© 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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Harlequin Fish

© J. Brook

Family Name:	Serranidae
Scientific Name:	Othos dentex (Cuvier, 1828)
Recommended Status in S.A:	Near Threatened, should be protected under S.A. Fisheries Management Act 2007, or fishing regulations introduced as a minimum
Rationale:  The species is included here because (i) Harlequin Fish is a southern Australian endemic with a limited geographic distribution (S.A. and W.A.), and a limited known depth range; (ii) it is a site-associated coastal reef fish with vulnerable population characteristics, similar to other species in the Serranidae family. Examples include benthic existence and strong site association with reefs and caves, assumed slow growth, large size, susceptibility to barotrauma, and inquisitive nature/attraction to divers; (iii) there is a paucity of information about population sizes, biology, and population dynamics; (iv) it is likely that the relative abundance of this species in S.A. is much lower than in W.A.; (v) there is concern that abundance may have declined over time in areas where water  quality is reduced, and reefs are degraded; and (vi) Harlequin Fish is caught recreationally and (to a lesser extent) commercially across its range by a number of methods, with few controls on the capture, particularly in S.A., and no investigation of the potential impacts of fishing has been undertaken.

Page Contents

Current Conservation Status

No listings known

Distribution

Southern Australia

The species is reported to be endemic to South Australia and Western Australia (Hutchins and Swainston, 1986; Edgar, 2000); however in Victoria, Harlequin Fish are reported to have previously occurred in Port Phillip Bay (adult specimens collected late 1800s), but the species is considered to no longer occur in the area, possibly because O. dentex prefer clean clear waters, and Port Phillip Bay now has low quality silt-laden water (M. Gomon, Museum of Victoria, 2002).

South Australia

In South Australia, the species is known from numerous reef areas around the state, including the following (compiled from survey, diving and recreational fishing records, cited in Baker, 2004; D. Cowan, unpubl. survey data, 1980 – 2001; D. Muirhead, pers. comm. 2005; Reef Watch, 2006, 2007; Edgar et al., 2006; photograph by A. Burnell, 2008): Encounter Bay; West I. (out of Encounter Bay); southern Fleurieu Peninsula (e.g. Rapid Head, Rapid Bay, Wirrina Reef, Second Valley); southern metropolitan area of Gulf St Vincent (e.g. Port Noarlunga; Aldinga); north-eastern Kangaroo I. / Dudley Peninsula (e.g. Penneshaw, Hog Bay area, Kangaroo Head, Snapper Point, and other locations); northern and north-western Kangaroo I. (particularly the area between Penneshaw and Western River, according to D. Muirhead, MLSSA, pers. comm., 2005); southern Yorke Peninsula (e.g. Corny Point / Point Souttar area; Innes National Park coastal reefs and nearshore islands; coastal reefs between Royston Head and Penguin Point; and islands seaward of the southern Yorke Peninsula, such as Althorpe Is.; Haystack I., Seal I.); Thorny Passage (and islands within Thorny Passage); islands south of Spencer Gulf (e.g. Wedge I., North I. and other islands in the Gambier group); headlands, and bays off southern Eyre Peninsula (i.e. off Coffin Bay Peninsula and Jussieu Peninsula); islands off southern Eyre Peninsula (e.g. Perforated I. – K. Branden and S. Shepherd, unpubl. data, 1987); headlands and exposed bays (e.g. Fowlers Bay), and coastal islands of the eastern Great Australian Bight / western Eyre Peninsula (such as Olive Island, Cape Bauer, other rocky headlands south of Streaky Bay); and offshore islands in the eastern Great Australian Bight (including Nuyts Archipelago; and the Investigator group of islands – the latter including Pearson, Ward, Waldegrave, and others).

