|Scientific Name:||Orectolobus maculatus|
|Species Authority:||(Bonnaterre, 1788)|
Squalus appendiculatus Shaw & Nodder, 1806
Squalus barbatus Gmelin1788
Squalus lobatus Bloch and Schneider, 1801
Squalus maculatus Bonnaterre, 1788
|Taxonomic Notes:||Often confused with O. halei, but differs from O. halei by having more (6-10 dermal lobes at the posterior preorbital group) and saddles containing whitish rings and blotches (unlike O. halei).
Western Australia (WA) populations of O. maculatus appear to include at least two species with a dwarf morph similar to O. maculatus but maturing at a smaller total length (J. Chidlow pers. comm.). Clearly, further taxonomic research on the WA populations is warranted.
Assessment is complicated by taxonomic uncertainties of apparent specimens from Japan and South China Seas, but due to the probable invalid nature of these records, this species should be considered an Australian endemic at present (L.J.V. Compagno, March 2003, pers. comm.).
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Assessor/s:||Huveneers, C. Pollard, D., Gordon, I., Flaherty, A. & Pogonoski, J.|
|Reviewer/s:||Valenti, S.V. & IUCN SSG Australia and Oceania Red List Workshop participants (Shark Red List Authority)|
The wobbegongs Orectolobus ornatus and O. aculatus were assessed on the 2003 Red List of Threatened Species as Near Threatened globally. Recent studies, however, have provided new biological and ecological information while previous taxonomic uncertainties in NSW have now been resolved, elevating O. Halei to species level (previously believed to be the adult form of O. ornatus). This assessment presents updated documentation for O. maculatus.
The Spotted Wobbegong (Orectolobus maculatus) is probably an Australian endemic species (pending taxonomic review). Previous records from Japan and South China Sea could be different species of wobbegongs. A biologically vulnerable species, site-attached within its relatively shallow water range (0?218 m) and caught in commercial and recreational fisheries as a target species and as bycatch. Historic catch data are aggregated between wobbegong species, but serious declines (>50% between 1990/1991?1999/2000) for Ornate Wobbegong (O. ornatus), O. maculatus and Banded Wobbegong (O. halei) are documented for the east coast (New South Wales). Catches have since stabilized, however, species-specific catch-per-unit-effort data are unavailable due to inaccurate reporting of fishing effort and aggregation of wobbegong species in catch records. Until late 2006, there were no management strategies specifically regulating the wobbegong commercial fishery in NSW. Since September 2006, wobbegongs have been included in the daily trip limit for a specific list of shark species to one tonne for a 24 hour period and two tonnes for 48 hours or greater. Furthermore, a minimum size limit of 130 cm TL and a maximum trip limit of either six or 12 wobbegongs (including O. halei and O. ornatus) will also be implemented and is pending approval by the NSW Fisheries minister. Given the targeted wobbegong fishery, documented decline in catches and previous lack of management regulations, O. maculatus is classified as Vulnerable in NSW. Wobbegongs are not targeted and catches are low in other Australian states (Western Australia, Queensland, South Australia, and Victoria). However, given that localised depletion is possible due to wobbegong?s slow reproductive cycle (triennial) and long residency within small geographical areas, and that O. maculatus is caught across its range, O. maculatus is classified as Near Threatened globally. More information is needed on catch composition, fishing effort, age and growth and population structure to develop stock assessments and demographic analyses. Wobbegong resilience to fishing pressure could then be calculated and used to recommend future conservation and management decisions. Monitoring of catches will also be required due to the recent management regulations that have been introduced in NSW, limiting fishing pressure on wobbegongs. Reassessment might then be required in light of this new information.
Orectolobus maculatus is most likely an Australian endemic wobbegong.
Orectolobus maculatus has been recorded from tropical eastern Australia with confirmed reports from Gladstone (22°S), Queensland (Kyne et al. 2005) southwards to Hobsons Bay (37°52'S), Victoria, westwards to St. Vincents Gulf (35°10'S, 137°55'E), South Australia, and north-westwards to Bessieres Island (21°23?S, 114°41?E), Western Australia (J. Chidlow unpub. data). Tasmanian records are probably invalid (Last and Stevens 1994).
