© 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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Butterfly Perch

Family Name:	Serranidae
Scientific Name:	Caesioperca lepidoptera (Forster, in Bloch and Schneider, 1801)
Recommended Status in S.A:	Data Deficient, possibly Least Concern
Rationale:  Butterfly Perch is included here because it (i) is an aggregating species that is strongly site-associated with reefs, and both characteristics can increase the vulnerability of the species to capture; (ii) is a member of the Serranidae, whose life history characteristics make them susceptible to over-exploitation and population decline; (iii) is caught by commercial and recreational fishing in various parts of the range, with few controls over the numbers taken. There is inadequate information to assess the conservation status of this species in South Australia; however the Butterfly Perch may be of Least Concern, due to its broad geographic range and broad depth range, coupled with the likelihood that fishing (which may be the main threatening process) is heavier in other parts of the range, such as Tasmania, compared with South Australia.

Page Contents

Current Conservation Status

No listings known

Distribution

General

In general, Butterfly Perch C. lepidoptera occur across south-eastern and southern Australia (including Tasmania and Bass Strait islands), and around the northern and southern islands of New Zealand (Paxton et al., 1989; Paulin et al., 1989, cited in Froese and Pauly, 2004; Francis, 1996; Barrett and Wilcox, 2001; CSIRO et al., 2001). The species is considered abundant on the coastal reefs of Victoria and Tasmania, particularly those adjacent to deeper water (Hutchins and Swainston, 2001; Edmunds and Hart, 2003). Barrett and Wilcox (2001) reported that C. lepidoptera is particularly abundant below 15m, on reefs in north-eastern Tasmania. Butterfly Perch occurs in lesser numbers on deeper coastal reefs in N.S.W. and S.A., and rarely in W.A. (Hutchins and Swainston, 2001; OZCAM database records, 2004). 

South Australia

In South Australia, Butterfly Perch appear to be less abundant and widespread than Barber Perch (see synopsis for Caesioperca rasor). Some of the locations where Butterfly Perch have been recorded include islands in the Nuyts Archipelago (e.g. St Francis I.), and the Investigator Group islands in the Eastern Great Australian Bight; Anxious Bay on western Eyre Peninsula; deeper waters south of the tip of Eyre Peninsula and west of Kangaroo Island; the “heel” of Yorke Peninsula; and the southern metropolitan coast (Branden et al., 1986; S. Shepherd and J. Brook, unpubl. survey data, 2002; CSIRO Marine Research records; Australian Museum records, South Australian Museum records, Museum of Victoria records, cited in OZCAM database, 2004). It is noted that, other than the more recent survey records from the Nuyts Archipelago and Investigator Group, most of the ‘forementioned records (particularly those from Eyre Peninsula and the Gulfs area of South Australia) are old records, from the early decades of the 1900s.