Habitat

The species occurs to at least 50m, on moderately exposed coastal rocky reefs, near reef drop-offs, over reef “lumps” (i.e. small rises surrounded by flatter benthic topography, in coastal waters), in caves, and under ledges (May and Maxwell, 1986; Hutchins and Swainston, 1986; Edgar, 2000; S.A. and W.A. recreational fishing and diving reports, 2001-2004; chater boat fishing reports, cited by S. Bryars, dEH, pers. comm., 2008).
During dives over a 20 year period, one recreational diver in S.A. recorded the species at 11 sites, mainly moderate to high energy areas, from 6m to 25m deep, but mainly at depths over 10m (D. Cowan, unpubl. data, 1980 – 2001). 
There are records of the species in the vicinity of shipwrecks that serve as artificial reefs (e.g. Cheynes III, near Michaelmas Island in southern W.A.).

Notes on the Biology

Growth

Harlequin Fish grows to around 75cm - 76cm (Hutchins and Swainston, 1986; Kuiter, in Gomon et al., 1994; Department of Fisheries, Western Australia, 2004).
The species can grow to well over 3kg. Hutchins and Swainston (2001) reported a maximum weight of 5.94kg. One of the maximum weights of a specimen taken by spearfishing is 4.25kg (Australian Underwater Federation Inc., 2003). Another recorded maximum weight of a Harlequin Fish taken by angling is 3.62kg, being a specimen taken from Walpole in W.A., in 1995 (Australian Anglers Association, 2003).
A study to determine the age of harlequin fish using otoliths is currently underway (Simon Bryars, DEH, pers. comm., 2008).

Diet

Harlequin Fish is a “sit-and-wait” ambush predator (S. Shepherd, pers. comm., 2005), that feeds on abalone such as Haliotis ruber (Shepherd, 1973) and various small fish species (Scott et al., 1974; Masuda and Allen, 1993, cited in Froese and Pauly, 2006).

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 Othos dentex belongs. 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).
Anecdotal evidence from divers and fishers suggests that males and females may occur together at times and are of different colouration (Stagles, 2005; S. Bryars, DEH, pers. comm., 2008).

Behaviour

Harlequin fish are often seen resting on the seabed (Edgar 1997).
Harlequin fish are mostly spotted alone by divers. Fishers also usually only catch one or two at each ‘drop’, indicating that fish are solitary and that numbers are naturally low.
Harlequin fish are inquisitive and will follow divers (Edgar 1997).

Fisheries Information

Commonwealth

The species is caught in low numbers in the Southern Shark Fishery (= SSF component of the Commonwealth-managed Gillnet Hook and Trap Fishery). AFMA (2002a) reported that during 2000/01, a total catch of 10 Harlequin Fish was recorded in shot-by-shot logbooks in the SSF. Similarly, gillnet mesh-size experiments reported by Walker et al. (2003) show that Harlequin Fish are catchable in small numbers in the South Australian sector of the Southern Shark Fishery. It is noted however, that during the sampling period in 1973-76, Harlequin Fish (8 specimens) were recorded in 5-inch mesh nets, but not in nets of other mesh sizes. In the SSF fishery, the minimum mesh size is 6 inches (since 1975) and the maximum is 6.5 inches (since 1997) (Independent Allocation Review Panel, 2003). 

Western Australia

In Western Australia, Harlequin Fish is on the list of “Prized Fish” caught by W.A. anglers (see Curnow and Harrison, 2001; Harrison, 2001; Department of Fisheries, 2003b).
A Western Australian Fisheries Department survey, conducted in 1996-1997 in the West Coast Bioregion (between Augusta in the south and Kalbarri on the central coast), reported that up to 1,666 (SE 307) O. dentex fish were kept by recreational boat fishers during that period (Sumner and Williamson, 1999). In the South Coast bioregion, Harlequin Fish are taken by boat fishers further offshore, as part of a mixed catch of large reef fish species (Department of Fisheries, W.A., 2005c, 2005d). The National Recreational and Indigenous Fishing Survey (Henry and Lyle, 2003) estimated that in W.A., 4,697 Harlequin Fish were caught and kept by recreational fishers during the survey period (May 2000 to April 2001).
Angling clubs in W.A. keep records of the largest individuals caught (e.g. AAAI, 2002a and 2002b). 
Harlequin Fish is promoted as a species for spear fishers to catch in Western Australia (Smith, 2000; International Freediving and Spearfishing News, undated). The record size of a Harlequin Fish taken by spearfishing (4.25kg) is reported to have been a specimen caught in 1983, at Augusta, W.A. (Australian Underwater Federation Inc., 2003).
Charter boat companies in some parts of W.A. promote the catching of Harlequin Fish during charter fishing trips (e.g. charters departing from Fremantle and Palm Beach).  In addition to the central west coast / West Coast Bioregion, recreational fishers (and charter boats, in some locations) also take Harlequin Fish along the far south coast of Western Australia (e.g. Augusta, Walpole, Esperance area, islands of the Recherché Archipelago, Bremer Bay) (Reid, 2001; Burns, 2003; Fishing Western Australia, 2004; recreational fishing records, cited by Australian Anglers Association Inc., 2002a and 2002b).
The species is recorded as a minor component of the bycatch in the temperate demersal gillnet and demersal long line fisheries in W.A., and is discarded (McAuley and Simpfendorfer, 2003). 
In shallow inshore waters, lobster pots infrequently catch Harlequin Fish (Department of Fisheries, Western Australia, 2004g).

