|Scientific Name:||Orectolobus hutchinsi|
|Species Authority:||Last, Chidlow & Compagno, 2006|
|Taxonomic Notes:||As Orectolobus sp. nov. A, this was given a DISCARDED flag because is was an undescribed species assessed as LC; therefore it did not appear on the published Red List until 2009.|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Huveneers, C. & McAuley, R.B.|
|Reviewer(s):||Walls, R.H.L. & Kyne, P.M.|
|Facilitator/Compiler(s):||Kyne, P.M., Walls, R.H.L., Simpfendorfer, C. & Chin, A.|
The Western Wobbegong (Orectolobus hutchinsi) is a medium-sized (to at least 149 cm total length) wobbegong, endemic to Australia. This species is known only from shallow waters on the continental shelf off southwest Australia, between Coral Bay and Groper Bluff, at depths of 0.1-106 m. The biology (reproduction, age and growth) of this species is better known than other sympatric small wobbegongs (family Orectolobidae), with females breeding every two or three years and producing 18-29 young per litter. Although the Western Wobbegong is caught more frequently than other small wobbegongs, the species is a minor bycatch component of the Western Australian temperate demersal gillnet and demersal longline fisheries, which only catch ~40 tonnes of wobbegongs per year. In addition, the Western Wobbegong is unlikely to be retained due to its small size and post-release survival of wobbegongs is expected to be high. Further research is required on the species' occurrence and capture in fisheries, but there is no evidence to infer or suspect population decline; the species is therefore listed as Least Concern.
|Previously published Red List assessments:||
|Range Description:||The Western Wobbegong is an Australian endemic, known only from the inner continental shelf off southwest Australia from Coral Bay (23°08'S, 113°46'E) to Groper Bluff (34°30'S, 118°54'E) in the Eastern Indian Ocean (Last et al. 2006, Last and Stevens 2009).|
Native:Australia (Western Australia)
|FAO Marine Fishing Areas:||
Indian Ocean – eastern
|Lower depth limit (metres):||106|
|Upper depth limit (metres):||0|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Nothing is known of the population size or trend for this wobbegong.|
|Current Population Trend:||Unknown|
|Habitat and Ecology:||The Western Wobbegong is found on the continental shelf at depths of 0.1-106 m (Chidlow et al. 2007). The species reaches at least 149 cm total length (TL) (Last et al. 2006). Male specimens are mature at 112 cm TL and female specimens at 110 cm TL. Females probably breed every two or three years and produce 18-29 young per litter after a gestation period of 9-11 months, with parturition occurring between July and September (Chidlow 2003). Offspring are born at a size of 22-26 cm TL with an embryonic sex ratio that does not significantly differ from 1:1 (Chidlow 2003).
Von Bertalanffy growth parameters estimated from vertebral cross-sections and an assumed annual banding pattern were L = 149.45 and K = 0.117 year-1. Although the periodicity of vertebral band formation in captive animals did not support synchronous annual vertebral band deposition, captive growth rates matched those predicted with an annual band-deposition frequency (Chidlow et al. 2007).
|Use and Trade:||
In Australia, wobbegong (family Orectolobidae) flesh is sold locally for human consumption through ‘fish and chip’ and fresh fish retail outlets. Most commercially landed wobbegong catch however, is comprised of larger species. Due to their low commercial value, smaller individuals are usually released alive. Wobbegong fins have no known commercial value. Historically, the attractive skin has been used as decorative leather (Last and Stevens 2009). However, it is unknown if this practice is still occurring.