Habitat

Butterfly Perch is found on reefs in moderately deep waters on the continental shelf (Gomon et al., 1994; Edgar, 2000; Froese and Pauly, 2005).
The reported depth range of Butterfly Perch C. lepidoptera is 10m – 140m (May and Maxwell, 1986, cited by Froese and Pauly, 2005), or 4m – 100m (Edgar, 2000), but the species occurs more often in waters 50m – 100m (Gomon et al., 1994; Kuiter, 1996a). C. lepidoptera is a schooling species over rocky reefs, ledges, and “drop-offs” and usually occurs in areas which are exposed to continual strong tidal water movement (Russell, 1983; May and Maxwell, 1986, cited in Froese and Pauly, 2005).
At a number of sub-maximally exposed reefs in northern and north-eastern Tasmania, Butterfly Perch have been recorded as shallow as 5m – 10m, and are considered to be particularly abundant at depths below 15m (Barrett and Wilcox, 2001). In such habitats, the species has been recorded on reefs with macroalgae cover such as Ecklonia radiata, and Phyllospora comosa, interspersed with barren areas caused by grazing of the urchin Centrostephanus rodgersii (Barrett and Wilcox, 2001). At the Kent Group, Butterfly Perch have been recorded as very abundant in such “urchin barrens” habitat in which macroalgae are depauperate, and sponges are plentiful (RPDC, 2002).  
Juvenile Butterfly Perch sometimes enter shallow bays, particularly in the southern part of the range, and adults are also occasionally seen in shallow water (Kuiter, 1996a).
Butterfly Perch usually occurs in deeper waters than Barber Perch; however mixed schools of both species are occasionally seen off deep “drop-offs” (Kuiter, in Gomon et al., 1994). 
In Victoria, Butterfly Perch occur above “rocky outcrops”, deeper reefs (including “walls” and pinnacles) and sponge “gardens”. In some areas, such habitats are dominated by large sponges, gorgonian corals such as sea fans and sea whips, various coloured bryozoans, soft corals, hydroids, and solitary ascidians (sea tulips), amongst other sessile fauna. In some of these areas, schools of Barber Perch also occur, particularly in shallower water (Parks Victoria, 2004). Also in south-eastern and north-eastern Tasmania, schools of Butterfly Perch have been recorded over reefs dominated by sessile invertebrates such as finger sponges, basket sponges, fan sponges and sea whips (Eaglehawk Dive Centre web site, 2002; Bicheno Dive Centre web site, 2004). Similarly in New Zealand, schools of Butterfly Perch occur over reefs dominated by sessile fauna, with examples including pinnacle reef covered with sponges and bryozoans (Abbott, undated), and reefs covered with gorgonian corals and crinoids (Skipworth, 2002).
Butterfly Perch is also reported to be a common inhabitant of the Giant Kelp (Macrocystis pyrifera) “forests” in Tasmania (uncited reference, in Edyvane, 2003). 
Butterfly Perch has also been recorded around shipwrecks in coastal waters (e.g. the Nord Wreck in southern Tasmania, at 40+m deep – see Calgary Aquarium Society, 1999, and a wreck at Beware Reef in Victoria – see Parks Victoria, 2003).
In N.S.W., the species is usually associated with reefs deeper than 30m (Edgar, 2000).  

Notes on the Biology

Growth

C. lepidoptera grows to about 47cm (Kuiter, in Gomon et al., 1994; Hutchins and Swainston, 2001), but is more often seen at about 30cm (Kuiter, 1996a). To date, the published maximum size of Butterfly Perch is 1.417kg, being a specimen caught in N.S.W., in 1972 (Hutchins and Swainston, 2001; New South Wales Fishing Clubs Association, 2003).

Diet and Feeding Behaviour

Adult Butterfly Perch form large aggregates in deeper water, where they feed mostly in the lower part of the water column, on zooplankton (Russell, 1983, cited in Froese and Pauly, 2006). Butterfly Perch are opportunistic feeders that utilise eddies that swirl zooplankton into concentrations (Parks Victoria, 2004). The large schools of these fish can cloud the water column when they are feeding on zooplankton (Kuiter, 1996a).

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 Caesioperca 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).

Other Information

Butterfly Perch sleep at night in shallow depressions and rock crevices in the reef (Edgar, 2000; Parks Victoria, 2004).

Fisheries Information

Southern Australia

Although the Butterfly Perch is not often taken at a large size, the flesh is considered “quite edible” (Kuiter, in Gomon et al., 1994). Hutchins and Swainston (1986, 2001) also listed the species as being “good eating”.
Butterfly Perch are taken as by-product 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 28 trawl shots, about 125kg of C. lepidoptera was retained and 4kg discarded (Wayte et al., 2004). In the Danish seine sub-fishery, about 8kg of C. lepidoptera are discarded per 5 shots (Wayte et al., 2004).
Butterfly Perch are highly vulnerable to capture using 2-inch gillnets, with previous experiments recording 1,420 (SE 749) individuals caught per 1000 km-hours using that gear (Walker et al., 2003); however it is noted that gillnets of 2-inch mesh size are not used in the shark fisheries in southern Australia.
Butterfly Perch is reported to be part of the discarded bycatch in the Great Australian Bight (GAB) Trawl fishery (Bromhead and Bolton, 2005); however no data are available for this report, and it is noted that the species was not reported in the list of bycatch species, during an Integrated Scientific Monitoring Program for the GAB trawl fishery (Brown and Knuckey, 2002). .
Butterfly Perch is a very minor bycatch species in the N.S.W. Ocean Prawn Trawl Fishery (shelf sector), with a recorded frequency of occurrence of 0.3% in trawl shots (N.S.W. Department of Primary Industries, 2004).
In a study of bycatch in the Tasmanian Rock Lobster fishery, 18,302 rock lobster pots (without escape gaps) were examined between 1992 and 1997. During that period, 51 Butterfly Perch were caught (i.e. an estimate of 359 pot-lifts required for the capture of 1 animal) (Frusher and Gibson, 1998, cited by Ford, 2001. The study also showed that lobster pots with escape gaps can significantly reduce the number of Butterfly Perch caught (Frusher and Gibson, 1998, cited by Ford, 2001).
Butterfly Perch is a very minor part of the bycatch in the Bass Strait Central Zone Scallop Fishery (e.g. Haddon and Semmens, 2002).
C. lepidoptera is sold in the aquarium market, and collected in Tasmania for that purpose. The permitted total annual catch limit is 1000 individuals, with a fishing block limit (6 x 6 nautical miles) of 100 individuals (DPIWE Tasmania, 2005b; Australian Government DEH, 2005b). 