Previous sources (Last and Stevens 1994, Compagno 2001) show that the global distribution of O. maculatus includes Japan and the South China Sea. However, wobbegongs from these areas could be different undescribed species of wobbegongs.
Native:Australia (New South Wales, Northern Territory, Queensland, South Australia, Victoria, Western Australia)
|FAO Marine Fishing Areas:||
Indian Ocean – eastern; Pacific – southwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||No evidence of subpopulations. However, as stated above, a potential dwarf population of O. maculatus occurs in WA. A genetic study looking at orectolobid phylogeny and phylogeorgaphy and assessing potential stock structure is currently being undertaken (S. Corrigan pers. comm.).|
|Habitat and Ecology:||
Compagno (2001) describes this species as ?an abundant, temperate to tropical, inshore to offshore bottom shark of the continental shelves of the western Pacific, commonly on coral and rocky reefs, in coastal bays, in estuaries, in seagrass beds, under piers, and on sandy bottoms.? Juveniles occur in estuaries and are occasionally found over seagrass beds. It can occur in water barely deep enough to cover it, and has been observed climbing ridges between tide pools with its back out of water (Compagno 2001). In a study in Port Stephens, NSW, a sympatric species of wobbegong (O. ornatus) was shown to prefer sponge gardens, artificial structures and barren boulders habitats with a high topographic complexity and crevice volume (Carraro and Gladsone 2006). However, O. ornatus did not seem to select habitat on the basis of prey availability and habitat selection may therefore be related to predator avoidance (Carraro and Gladsone 2006). Orectolobus maculatus occurs inshore on the continental shelf to at least 218 m depth (Kyne et al. 2005). It is often found in murkier water than the closely related O. Halei (Lieske and Myers 1994).
A survey on wobbegongs shows evidence of site-attachment with divers observing individual sharks in exactly the same positions over consecutive dives (The Ecology Lab 1991). Furthermore, a sympatric species of wobbegong (O. halei) has been recorded within the same area for over 2.5 years (Huveneers et al. 2006, Huveneers unpub. Data), and another sympatric species of wobbegong (O. ornatus) has been re-sighted within a 75 hectares area for a period of over 211 days suggesting site fidelity (Carraro and Gladstone 2006).
Compagno (2001) describes this shark as a nocturnal species that rests on the bottom during the day in caves, under ledges on reefs, and in trenches and that undertakes nocturnal excursions away from resting areas. As a primarily nocturnal feeder, it preys on bottom invertebrates and fishes (Last and Stevens 1994). Compagno (2001) cites the prey of O. maculatus as bony fishes, sharks, rays, cephalopods and crustaceans. A NSW study found elasmobranchs, osteichthyes (reef, benthic and a few pelagic fishes, and moray eels) and cephalopods as prey items (Huveneers et al. 2007a). No crustaceans were found in the stomachs of O. maculatus caught in the NSW. Sampled sharks were, however, mostly large juveniles and adults (>100 cm TL), and it is possible that crustaceans are part of neonates or small juveniles diet.
Although O. maculatus was reported to mature at about 60 cm (Compagno, 2001), this size-at-maturity is likely to be related to the dwarf morph from WA, whereas O. maculatus matures at about 120 cm (Huveneers et al. 2007b). Similar to O. ornatus and O. halei, O. maculatus has a triennial reproductive cycle with follicles taking two years to enlarge before ovulation. During the first year, follicles remain small, then grow rapidly during the second year prior to ovulation during November. Gestation lasts about 10?11 months with parturition occurring during September?October (Huveneers et al. 2007b). O. maculatus is lecithotrophic viviparous with a litter size of about 21 with up to 37 young recorded (Grant 1978) and a size-at-birth of about 23 cm TL (Huveneers et al. 2007b). Maximum length is about 320cm, but with most individuals caught being smaller, up to 150?180 cm (Compagno 2001).
Age and growth of O. maculatus was attempted but could not be verified or validated (Chidlow, 2003, Huveneers 2007). Furthermore, different age estimations for wobbegongs were obtained if using whole vertebrae or thin cut sections (Huveneers 2007). Newborn captive O. Maculatus grew about 22 cm year-1, whereas small juveniles of about 45 cm TL grew about 18 cm year-1 (Huveneers 2007).
