SERRANIDAE: SEAPERCHES, ROCKCODS AND WIRRAHS
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| (c) R. Stuart-Smith, Reef Life Survey |
Globally, there are more than 500 species in the Serranidae family, including the Groupers, Hinds, Sea Basses, Fairy Basslets, Seaperches, Perchlets, Wirrahs, and others (Froese and Pauly, 2008).
There are at least 159 species in Australian waters, a few of which are yet to be named (CSIRO, 2008). The Serranidae family in southern Australia includes:
• the Wirrah species: there are 3 species in southern Australia, and one of these, the Western Wirrah Acanthistius serratus, occurs in the western part of South Australia as well as W.A.;
• the Caesioperca (“Perch”) species Butterfly Perch and Barber Perch, both of which occur on reefs and around islands in southern Australia, including S.A., and are occasionally taken as commercial bycatch, and also by anglers and spear fishers;
• Lepidoperca species: the Orange Perches, of which 7 are currently recognised in Australia; two of these occur in deeper waters in western South Australia and W.A., and the other 4 in eastern and/or south-eastern Australia, including the most well known Orange Perch Lepidoperca pulchella; the less commonly known N.S.W. endemic species L. brochata, and the endemic Tasmanian species Lepidoperca tasmanica. Some of the eastern species are part of the bycatch in the South East Trawl Fishery, and ocean trawl fisheries in New South Wales;
• Hypoplectrodes species, such as the Spotty Seaperch H. wilsoni and Red Seaperch H. cardinalis (both of which occur only in W.A.), and the Yellow-banded H. annulatus, Black-Banded H. nigrorubrum / H. nigroruber, and the eastern Australian Half-banded Seaperch H. maccullochi;
Black Rockcod Epinephelus daemelii, which occurs mainly in sub-tropical waters of eastern Australia, and is discussed below as a species of conservation concern;
• Epinephelides armatus, the Breaksea Cod, a popular table fish found in south-western Australia; and
• Othos dentex, the Harlequin Fish, from Western Australia and South Australia, which is discussed below.
(Kuiter, in Gomon et al., 1994; Edgar, 2000; AFMA, 2002a; N.S.W. Department of Primary Industries, 2004; Froese and Pauly, 2006; CSIRO, 2008).
Pogonoski et al. (2002, see: http://www.deh.gov.au/coasts/species/marine-fish/serranidae.html) summarised the vulnerable population characteristics of the Serranidae, with particular reference to the Groupers (sub-family Epinephelinae), mainly tropical and sub-tropical species which are highly valued as eating, sports and aquarium fish, and for dive tourism. Many species are at or near the upper end of their food chains, therefore there are usually few residents at any one locality. Individual reefs may only have one or two very large resident groupers, and because these large individuals may be several decades old, it takes a long time for over-fished groupers to be replaced. Due to members of the Serranidae typically being protogynous hermaphrodites (whereby individuals start life as a female and then change sex to reproduce as a male), the larger, rarer males are easily over-fished, and this presents problems for fishery management. Commercial, sports and subsistence fisheries are often biased (by means of hook size and fishing techniques) towards the capture of larger adults, which are usually the males (Heemstra and Randall, 1993; Sadovy, 1997, cited by Pogonoski et al., 2002). Some species may aggregate to spawn at well defined times and locations, which further increases their vulnerability. Groupers differ from many commercially fished species because they are exploited in a wide variety of ways and at different phases of their life-history (Pogonoski et al., 2002). In summary, many Serranids appear to be particularly vulnerable to anything other than low levels of fishing pressure due to their slow growth rate, low reproductive rate, long life span, large size at sexual maturation, sex change, and low natural mortality.
The high vulnerability of Serranid fishes to extirpation is reflected in the increasing number of species within the family that are listed internationally in the IUCN Red List of Threatened Species: 37 species in 2004, which increased to 167 species in 2008, including those classified as Data Deficient and Least Concern (IUCN, 2008). Three of these are listed as Critically Endangered and another 5 as Endangered.