Recreational

Butterfly Perch is taken by recreational fishers. When schooling, smaller specimens are sometimes caught in large numbers, but not always retained. Some clubs and associations keep records of the maximum sizes caught (e.g. Australian Anglers Association Inc. - W.A. Division, 2002a; New South Wales Fishing Clubs Association, 2003; Australian Anglers Association Inc. – Victorian Division, 2003; Fishing Net NZ, 2003). The species is also taken by spear fishers in southern Australia (e.g. see Australian Underwater Federation Inc., 2003). Some charter boat trips in southern Australia also take Butterfly Perch.
There are no specific size or bag limits for Butterfly Perch taken by recreational fishers, including South Australia.
In New Zealand, the Butterfly Perch is promoted as a species for angling and spearfishing, and some clubs and associations keep records of the maximum sizes caught. One spearfishing record came from Stewart Island in 1971 (a specimen of 1.14kg) (New Zealand Underwater Open Spearfishing Records, cited by Bakker, 2004). 

Other

In New Zealand, the Butterfly Perch is one of the species listed as being significant for Maori traditional fishing (Waitangi Tribunal web site, Government of N.Z., 2004).  

Vulnerable Characteristics of the Species

Butterfly Perch is a schooling species, with adults aggregating over reefs, and this behaviour may increase the vulnerability of populations in some areas to over-exploitation.
Butterfly Perch is a member of the Serranidae, a family of fishes whose life history characteristics 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 depletion by a number of fishing methods. However, it is noted that in a recent draft ecological risk assessment of the South East Trawl and Danish Seine Fishery (Wayte et al., 2004), which used 5 “productivity attributes” and 6 “attributes of susceptibility”, Butterfly Perch was  classified as a “low risk” species in terms of population impacts from trawling.

Threatening Processes

Fishing and collecting are likely to be the main threatening processes. In deeper waters, the species is taken as by-product in some fisheries and discarded as bycatch in others. In shallow water it is caught by recreational fishers, and collected for the aquarium trade.

Research Requirements

More data are required on the biology, demography and population dynamics of this species.
Assessment is required of the potential effects of fishing on Butterfly Perch population abundance and structure. 

Management Requirements

Given the vulnerability of Serranids to population declines, restrictions on the commercial and recreational take of this species are recommended, particularly the targeting of aggregations. Currently, there are inadequate catch restrictions in all States.
Where possible, measures to reduce the bycatch of Butterfly Perch in commercial fisheries should be implemented, at both State and Commonwealth level. 
The numbers taken for the aquarium trade should be monitored, and the potential for localised population impacts should be assessed.
Marine protected areas are beneficial for conserving populations of site-associated species such as Serranids, and due consideration should be given to the formal protection of some areas (in S.A.) which this species occurs.

Other Information

Butterfly Perch and/or Barber Perch occur in a number of marine parks and reserves in Victoria, such as Wilsons Promontory, Bunurong, Port Phillip Heads (including Portsea Hole), Phillip Island and Point Hicks Marine National Parks, and Beware Reef Marine Sanctuary (Wilson et al, 1983; Turner and Norman, 1998; Edmunds e al., 2003; Plummer et al., 2003; Melbourne University Underwater Club web site, 2004; Parks Victoria, 2004).
The Butterfly Perch occurs in a number of sanctuary areas in New Zealand, such as the Poor Knights Islands Marine Reserve; Te Tapuwae O Rongokako Marine Reserve, and Tuhua (Mayor Island) Marine Reserve.
Butterfly Perch are found in the Maria Island Marine Reserve in Tasmania (Parks and Wildlife Service, 1998).
Butterfly Perch is of interest to divers for viewing and photography.