Commercial fishing is probably the main cause of the decline of this species in eastern Australia. Furthermore, observed site fidelity is likely to increase wobbegong?s susceptibility to fishing pressure. On an Australia-wide basis, wobbegong sharks are commonly caught in trawls, beach seines, gillnets, lobster pots and traps, by hook-and-line, and also by spearfishing. The flesh is now highly regarded as food, but in the past has generally been of only limited commercial value. Historically, the attractive skin has been used as decorative leather (Last and Stevens 1994). However, it is unknown if this practice is still occurring.
In NSW, three Orectolobus species (O. maculatus, O. ornatus and O. halei) are taken in the Ocean Trap and Line Fishery (OTL), in the fish and prawn sectors of the Ocean Trawl Fishery, and very few in the Estuary General Fishery. The majority of commercial wobbegong catches occur in the OTL Fisheries, where they have historically been taken as both a target species by setline methods and as by-product by other methods (NSW Department of Primary Industries, unpub. data). Serious declines have been observed in NSW, demonstrating the vulnerability of this species to exploitation. The NSW total catch of wobbegongs (genus Orectolobus), combining all fishing methods and fisheries, has declined from about 120 tonnes in 1990/1991 to about 55 tonnes in 1999/2000, representing a decrease of about 55% in less than a decade (Pease and Grinberg 1995, NSW Department of Primary Industries unpub. Data). However, catches have since stabilised, and range 55?73 tonnes during 1998/1999?2003/2004. Fishing effort is mostly unknown and inaccurate because it has only been reported as the number of days fished. Additionally, the historical aggregation of the wobbegong species in catch data is a further complicating factor. Species-specific catch-per-unit-effort, required to obtain a more accurate estimation of wobbegong catches, is therefore unavailable. Although the strong decline in catches should be of concern for the resilience of wobbegongs to strong fishing pressure, the number of fishers landing wobbegongs has also decreased from about 520 in 1990/1991 to about 250 in 2003/2004 (NSW Department of Primary Industries unpub. data).
Commercial fishing by a variety of methods is potentially threatening wobbegong species in southern Australian waters. In southern Australia, wobbegongs are taken within the Southern and Eastern Scalefish and Shark Fishery (SESSF) (AFMA logbook data, unpub. Data). Most of the above fisheries take these species as bycatch, and like many bycatch species they are often utilised. Retained wobbegong from the Commonwealth Fisheries ranged 2.3?5.1 tonnes between 1994 and 1999.
Orectolobus maculatus and O. halei are a component of the bycatch of a commercial shark fishery utilising demersal gill-nets that target carcharhinid whalers and other sharks along the southern and lower west coasts of Western Australia with an average total wobbegong catch between 1999 and 2006 of about 45 tonnes year-1 (range 35?68 tonnes) (Simpfendorfer and Donohue 1998, Penn 2001, McAuley and Lenanton 2003, McAuley and Gaughan 2004, Gaughan and Chidlow 2005, McAuley 2006, McAuley 2007). Smaller catches of orectolobids also occur in commercial and recreational rock lobster pots throughout temperate coastal Western Australian waters (J. Chidlow, pers. comm.).
Commercial catches of wobbegong are small in most parts of South Australia (about 0.5?2.5 tonnes) with the highest yearly catch being 3.1 tonnes in 1987/88.
Wobbegongs are not targeted in Queensland. O. halei has been recorded in low numbers in the bycatch of prawn trawl fisheries (Kyne et al. 2002), whereas small wobbegongs are sometimes caught by crab pots in Southeast Queensland and Moreton Bay, but are usually discarded (J. Stead pers. comm.).
The National Recreational and Indigenous Fishing Survey (Henry and Lyle 2003) reported that 5,174 wobbegongs (all species combined) were caught and kept by recreational fishers in southern Australian states during the survey time period (May 2000?April 2001), comprising 1,944 from NSW, 999 from Queensland, 252 from SA, and 1,978 from WA. In Western Australia, a WA Fisheries Department survey conducted in 1996?1997 between Augusta and Kalbarri, reported that up to 1,000 wobbegongs were caught and kept by recreational fishers during that period (Sumner and Williamson 1999).