South Australia

Harlequin Fish, including large adults, are targeted by recreational line fishers and charter boat fishers in various parts of South Australia, such as Southern Yorke Peninsula coastal reefs and nearshore islands; around the coast of Kangaroo Island and Investigator Strait; Althorpe Islands; West Coast headlands, bays, and islands (e.g. Cape Bauer, Olive Island, and other locations in the region) (recreational fishing reports, cited in Baker, 2004). Charter boat fishing companies and some tourism promotion materials promote the catching of Harlequin Fish in all of the ‘forementioned areas. Also, charter boat operations that visit the far west coast of S.A. (such as Fowler’s Reef, Fowlers Bay, and other locations) catch large to very large Harlequin Fish (e.g. see Wade, 2003; Murton, 2003). The National Recreational and Indigenous Fishing Survey (Henry and Lyle, 2003; SARDI data, 2005) estimated that about 157 Harlequin Fish were caught and kept by recreational fishers in South Australia during the survey period (May 2000 to April 2001), considerably fewer than the number caught in W.A. (see section above).
Harlequin fish are considered to be timid biters with poor fighting qualities when hooked by fishers. They suffer badly from barotrauma when retrieved from depth, but are not usually released by fishers anyway (S. Bryars, DEH, pers. comm., 2008).
Harlequin Fish was one of the targeted species in spear-fishing competitions in South Australia during the 1970s and 1980s (see Ottaway et al., 1980; Johnson, 1985a and 1985b). Harlequin Fish is promoted as a species for spear fishers to catch in S.A. (Smith, 2000; International Freediving and Spearfishing News, undated), and is known to be taken by some spear-fishers in S.A. (e.g. Scholefield 2008). More recently, Harlequin Fish (specimens over 1kg) was listed as one of the targets in the 54^th Australian Spearfishing Titles 2006, held on northern Kangaroo Island (Australian Underwater Federation, 2006). Records from that event showed that a total of 27 harlequin fish were speared along the north coast of Kangaroo Island (S. Bryars, DEH, pers. comm., 2008).
Harlequin Fish is part of the scalefish bycatch in the South Australian Rock Lobster Fishery (Sloan, 2003a), but the species is no longer allowed to be retained. Catch statistics in this fishery for all Serranids combined, are discussed above, in the section on Serranidae.

