© 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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Rock Ling

© Chris Hall, MLSSA

Family Name:	Ophidiidae
Scientific Name:	Genypterus tigerinus Klunzinger, 1872
Recommended Status in S.A:	Near Threatened
Rationale:  Included here because (i) adult Rock Ling are very large, possibly long-lived, site-associated reef fish, and are highly esteemed as food, and vulnerable to over-exploitation by both commercial and recreational fishers; (ii) the species has a low resilience to exploitation; (iii) Rock Ling is considered to be an uncommon species in South Australia; (iv) the species is taken by spear, hook and line, nets and other recreational fishing gear, with no controls over numbers taken in most parts of the range (including S.A.), and Rock Ling is reported to have been virtually eliminated from some areas of southern Australia by recreational fishing, including netting and spear-fishing; (v) Rock Ling is a minor commercial species in Commonwealth fisheries and some State fisheries, and is also taken as bycatch in trawls, gillnets, pots, and with other gear; (vi) species-specific catch and effort data from commercial fisheries in State waters are inadequate, and there are few controls over the commercial fishing of this species; (vii) juvenile Rock Ling occur in shallow seagrass habitats, and may be vulnerable to habitat impacts; (viii) populations might be at risk from long-term climatic changes, and (ix) there is little information about the population sizes, biology or population dynamics of Rock Ling.

Page Contents

Current Conservation Status

No listings known

Distribution

Southern Australia and New Zealand

Rock Ling G. tigerinus is considered to be an uncommon species (Robins, in Nielsen et al., 1999).
Rock Ling occurs in temperate marine waters of Australia and New Zealand. In Australia, it is known from the central New South Wales coast around the south coast of Australia (including Tasmania) to south-western Western Australia (Hutchins and Swainston, 1986; Gomon, in Gomon et al., 194; Australian Museum, 2002l).

South Australia

Most known records in South Australia come from Gulf St Vincent and Spencer Gulf. Examples of locations in S.A. where the species has been recorded include north-central Spencer Gulf (e.g. “The Gutter”); the northern metropolitan (e.g. West Lakes), central and southern metropolitan (e.g. Port Noarlunga and Aldinga) area, including recent records from the 2000s; Fleurieu Peninsula (e.g. Rapid Bay); western Gulf St Vincent (e.g. Ardrossan); southern Yorke Peninsula (e.g. Chinamans Hat, and Edithburgh area) (Branden et al., 1994; MLSSA, 1999; K. Smith, unpubl. data, 2000, 2004; K. Smith, pers. comm., 2005; D. Muirhead, MLSSA, pers. comm., 2005; Australian Museum record, 1978; Museum of Victoria records, 2005, cited in OZCAM database, 2007; S.A. Museum records 1983, 1984, 1986, 1987, 1994, 2000, cited by T. Bertozzi, pers. comm., 2005, and OZCAM database, 2007; J. Baker, pers. obs., 2008).
There are also records from the South-east of South Australia, such as nearshore waters seaward of the southern Coorong (South Australian Museum record, cited in OZCAM database, 2004), and further south, towards the Victorian border (BRS data, cited in CSIRO, 2007).

Habitat

Juveniles inhabit seagrass-lined estuaries, and are often found under objects or small reef patches within the seagrass beds (Kuiter, 1993, 1996a; Gomon, in Gomon et al., 1994; Edgar, 2000). In Tasmania, juveniles have been recorded in low numbers in estuaries lined with Heterozostera seagrass, and on Flinders Island, one individual was recorded from Posidonia seagrass (e.g. Jordan et al., 1998).
Adults inhabit shallow, rocky reef areas, and are often found under ledges, and in caves and rocky recesses, where they often remain during the day. Also found around jetties, shipwrecks, artificial reefs (including tyre, concrete cubes, pipes and other structures) (Beinssen, 1976; Kuiter, 1993, 1996a; Branden et al., 1994; Gomon, in Gomon et al., 1994; Furlani, 1998; MLSSA, 1999; Edgar, 2000; Coutin, 2001; Australian Museum, 2002l).
Although Rock Ling often inhabit shallow reefs close to the shoreline in bays, inlets and along open beaches (FishNet, 2005), adults sometimes move away from inshore areas, and are often found in coastal reef areas in burrows under rocks, in waters 15m deep or more (Kuiter, 1993).
In Victoria, near the Ricketts Point Marine Sanctuary, the species has been recorded on unvegetated soft sediments (Plummer et al., 2003). Another example of a habitat in which G. tigerinus has been recorded, is coarse sand bottom nearly 50m deep, in a clump of sessile invertebrates composed of sponges, with some hydroid, ascidians and bryozoans (Roob and Currie, 1996, cited by Plummer, 2003).
The published depth range for Australian waters is from the shallows (e.g. 0m; 3m) to around 60m (Hutchins and Swainston, 1986; Kuiter, 1993; Robins, in Nielsen et al., 1999; Edgar, 2000).