As a result of the observed decline in NSW wobbegong catches, a discussion paper on wobbegong sharks was produced, seeking the views of various stakeholders on the future management of commercial and recreational fishing of wobbegong sharks (NSW Fisheries 2001). However, the management plan has not been finalised and management measures have not been implemented. NSW Department of Primary Industries (NSW DPI) also requested commercial fishers to report catches for O. ornatus and O. maculatus individually. Most recently, a review of NSW Recreational Freshwater & Saltwater Fishing Rules and the Fishery Management Strategy (FMS) for NSW Trap and Line Fishery have proposed a minimum size limit of 130 cm TL for wobbegong sharks and a trip limit of 12 wobbegongs caught in fish traps (NSW DPI 2006). The FMS has also recommended that commercial fishers report their catches of each species separately and to collect additional biological data through the observer program.
Until late 2006, there were no management strategies specifically regulating the wobbegong commercial fishery in NSW. The only regulation in place was a recreational bag limit of two wobbegongs per day (later reduced to zero in September 2007) and a commercial gear limit of no more than ten lines each with a maximum of six hooks when setlining within three nautical miles of the coast. There were no gear limits outside three nautical miles, but as of 2008, amendments to the share management plans will instate a maximum of 1,200 hooks and 30 traps per endorsement holder.
Since September 2006, wobbegongs have been included in the daily trip limit for a specific list of shark species to one tonne for a 24 hour period and two tonnes for 48 hours or greater. NSW DPI also recommended that fishers in the Ocean Trap and Line and Lobster fisheries have in their codes of practice to release wobbegongs less than 130 cm TL caught in fish traps. Since July 2007, the use of wire trace, or other trace made of metal type materials, is prohibited to decrease instances of gut-hooking. Furthermore, a minimum size limit of 130 cm TL and a maximum trip limit of either 6 or 12 wobbegongs (including O. halei and O. ornatus) will also be implemented and is pending approval by the NSW Fisheries minister.
Site attached species may also benefit from habitat protection and suitably designed and implemented "No-take" MPAs, where all forms of harvesting or fishing are excluded. Some protection may be offered by those protected areas already being implemented for grey nurse sharks Carcharias taurus in NSW.
Australian Marine Protected Areas in which the species occurs:
Great Sandy Marine Park, Qld
Moreton Bay Marine Park, Qld
Cape Byron Marine Park, Byron Bay, northern NSW
Julian Rocks Aquatic Reserve, off Byron Bay, northern NSW
Solitary Islands Marine Park, north of Coffs Harbour, NSW
Port Stephens-Great Lakes Marine Park, north of Sydney, central NSW
Jervis Bay Marine Park, south of Sydney, NSW
Batemans Marine Park, south of Sydney, NSW
Shark Bay Marine Park, WA
Ningaloo Marine Park, WA
Jurien Bay Marine Park, WA
All Victorian marine parks
All South Australian marine parks
Possibly also occurs in the following areas:
Hamelin Pool Marine Nature Reserve, WA
Shoalwater Islands Marine Park, WA
Marmion Marine Park , WA
Muiron Islands Marine Management Area, WA
Rowley Shoals Marine Park , WA
Further protected areas might be necessary to ensure stable populations and are likely to be efficient due to the high site fidelity of wobbegong (Huveneers et al. 2006).
Recreational fishers may also have had an impact on this species in the past. An in-possession limit of two wobbegong sharks per person was introduced for recreational fishers in NSW and reduced to zero in September 2007. This new regulation may help to alleviate any adverse affects caused by recreational fishing practices.
Although a PhD project investigated the biology and ecology of wobbegong sharks, as suggested by the previous Red List assessment, catch and effort is still poorly recorded preventing adequate stock assessments. Species-specific catches in addition to accurate effort data is required to correctly determine population status of wobbegong.
The improvement of species identification in catch records and a better understanding of biological parameters, including validation of age and growth are crucial in providing accurate data upon which to base stock assessments and demographic analyses. Outcomes from which can then be used to estimate wobbegong resilience to fishing pressure and recommend future conservation and management decisions.
|Citation:||Huveneers, C. Pollard, D., Gordon, I., Flaherty, A. & Pogonoski, J. 2009. Orectolobus maculatus. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 08 March 2014.|
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