The Western Wobbegong is a small component of the bycatch of the Western Australian temperate demersal gillnet and demersal longline fisheries, with the species more frequently observed than other smaller wobbegongs (for example, the Floral Banded Wobbegong, O. floridus and the Dwarf Spotted Wobbegong, O. parvimaculatus). The Western Wobbegong, along with other wobbegong species occurring within the region, is primarily caught by demersal gillnets off the southern and lower west coasts of Western Australia. A fisheries-dependent survey of southwest Western Australia fisheries reported that the Western Wobbegong constituted 1.4% and 0.9% of total elsamobranch catches from gillnet and longline gear, respectively (Jones et al. 2010). Wobbegongs were historically also caught by a few vessels using demersal longlines in the same fishery until the use of that gear was restricted in 2006. The Western Australian temperate demersal gillnet and demersal longline fisheries mean annual wobbegong catch was about 40 tonnes year-1 (range 28-68 tonnes) between 1999 and 2014 and does not show any sign of decline (Department of Fisheries Western Australia Fishery Status Report 1998-99 to 2013-14, for example, Braccini et al. 2014). Although wobbegong catches are generally not reported to individual species, small wobbegongs (<150 cm) are selectively discarded alive (Chidlow et al. 2007, R. McAuley, unpubl. data) due to low flesh recovery rates from smaller individuals. Thus, the Western Wobbegong is believed to be a minor component of those aggregated catches. In addition, post-release survival of wobbegongs is thought to be high.
Smaller wobbegongs also occur in commercial rock lobster pots throughout temperate coastal Western Australian waters (Chidlow et al. 2007). However, as all sharks and rays are now commercially protected throughout Western Australia, wobbegongs cannot generally be retained by State-managed commercial fishing vessels unless they are operating in the managed shark fishery.
The retained catch of wobbegongs by recreational fishers off the west coast of Australia has been estimated at approximately 1,000 animals year-1 (Sumner and Williamson 1999), while the estimated annual catch during 2011–12 by recreational fishing from boat licence holders was 1,535 wobbegongs, with 20% or 304 individuals retained (Ryan et al. 2013). Assuming the species composition of recreational wobbegong catches is similar to that of the commercial gillnet fishery, the Western Wobbegong is also likely to be a minor component of recreational catches.
All sharks and rays are commercially protected under Western Australian law. This regulation essentially restricts the retention of all shark and ray products by commercial fishing vessels other than those operating in the State's managed shark fishery. Retention of wobbegong bycatch by rock lobster vessels and trawlers is prohibited under Western Australian law. The likely small quantity of incidental Western Wobbegong bycatch is therefore believed to be discarded alive. Although not directly tested, observational evidence suggests that wobbegongs are a hardy group. Trap caught individuals can be released in good condition and post-release survival is presumed likely.
Relative to the area known to be occupied by the Western Wobbegong, shark fishing effort (mainly demersal gillnet) is sparsely distributed and managed via time-gear input controls. For example, the Metropolitan Fishing Zone, between Lancelin and south of Mandurah, was closed to commercial line and gillnet fishing in 2007 as part of a fishing reform package to ensure sustainability of fish for the future. The managed shark fishery's catches and fishing effort are also routinely monitored through analyses of statutory daily/trip logbook data and the fishery's target stocks are subject to regular stock assessments. The use of commercial shark fishing gear (large mesh gillnets and demersal longlines) is prohibited north of 26°30'S latitude to 120°E longitude off the north coast, which may include the northern extent of the species' range. The use of metal snoods (gangions) is commercially prohibited throughout Western Australian waters (except for a small amount of demersal longline effort in the managed shark fishery and pelagic mackerel troll lines). Recreational fishers are subject to a daily bag limit of two sharks per person.
Site attached species such as wobbegongs may also benefit from habitat protection and suitably designed and implemented no-take zones, where all forms of harvesting or fishing are excluded (Huveneers et al. 2006, Lee 2014). This species is potentially protected in the following Australian marine protected areas, marine parks and nature reserves:
Ningaloo Marine Park, WA
Shark Bay Marine Park, WA
Jurien Bay Marine Park, WA
Hamelin Pool Marine Nature Reserve, WA
Shoalwater Islands Marine Park, WA
Marmion Marine Park, WA
|Citation:||Huveneers, C. & McAuley, R.B. 2015. Orectolobus hutchinsi. The IUCN Red List of Threatened Species 2015: e.T42717A68638402. . Downloaded on 08 February 2016.|
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