Notes on the Biology

Growth and Age

Rock Ling reaches a maximum size of around 1.2m (Hutchins and Swainston, 1986; Gomon, in Gomon et al., 1994; Robins, in Nielsen et al., 1999).
To date, the largest size on record is 7.080kg, being a specimen taken off Bicheno in Tasmania, in 1979 (Australian Underwater Federation, 2003). Other record specimens (taken by spearfishing) including an individual weighing 5.075kg (Hutchins and Swainston, 1986). Maximum sizes of specimens that may have been Rock Ling G. tigerinus, recorded by the Australian Anglers Association Records Authority, include 4.325kg (taken from Westernport Bay in 1988), and 3.44kg (taken from Port Phillip Bay in Victoria, in 1984) (Australian Anglers Association, 2003, 2005).
No information is available on the maximum age of Rock Ling G. tigerinus, but it is noted that the related Pink Ling G. blacodes, may live to 30 years (Robins, in Nielsen et al., 1999, cited in Froese and Pauly, 2007).

Diet

Rock Ling are known to eat rock lobsters (Winstanley, 1977, cited in Kailola et al., 1993); seagrass-dwelling fishes (Hindell, 2006), and crabs such as Nectocarcinus species (S. Shepherd, SARDI, pers. comm., 2006).

Reproduction

Members of the family Ophidiidae are oviparous, with pelagic larvae. There is no special larval stage (Nielsen et al., 1999).
There appears to be little information specific to Rock Ling; however larvae that may be G. tigerinus have been caught in coastal waters around Tasmania during spring and summer months (Furlani, 1998, cited in Froese and Pauly, 2007; Kailola et al., 1993, cited in Bruce et al., 2002).

Other Information

Gummy Sharks prey on Rock Ling (Edgar and Shaw, 1995b).

Fisheries Information

Commercial – Commonwealth

Rock Ling G. tigerinus is caught commercially, and marketed under its correct common name (Seafood Services Australia, 2005). Rock Ling is commercially less important than Pink Ling (G. blacodes) due to the difficulty of catching large enough quantities to justify the effort (Gomon, in Gomon et al., 1994), but it is of equal value as a food fish (Robins, in Nielsen et al., 1999). Pink Ling is discussed briefly in the section above on Ophidiidae, because, although it is a species of conservation concern, it is found in deep water (including continental slope), and the exploitation of Pink Ling is managed by the Commonwealth.
In the Commonwealth-managed South East fisheries, Rock Ling may be caught in Commonwealth waters (outside 3 nm), but not in coastal waters (inside 3nm), with a concession that allows methods other than trawl, and there are no Commonwealth catch limits (AFMA, 2005b).
G. tigerinus is a minor component of the total ling catch in the Commonwealth’s quota-managed South East fisheries, and is rarely caught in quantity by trawlers in the SETF (FRDC project No. 97/117, cited in FRDC web site, 2002). The ling catch in the South East fisheries comprises mostly the deeper water ling G. blacodes (Pink Ling); however G. tigerinus is listed as being taken in shallower waters in both the South East Trawl (SET) and the South East Non Trawl (SENT) fisheries (Bruce et al., 2002). Based on AFMA logbook data, the National Oceans Office Neptune Data Directory (2003) also listed both G. tigerinus and G. blacodes (see note below) as species caught in the Commonwealth-managed drop-line and demersal set long-line fisheries (part of the South East Non-Trawl Fishery). Wayte et al. (2004) listed G. tigerinus as a retained by-product in the otter trawl sub-fishery of the South East Trawl Fishery. Similarly, Bromhead and Bolton (2005) reported that G. tigerinus is a retained by-product in the Gillnet, Hook and Trap Fishery, and the South East Trawl Fishery.
By-catch experiments during the mid 1970s in the Southern Shark Fishery, showed that Rock Ling is susceptible to capture in gillnets of various sizes, including 2-inch, 3-inch and 5-inch mesh, with catch in the order of 10 -20 specimens per 1000 km-hours (Walker et al., 2003). It is noted that small-mesh gillnets are not currently used in that fishery. Recent bycatch figures of Rock Ling in the Southern Shark Fishery are not available for this report.
Rock Ling is a minor component of the Commonwealth-managed Small Pelagic Fishery, observed in less than 5% of the trawl shots (AFMA, 2005a).

