange Perch L. occidentalis has also been recorded between the central coast of W.A. and Eyre Peninsula in S.A. (Paxton et al., 1989; Kuiter, in Gomon et al., 1994). Slender Orange Perch is known mostly from the central to southern coast of W.A., and it is from that region that most trawl records and museum records originate.

South Australia

There are few published records of Slender Orange Perch from South Australia, which include museum specimens from the W.A. / S.A. border  (Australian Museum records; Museum of Victoria records, cited in OZCAM, 2006), and an old record (1914) reported to be L. occidentalis, from southern Yorke Peninsula (Australian Museum record, cited in OZCAM database, 2006). 

Habitat

This species is demersal in deeper waters of the continental shelf (Kuiter, in Gomon et al., 1994; Froese and Pauly, 2004). The known depth range of Slender Orange L. occidentalis is 40m – 200m (May and Maxwell, 1986, cited in Froese and Pauly, 2006) or 60m – 200m (Kuiter, in Gomon et al., 1994).

Notes on the Biology

Growth

L. occidentalis grows to more than 20cm (Kuiter, in Gomon et al., 1994).

Diet

No specific information on the diet is available, however it is noted that smaller Serranids usually eat zooplankton (Heemstra and Randall, 1999).

Reproduction

Most species in the Serranidae are protogynous hermaphrodites, as are most members of the sub-family Anthiinae (P. Heemstra, South African Institute for Aquatic Biodiversity, pers. comm., 2006) to which species in Lepidoperca belong. Protogynous hermaphrodites first mature as females and, after spawning one or more times, they will then change sex, spawning thereafter as males (Heemstra and Randall, 1999).

Fisheries Information

L. occidentalis is reportedly part of the bycatch in the Commonwealth-managed SESSF (Southern and Eastern Scalefish and Shark Fisheries) (AFMA, 2002a).  In the otter trawl sub-fishery of the South East Trawl Fishery, an Integrated Scientific Monitoring Program (ISMP) reported that in 32 trawl shots, about 263kg of L. occidentalis was retained and 457kg discarded, which is an average of 8kg retained per trawl shot, and 14kg discarded per trawl shot (Wayte et al., 2004).
In the Great Australian Bight Trawl Fishery, fishers’ logbooks recorded a small catch (200kg) of “Orange Perch” in 2000/01, but the species was not specified. Bromhead and Bolton (2005), listed L. occidentalis as a discarded species in the Great Australian Bight Trawl Fishery, and of uncertain use in the South East Trawl Fishery (i.e. insufficient information to determine whether the species is retained or discarded).
This species is known mainly from trawling records in Western Australia. For example, one or both of the western Lepidoperca species is taken in the Western Trawl Fisheries (which, for reporting purposes, comprises the North West Slope Trawl Fishery and the Western Deepwater Trawl Fishery). During the period 1992/93 to 2003/04, at least 2,287 Orange Perch were taken in the Western Trawl Fisheries, comprising a range of 0 – 735 individuals per annum, and a catch of several hundred specimens per year in some of those years (AFMA, 2004f). Catch data were not included for 5 of the years in the ‘forementioned period, hence the total catch of Lepidoperca would be higher than that specified. It is noted that the logbook data specified above, incorrectly reported the Orange Perch catch as being the eastern species L. pulchella, which does not occur in Western Australia.

Vulnerable Characteristics of the Species

The species is a member of the Serranidae, a family of fish that have life history characteristics that increase the vulnerability of populations to decline. For example, Serranids are generally slow moving, benthic, site-associated fish with distinct population structure, which makes them vulnerable to fishing-induced population impacts (see section above, on Serranidae family).
Slender Orange Perch L. occidentalis is known from few specimens (Gomon et al., 1994). Virtually nothing is known of the distribution within the range, relative abundance, habitat requirements, biology, ecology, or population dynamics of these species.

Threatening Processes

Capture in benthic trawls may be the main threatening process for populations of Lepidoperca species in south-central and south-western Australia. Although there are no species-specific data for Slender Orange Perch, the closely related south-eastern Australian species Lepidoperca pulchella (Orange Perch) has been listed as one of the bycatch species in the N.S.W. Ocean Trawl Fishery that has a “high” fishery impact profile (New South Wales Department of Primary Industries, 2004). Studies in New South Wales showed that the species suffers barotrauma when hauled in trawls, also has a low probability of survival when caught, and L. pulchella was classified overall as an “intermediate to high risk” species in terms of population impacts from trawl fishing. A very similar assessment was given for the N.S.W. species, Lepidoperca brochata (see NSW Department of Primary Industries, 2004).
In a recent draft ecological risk assessment of the South East Trawl and Danish Seine Fishery (Wayte et al., 2004), 5 “productivity attributes” and 6 “attributes of susceptibility” for Slender Orange Perch / Western Sea Perch L. occidentalis were used to categorise it as a “low risk” species; however the overall value was close to the lower end of the range assigned for species of “medium risk” i.e. species that are susceptible to population impacts from trawling.

Research Requirements

For both species of Lepidoperca, data are required on the distribution (within the geographic range and depth range), relative abundance, habitat requirements, biology, ecology, and population dynamics.

Management Requirements

Target catch, by-product and bycatch of this species in trawl fisheries should be better quantified, and monitored over time. Measures are required to reduce the bycatch of this species, particularly in trawl fisheries. 
Given that there is virtually no knowledge of the species relative abundance, biology, habitats, or resilience to exploitation, methods to reduce the bycatch of this species should be investigated.