Although most Serranids listed as threatened species are from the tropical Indo-Pacific, a number of species extend into sub-tropical and/or temperate waters in the southern half of Australia. Examples of those species that are on the IUCN Red List (IUCN, 2008), include:
• Epinephelus lanceolatus Queensland Grouper: Vulnerable (A2d);
• Epinephelus coioides Estuary Rockcod / Estuary Cod: Near Threatened, with a decreasing population trend; • Epinephelides armatus Breaksea Cod: Near Threatened
A number of tropical Serranids that extend into temperate Australian waters are formally protected under State legislation, including the following:
• Epinephelus lanceolatus Queensland Grouper: protected from capture in W.A. and N.S.W.;
• Epinephelus daemelii Black Rockcod: protected from capture in N.S.W.
• Epinephelus tukula Potato Cod: protected in W.A.
• All members of the Serranidae (e.g. groupers, estuary cod) over 120cm: protected from capture in W.A.
Commercial and Recreational Fishing
The fishing of Serranidae in tropical parts of Australia will not be discussed here. In southern Australia, there are fewer Serranids that are important target species, compared with the tropical Indo-Pacific region. Examples of Serranids taken commercially and/or recreationally in parts of temperate Australia include Breaksea Cod Epinephelides armatus (W.A. only), Harlequin Fish Othos dentex (particularly in W.A. but also in S.A., and discussed below as a species of conservation concern), and the Long-finned Perch Caprodon longimanus (a widespread Pacific species, fished in N.S.W.). As table fish, the seaperches (Hypoplectrodes), wirrahs (Acanthistius) and perches (Caesioperca) are less highly regarded than the groupers (e.g. Epinephelus, Epinephelides). A number of tropical groupers extend along the south-eastern or south-western coasts of Australia, and are popular targets for fishers. These include, amongst others:Chinaman Rockcod Epinephelus rivulatus: About 6.4t and 9t were taken commercially in W.A., in 2002/03 and 2003/04 respectively (Department of Fisheries, W.A., 2004f, 2005c). About 28,800 individuals were taken by recreational fishers in W.A. in 2000-01 (Henry and Lyle, 2003), including sub-tropical waters.
Estuary Rockcod Epinephelus coioides, a near threatened tropical species (according to IUCN) which extends southwards into W.A. and N.S.W.. It is notable that no commercial catch statistics are listed for this species in W.A. (e.g. Department of Fisheries, W.A., 2004f, 2005c); other than the take of Estuary Rockcod in that State for the aquarium trade (with an average of 172 specimens per annum taken during the period 2000 – 2003) (Department of Fisheries, W.A., 2004b). About 9,530 and 1,060 Estuary Cod specimens were taken by recreational fishers in W.A. and N.S.W. respectively, in 2000-01 (Henry and Lyle, 2003);
Banded Rockcod Epinephelus ergastularius, a deep water species which extends south into New South Wales. It has been heavily targeted by commercial line fishers, and is also taken as bycatch in several other fisheries in eastern Australia (Pogonoski et al., 2002);
Blacktip Rockcod Epinephelus fasciatus, a widespread Indo-Pacific species that extends south into N.S.W. in the east, and south-western W.A. in the west. It is fished commercially along much of the Australian coast, including central and southern W.A. and New South Wales (e.g. FRDC, 2005);
Eightbar Grouper (Grey-banded Rockcod) Epinephelus octofasciatus, of which 27t and 59.6t were taken commercially in W.A., in 2002/03 and 2003/04 respectively, according to Department of Fisheries, W.A. (2004f, 2005c).
Previously, the Black Rockcod Epinephelus daemelii was a highly sought after species in eastern Australia, particularly by anglers and spear fishers, but is now protected in N.S.W. due to its depleted status from over-fishing (see synopsis below).