Commercial – Southern States

BRS (2004a) reported that in both Victoria and W.A., the catches of Rock Ling were up to 1t per annum during most years of the 1990s. The accuracy of the quantities specified in these BRS database records has not been confirmed for this report.  It is noted that there are records of the species taken commercially in Port Phillip Bay and Bass Strait (Anonymous, 2002b).
In New South Wales, the species is a minor part of the bycatch in estuarine prawn trawl fishing in the Sydney area (Liggins et al., 1996; New South Wales Fisheries, 2002). In N.S.W., Rock Ling is caught as trawl bycatch in deeper coastal waters (e.g. see example in Australian Museum, 2002l, of a specimen trawled from 60m, off southern New South Wales).
In Tasmania, the commercial fishery for Ling in State waters is small and consists mainly of Rock Ling, taken with gillnets. During the early 2000s, the status of the fishery was reportedly unknown (DPIWE website, 2002). As shown below, catches of over 20t per annum were recorded between 1992 and 1997, but catches have declined annually since that time, to a catch level similar to that recorded in 1990. The commercial catch in 2001was 5.2 tonnes (DPIWE statistics, 2002). During the mid-2000s, statistics were no longer publicly available for this fishery (e.g. DPIWE Tasmania, 2006e), possibly due to the low catch levels following over-exploitation by commercial and recreational fishing in combination (Figure 6).

Figure 6 Commercial catch of Rock Ling in Tasmanian Waters 1990 – 2001

(based on General Fishing Returns & Commonwealth GN01, GN01A & SSJF logbook returns; DPIWE statistics, 2002).

Rock Ling is a minor component of the commercial fish catch in W.A. Combined catch of Ling (Rock and/or Pink) from all fisheries in W.A. is provided (Table 19).

Table 19 Reported Catches of Ling (Rock and/or Pink) from WA waters 1994 to 2005
Year	Live weight (kg)
1994/95	1,195
1995/96	1,005
1996/97	-
1997/98	305
1998/99	677
1999/00	38
2000/01	-
2001/02	-
2002/03	704
2003/04	-
2004/05	-

(W.A. Fisheries Research Services Division statistics 1995-2001, extracted from W.A. Fisheries website, 2003, and W.A. State of the Fisheries reports, 2000/01 to 2005/06)

In W.A., Rock Ling G. tigerinus is also reported to be a minor bycatch of rock lobster pots operating in deeper waters (i.e. outside of the 100 fathom mark) (Department of Fisheries, Western Australia, 2004g, citing personal communication with a rock lobster fisher), but it is possible that the species caught at such depths is the Pink Ling G. blacodes.