Vulnerable Characteristics of the Species, and Threatening Processes

Near-shore populations may be potentially vulnerable to decline, due to the solitary nature of the fish, benthic existence and strong site association with reefs and caves, assumed slow growth, large size, susceptibility to barotrauma, and inquisitive nature/attraction to divers. Since at least the 1980s, these characteristics are known to have made the species susceptible to impacts from spear-fishing, and Harlequin Fish numbers are reported to have been reduced in accessible areas of S.A. and W.A. due to “heavy spear-fishing pressures” (Hutchins and Swainston, 1986). According to Stagles (2005) their numbers were greatly reduced off Perth during the 1960’s and 1970’s by spearfishing and they have not recovered since. The fact that larger specimens can be found in the more lightly fished areas of WA (Stagles, 2005) suggests that over-fishing can cause localised depletion.
Many fish in the Serranidae have a low resilience to exploitation (Heemstra and Randall, 1999; Pogonoski et al., 2002).  In addition to the characteristics of slow growth, large size, solitary nature, slow movement and strong habitat association with reefs, the reproductive characteristics of Serranid fish increase their vulnerability to decline. Serranid fish are typically, but not always, protogynous hermaphrodites, and maintain specific population structures (e.g. ratio of males to females, and numbers per group). Exploitation can cause imbalances in population sex structure, and therefore affect reproductive potential.
Othos dentex exists over a relatively small depth range (reportedly to about 60m), and therefore coastal impacts that damage nearshore reef ecosystems may have a negative impact on populations of this species. Some researchers consider that the absence of this species at sites where it previously occurred may be an indicator of polluted conditions, such as increased siltation (Gomon, 2002; D. Turner, SARDI, pers. comm. to Reef Watch, 2006). 
In addition to line fishing by anglers, and spear-fishing, the charter boat industry poses an additional and possibly increasing threat to populations, particularly in areas where large Harlequin Fish are caught. Numbers of Harlequin Fish taken by recreational fishers are not monitored in S.A., and to date (2008), there are no bag limits, boat limits, or legal minimum sizes for Harlequin Fish taken by recreational fishers and charter boats in South Australia.
In W.A., Harlequin Fish is defined for fisheries management purposes as a “Category 1” species. Fish in this category are generally long-lived, slow-growing, mature at four years-plus, form semi-resident populations, are vulnerable to localised depletion due to their life history, and are of low abundance and/or highly targeted. Category 1 fish have low catch rates, and are highly valued for their fishing and eating qualities. For these reasons, Category 1 fish are considered to have a high risk of over-exploitation, and require a high degree of protection (Harrison, 2001; W.A. Department of Fisheries, 2004a).

Existing Conservation and Management Measures

In W.A., there is a recreational bag limit of 4 fish in the Serranidae (including Harlequin Fish and Breaksea Cod), and species in that family over 120cm or 30kg are protected from fishing (Harrison, 2001; W.A. Department of Fisheries, 2003b, 2004a). In the early 2000s, there was a proposal to reduce the bag limit to 2 Serranids, and introduce a legal minimum size of 30cm (Harrison, 2001), however this has not occurred to date (Fisheries Western Australia Recreational Fishing Guides, July 2004 and November 2004).
Harlequin Fish occur in a number of protected areas in W.A., such as the Rottnest Island Marine Reserve (Rottnest Island Authority, 2004). A recent study in the Kingston Reef Sanctuary off Rottnest Island showed that many fish species (including Harlequin Fish) were more abundant inside than outside the sanctuary zone (Kleczkowski et al., 2008), although harlequin numbers were very low (n = 3 inside, n = 1 outside), hence meaningful conclusions could not be drawn.