Of note in a discussion of fishing for temperate Serranids is the Breaksea Cod, a large (> 50 cm), slow to mature (3–4 years), long-lived (> 20 years), reef-associated grouper from inshore waters in Western Australia. Breaksea Cod is taken by commercial and (especially) recreational fishers in W.A., with commercial catches in the order of 8 – 10t per annum, during the period 2002 - 2006 (Department of Fisheries, W.A., 2004f, 2005c; Fletcher and Santoro, 2007), and recreational catches during 2000-01 of about 50,700 individuals (Henry and Lyle, 2003). Breaksea Cod is a popular species for recreational fishing in W.A., and is a common component of mixed catches from hook-and-line over inshore reefs (Prokop, 2002, cited by Cornish, 2004). Although there is a bag limit for recreational fishing, larger individuals have apparently been depleted in inshore areas (particularly the metropolitan area), and fishers are consequently moving further offshore to target the larger specimens (Stagles, 2005). Vulnerable population characteristics include the limited spatial distribution, association with nearshore habitats, large size, inquisitive nature, ease of capture, vulnerability of all age classes to capture (ranging from young, sexually immature fish, to the largest, oldest adults), low reproductive potential, and probable low survival rate of released specimens that are under legal size (Eastman, 2001; J. St John, W.A. Fisheries, pers. comm. 2003, cited by Cornish, 2004; Stagles, 2005). IUCN classified the species as being Near Threatened (Cornish, 2004), and recommended that the status be re-assessed at regular intervals, in light of the vulnerable population characteristics, the significant increase in recreational fishing in W.A. in recent years, and the inadequate controls on the take by commercial fishers.
Although catch and effort statistics are collated for some of the more commonly targeted species, significant quantities of unspecified Serranids are taken annually in commercial fisheries. For example, about 80 to 84 t per annum of unspecified “cod” in the Serranidae were taken commercially in W.A. between 2004 and 2004, and 64 t in 2005-06 (Department of Fisheries, W.A., 2004f and 2005c; Fletcher and Santoro, 2007). Similarly for recreational fishing, marine “perch” and “cod” species are often not recorded to species level in catch statistics. For example, the National Recreational and Indigenous Fishing Survey (Henry and Lyle, 2003) reported that about 20,000 and 10,770 “perch – (marine) unspecified” specimens were caught and kept by recreational fishers in South Australia and W.A. respectively, during the survey time period (May 2000 to April 2001), and a proportion of those were likely to have been Serranids. In W.A. during that period, 36,580 “coral trout – unspecified” fish and 54,521 “cod – unspecified” were taken, with similarly high numbers in Tasmania (68,575 “cod – unspecified”). As noted by Heemstra and Randall (1993, cited by Pogonoski et al., 2002), although it is difficult to identify some of the members of this family, fisheries for Serranids could be better managed, and the stocks better conserved, if the species were separated in catch statistics and other fishing reports, rather than summarising landings by family or common names.
Due to the strong reef association, large size and slow movements of many species in the Serranidae, they are usually highly vulnerable to capture by spear fishers. Some of the record-sized specimens of various Serranid species in Australia have been taken by spear fishing (e.g. Australian Underwater Federation Inc., 2003).
In addition to target commercial and recreational fishing, various Serranids in southern Australia are caught as bycatch in a number of fisheries at Commonwealth level (e.g. AFMA, 2002a, and Walker et al., 2003) and State levels (e.g. Pogonoski et al., 2002; Haddon and Semmens, 2002; Sloan, 2003a). When taken as bycatch, Serranids are not usually separated by species, particularly when they are not caught in significant numbers. For example, in the Northern Zone Rock Lobster fishery in South Australia, a sampling of 32,000 pots in 1991 – 1992, showed that during that period, 22 Serranids (unspecified) were caught in 10 pots during the bycatch sampling program (Prescott, 2001). For the Southern Zone (21,000 pots sampled), 50 Serranids were reportedly caught in 50 pots during the 1991-92 season (Prescott, 2001).
The Serranids that occur in South Australian waters are discussed below. None of the species is endemic within S.A. waters, but all are included here due to the vulnerable characteristics of fish in the Serranidae, coupled with the fact that most are edible and thus fished commercially and/or recreationally, with few controls on the numbers taken.
Associated taxa
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