Commercial – South Australia

In South Australia, capture of G. tigerinus is managed by the State within 3 nautical miles (NM), and by the Commonwealth outside of 3NM (AFMA, 2002a).
In South Australia, Ling catches recorded in the South Australian Research and Development Institute’s catch and effort database, likely refer mainly to the Pink Ling G. blacodes. Recorded catches of “Ling” in S.A. were in the low hundreds of kilos per annum from a number of the 1-degree fishing block during the late 1990s, and catches were mainly from Commonwealth-managed areas, south of Eyre Peninsula and Kangaroo Island, in waters deeper than the known depth limit of Rock Ling. Ling are also caught commercially in State waters, such as western Investigator Strait (north-western Kangaroo Island). In one year of the mid 1990s, around 1.3 tonne was recorded as being taken from the mid-west coast waters off western Eyre Peninsula, in a fishing area that stretches from the Anxious Bay coast, as far south-west as the Investigator Group of islands. It is not known whether such catches that occur closer to the coast, comprise Rock Ling or Pink Ling, or both. Ling may also be coded as unidentified species and therefore it is difficult to provide an accurate estimate of the catch (S. Shepherd, per. comm., 2006). There is no targeted effort for Ling in S.A. waters. During the 1980s total reported catches in the Marine Scalefish fishery in S.A. usually amounted to several hundred kilograms per annum, other than a larger catch of 1.3t in 1987/88. During the 1990s, catches were higher in some years, e.g. 1.5t in 1992/93 and 1995/96; 1.8t in 1993/94; 1.9t in 1998/99; 2.1t 1996/97 and 2.8t in 1997/98. Due to confidentiality (in cases where less than 5 fishers recorded catches), data for the early 2000s are not available for this report.
In S.A, Rock Ling is also caught as bycatch in prawn trawls (S.A. Museum records, 1987; Museum of Victoria records, 2005). In a bycatch sampling program in the Spencer Gulf Prawn Trawl Fishery during the mid-1990s, 3 Rock Ling were recorded in 32 trawl tows (Carrick, 1997). The Museum of Victoria also houses specimens of Rock Ling taken by prawn trawl at “The Gutter” in Spencer Gulf, in 2005.
Ling (Genypterus spp.) that are caught in rock lobster pots as bycatch, in the South Australian Rock Lobster Fishery, are permitted to be retained for sale (Sloan, 2003). In a bycatch monitoring program during the early 2000s, 7 specimens of G. tigerinus were recorded in logbooks, a sample of about 57% of the pot-lifts in the Southern Zone (Brock et al., 2004). If that figure is representative, then annual catch may therefore be in the vicinity of 10 to 12 specimens in that zone.
In S.A., the species is a minor part of the bycatch in the Blue Crab fishery. Catch figures for the early 2000s are provided (Table 20) (from Svane and Hooper, 2004; Currie and Hooper, 2006).

Table 20 Bycatch of Rock Ling in the S.A. Blue Crab Fishery, 2002 – 2005
	Spencer Gulf	Gulf St Vincent
2002	0	0
2003	0	5
2004	0	8
2005	5	11
(Svane and Hooper, 2004; Currie and Hooper, 2006)

Recreational

The Rock Ling is well regarded as a food fish, is considered an important recreational fish (Gomon, in Gomon et al., 1994; Prokop, 2000). The species is caught by anglers (e.g. Lyle and Campbell, 1999; FishNet, 2005), taken as part of mixed catches in cooler waters (Prokop, 2000). The species has been included in angling records from fishing clubs (e.g. Australian Anglers Association branches in Victoria and W.A.). It is noted that in S.A., there is a museum record of this species taken by recreational fishing from Rapid Bay Jetty, using pilchard bait (South Australian Museum record F 07678, cited in OZCAM database, 2004).
G. tigerinus is considered highly susceptible to spear-fishing (Edgar, 2000), which would include both the juveniles in estuaries, and the adults in shallower waters within spear-fishing range (e.g. 5m – 20+m). Two of the largest specimens on record were taken by spearfishing (see Hutchins and Swainston, 1986, and Australian Underwater Federation, 2003). In Victoria, recreational fishing groups report that the species is speared at various locations, including natural and artificial reef habitats in Port Phillip Bay, where Rock Ling is occasionally found in caves, under ledges, and in tyres, pipes and other structures. Rock Ling (incorrectly referred to as G. blacodes, the deeper water species) was one of the species taken in recreational fishing competitions in S.A. during the 1980s (see Johnson, 1985a and 1985b). More recently, Rock Ling (with specimens over 0.4kg) was listed as one of the targets in the 54^th Australian Spearfishing Titles 2006, held on northern Kangaroo Island (Australian Underwater Federation Inc., 2006).
The species is also considered to be highly susceptible to gill netting (Edgar, 2000). In south-eastern Tasmania, G. tigerinus is caught over reefs and soft-bottom habitats by recreational gill-netters (Lyle et al., 2000), and by other nets, and lines. The size of the recreational catch in Tasmania is unknown. There is a bag limit of 30 and a possession limit of 45 Rock Ling for recreational fishers in Tasmania waters (DPIWE website, 2002).
In Victoria, the minimum legal size is 33cm for ling (both G. tigerinus and G. blacodes) taken by recreational fishers, and there is a general daily bag limit of 40 scalefish (all species combined, which would include ling) (DPI Victoria web site, 2004).
The National Recreational and Indigenous Fishing Survey (Henry and Lyle, 2003) reported that 4,500 Ling (species unspecified) were caught and kept by recreational fishers in southern Australian states during the survey time period (May 2000 to April 2001), comprising 1,258 specimens in New South Wales; 2,019 in Victoria; 156 in South Australia; and 1,067 in Tasmania. Given the inshore nature of Rock Ling, and the offshore distribution of Pink Ling, it is likely that a significant proportion of the unspecified “Ling” caught by recreational fishers during this survey, were the Rock Ling G. tigerinus.