Management Notes and Recommendations

Given the vulnerable population characteristics of this species, coupled with lack of knowledge about the relative abundance of this species across S.A., and the concern (although largely anecdotal) about fishing-induced decline in population numbers during the past two decades, a ban on the taking of this species by spear, hook and line in S.A., may be a justified precautionary measure. This would require the species to be listed as Protected under the S.A. Fisheries Act.
The limited amount of qualitative and quantitative information available on the fishing of Othos dentex (see above), suggests that a greater number of these fish are taken per annum by recreational fishing and charter boat fishing, than by commercial fishing. Recreational fishing regulations for this species exist in W.A., but not in South Australia. In recent years, there has been an expansion in the number of charter boat vessels in S.A., and in the geographic area where such vessels target reef fish, including Harlequin Fish. The catching of large adult Harlequin Fish is promoted by a number of charter boat companies in South Australia. Charter boat fishing in South Australia is now more formally regulated, and a Management Plan has been released (PIRSA, 2004; Presser and Mavrakis, 2005). The plan includes a licensing system to limit the number of charter boat operators in each marine region of S.A. Also required is the logbook recording of species-specific catch and effort data for each charter trip undertaken, with data submitted each month to SARDI Aquatic Sciences (PIRSA, 2004; Presser and Mavrakis, 2005). It is noted that almost all of the species commonly caught by charter boats are included in a list of species codes to be used by the charter boat industry for reporting (PIRSA, 2005b); however Harlequin Fish is not included in the list, even though it is known to be a target species for some charter boats. A prohibition on catching and retaining Harlequin Fish is recommended (see above). If fishing for this species is not prohibited under legislation in the near future, then it is important that charter boat fishers’ record catch and effort information on this species, and strictly monitored catch limits should also apply (see below).
Currently, there are no recreational bag and boat limits for this species in S.A., for line fishers or spear fishers. If fishing for O. dentex is not prohibited under legislation in the near future, then legal minimum and/or maximum sizes should be introduced in the interim, as well as a conservative daily bag limit and boat limit (see W.A. Department of Fisheries, 2003b, 2004a, for examples).
All live specimens in the bycatch of rock lobster pots, shark gillnets, or long lines should be returned to the water if possible. In future, if a research project is undertaken on this species (see below), dead specimens from the bycatch could be retained and submitted to the relevant agency or university to assist in research on this species.
As with the groupers of the family (Pogonoski et al., 2002), recognition of the value of other Serranids for eco-tourism activities (e.g. recreational scuba diving) is important.
As is the case for groupers, there should be emphasis on the protection and restoration of adult and juvenile habitats, particularly those habitats that have been (or are being) degraded by land-based activities (Pogonoski et al., 2002).
Marine reserves / marine protected areas (MPAs) are beneficial for conserving populations of large, site-associated species such as Serranids (Baker, 2000; Pogonoski et al., 2002), and plans for new MPAs in South Australian coastal waters should consider this species and its habitats (Baker, 2004). Due to their susceptibility to barotrauma and apparent site-attachment, ‘no fishing’ Sanctuary Zones within MPAs may be the most effective means of conserving Harlequin Fish.

Research Recommendations

Although there are numerous location records for this species in S.A., no assessment has been undertaken to determine population sizes, or relative abundance in specific areas of South Australia. The species appears to be more commonly sighted (and caught) in Western Australia than in S.A., which is towards the edge of the species range. Harlequin Fish is currently one subject of a community-based Reef Watch “Feral Or In Peril” program in S.A., which aims to monitor the distribution and abundance of a number of potentially threatened species at various diving and snorkelling locations around the State. Although a diving and/or video survey program has not been undertaken for this species to date, community surveys such as Reef Watch may assist over time in determining changes in relative abundance at some of the nearshore reefs in South Australia.
Research surveys to determine the distribution and relative abundance of another potentially threatened reef fish species, Western Blue Groper, have been undertaken in nearshore reef habitats across South Australia (see synopsis for Achoerodus gouldii, and reports by Shepherd et al., 2002; Shepherd and Brook, 2002, 2004). Incidental data on Harlequin Fish sighted during those Blue Groper surveys will be utilised in future (S. Shepherd, SARDI Aquatic Sciences); however a targeted research survey for Harlequin Fish is also required. It is noted that in 2006, Reef Watch commenced community surveys at a site in GSV, specifically seeking Harlequin Fish, and divers’ logbook records were also being sought.
Very little is known of the biology (particularly reproduction), population dynamics or ecology of this reef species, despite it being an irregularly sighted species on nearshore reefs in W.A. (especially) and S.A., and a target for fishers. Research projects on the ‘forementioned topics may assist in determining the status of this species. Ageing studies, reproductive studies, diet analysis, and study of the ecological relationships of this species in its habitat, might all be useful.

Other Information

Harlequin Fish are popular with recreational SCUBA divers. Some dive groups and diving charter companies promote the presence of Harlequin Fish at locations where divers and dive charters visit (examples in S.A. include Rapid Head on the Southern Fleurieu, and St Francis Isles in the Nuyts Archipelago; and in W.A., include Rottnest Island, Albany area and Seal Island, amongst others).

Support for S.A. Listing:

Barry Hutchins (ex-W.A. Museum) recommended that the species be listed as threatened, and Graham Edgar (University of Tasmania) recommended Data Deficient category.