Vulnerable Characteristics of the Species

Juveniles are often found in shallow seagrass beds in the nearshore area, and may thus be vulnerable to decline from impacts on habitat.
Adults are large, slow-moving and site-associated on shallow reefs and other underwater features, and are thus vulnerable to capture by fishers.
The species is reported to have a very low resilience to exploitation, in terms of minimum population doubling time (based on growth and/or fecundity estimates) (Froese and Pauly, 2006).
Rock Ling appear to be uncommon in South Australia.

Threatening Processes

Fishing is the main threatening process. Rock Ling is a large, reef-associated fish that is highly vulnerable to capture. In some areas, lings “have been mostly eliminated by netting and spearing” (Gomon, in Gomon et al., 1994). Edgar (2000) reported that Rock Ling “seem to have virtually disappeared from much of the southern coast”, due to their high susceptibility to spear-fishing and gill-netting. Nevill (2006) reported on a community survey that showed apparent reduction over time (from 1959 to 1982), in Rock Ling numbers at one spear-fishing site in Port Phillip Bay, and numbers had not recovered by 2006.
Wayte et al. (2004) listed Rock Ling G. tigerinus as being of moderate risk of population impacts from trawl capture in the South East Fishery.
Apart from fishing, populations might be at risk from long-term climatic changes (G. Edgar, University of Tasmania, pers. comm., 2006).
In some areas, coastal developments and discharges that affect the quality of benthic habitat might be a threat to nearshore populations of this species.

Research Requirements

Surveys are required to ascertain the full spatial distribution and relative abundance of this species in South Australia.
There is a paucity of data on the biology, (including reproduction), and population dynamics of this species.

Management Requirements

Species-specific data on catch and effort by commercial and recreational fishers in State waters is lacking, and this includes South Australia. Ling catch and effort statistics should be separated by species.
Restrictions on the commercial and recreational take (the latter including angling and spearfishing) are required.
In fisheries for invertebrates such as rock lobster and crab, pot and trap designs that reduce the bycatch of benthic fish species (such as Rock Ling) should be encouraged.
No-take marine reserves across the range may assist recovery of depleted populations. It is noted that in Tasmania, several years after the Maria Island Marine Reserve was set up, numbers of Rock Ling G. tigerinus increased in the reserve, relative to surrounding fished areas. The scientists monitoring that reserve (G. Edgar and N. Barrett) considered that the Rock Ling was one of the over-fished species that locally benefits from the existence of the reserve (see Edgar and Barrett, 1997, 1999; Barrett and Edgar, 1998). However, only one individual has been recorded within the Maria Island Marine Reserve during more recent annual surveys (1998-2004), indicating that populations may be influenced by long-term climatic cycles (G. Edgar, University of Tasmania, pers. comm., 2006).

Other Information

Few species in the Ophidiidae family occur in shallow water, but the Rock Ling G. tigerinus is one of those that do.
It is noted that Food and Agriculture Organisation of the United Nations (see FAO, 2000i) considers the species G. tigerinus (Rock Ling) to be the same as the Pink Ling (G. blacodes). In Australia, G. tigerinus and G. blacodes are considered to be separate species (see Daley et al., 1998; Australian Museum, 200l).
The species occurs in a number of protected areas in Victoria, such as Wilsons Promontory Marine National Park (MNP) (Edmunds et al., 2003); Ricketts Point Marine Sanctuary, and the Point Addis MNP, on the Great Ocean Road coast (Roob and Currie, 1996; Jenkins et al., 1996, cited by Plummer et al., 2003; Edmunds et al., 2003).

Support for S.A. Listing:

Graham Edgar (University of Tasmania), and Barry Hutchins (ex-WA Museum).