Gulf wobbegong
| Gulf wobbegong | |
|---|---|
 | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Division: | Selachii |
| Order: | Orectolobiformes |
| Family: | Orectolobidae |
| Genus: | Orectolobus |
| Species: | O. halei |
| Binomial name | |
| Orectolobus halei Whitley, 1940 | |
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| Range of the gulf wobbegong (also off Flinders Island)[2] | |
The gulf wobbegong (Orectolobus halei) is a mid-sized species of predatory carpet shark with the varied coloration, striking patterning and distinctive morphology typical to the family Orectolobidae; it is native to the Southern Ocean where it inhabits the benthic zone.
Range
[edit]Endemic to Australian waters, the gulf wobbegong is found along interconnected coastal and reef regions spanning across the southern coast of the continent and beyond, ranging from Hervey Bay, Queensland, south to off Flinders Island (Bass Strait), Tasmania, and west to Norwegian Bay, Western Australia. [3]
Habitat
[edit]Orectolobus halei inhabits the coastal and inshore zone on the continental shelf from surface level to a depth of 95m–100m[4] (≈ 312'–328'). Bays and around offshore islands macroalgal-covered reefs, coral reef lagoons and reef flats as well as reef faces and reef channels, provide shelter where it settles on the sea floor and among structures such as caves, trenches, under ledges, and on large sponges. [3]
Biology
[edit]The adults of most wobbegong species ranges in growth from 117cm (3'10")[2] to 300cm (9'10") in total length (TL). Adult gulf wobbegongs grow to at least 206cm (6'9") TL, with sexual maturity occurring at around 16 years of age when females are 160–187cm (5'3"–6'2") TL and males, 168–181cm (5'6"–5'11") TL.[4] A 206cm (6'9") TL female has an estimated weight of about 62 kg based on the female length–weight relationship reported by Huveneers, et al. (2007)[5] As a lecithotrophic (ovoviviparous) species, O. halei birth from 17–47 pups following a 10–11 month gestation.[4] The neonatal sharklets are approximately 30cm (12") TL;[5] the weight of eight fully developed pups at 27cm (10"–11") TL, examined shortly before birth in a 2011 study, was found to be about 141g each.[6]
Ecology
[edit]As with other wobbegong sharks, O. halei is a nocturnal ambush predator with exceptional camouflage; they can be found resting during daylight hours and [3]hunt a variety of small bony and cartilaginous fishes at night.[4] A quantitative diet study identified 151 prey items of larger O. halei specimens which had been caught in commercial fishing nets; among the prey species was yellowtail scad, blue mackerel, eastern blue groper, mulloway, Port Jackson shark, and Orectolobus ornatus, the ornate wobbegong.[7]
Strong evidence for social association within the genus has been observed. A 1991 dive survey provided early evidence of site attachment, with individual wobbegongs observed in exactly the same positions on consecutive dives.[8] At Fish Rock, New South Wales, subsequent acoustic-telemetry research documented site fidelity in O. halei, with three of seven tagged sharks regularly detected at Fish Rock and the longest-resident individual detected nearly two years after tagging.[9] Further south at Cabbage Tree Bay Aquatic Reserve near Sydney, a 2016 study of spotted wobbegongs (O. maculatus) found non-random, temporally persistent associations between particular conspecifics; range overlap did not strongly explain the associations, providing evidence of social preferences rather than aggregation being solely a consequence of shared habitat.[10]
Due to pattern and coloration similarities, the identities of Orectolobus halei and Orectolobus ornatus were conflated for decades: O. halei was described as a subspecies of O. ornatus in 1940 and subsequently synonymized with it, before being elevated to species status in 2006.[11] Comparative genetic analysis, however, indicates that O. halei is more closely related to the largely sympatric spotted wobbegong, Orectolobus maculatus, than either are to the generally more northern O. ornatus. This relationship makes behavioral findings documented in O. maculatus potentially relevant to understanding social behavior in O. halei.[12]
Wobbegongs are shown to exhibit a notable response to intrusion into their domain. Although generally described as unaggressive when undisturbed, historical and modern accounts document wobbegongs leaving the bottom to advance toward an intruder in the water column, including instances wherein the shark swims up from the seafloor or shelf, approaching a diver or surfer in a possibly agonistic response.[13] Such records span historical taxonomic treatments in which species identities were not always equivalent to those used today, so they are best treated as genus-level behavioral data rather than as reliable evidence for any particular modern species.[13]
Taken together, these observations suggest that wobbegong populations are more behaviorally structured than a simple aggregation of individuals sharing suitable habitat. Individuals have been documented to show persistent attachment to particular locations, maintain non-random associations with conspecifics and respond selectively to intrusion into a range of space approaching their occupied site. This combination of spatial and social relationships may be viewed as a population matrix rather than merely a coincidental assemblage of animals.
Etymology
[edit]The common name “wobbegong” is derived from an Australian term native to the New South Wales region and has been recorded in English since 1852.[14]The gulf wobbegong, Orectolobus halei, is named in honor of Australian naturalist Herbert Mathew Hale (1895-1963)[15], researcher, field zoologist and natural-history collector of considerable standing, who became director of the institution that held and studied Australian zoological material, the South Australian Museum, from 1931 to 1960.[16]
Conservation status
[edit]As of October 31, 2021, O. halei has been categorized as Fully Recovered by the IUCN.[17]
References
[edit]- ↑ Huveneers, C.; Pollard, D.A.; Gordon, I.; Flaherty, A.A.; Pogonoski, J. (2015). "Orectolobus halei". IUCN Red List of Threatened Species. 2015 e.T161709A68638176. doi:10.2305/IUCN.UK.2015-4.RLTS.T161709A68638176.en. Retrieved 9 January 2025.
- 1 2 Marsh, N. (2007/08). Wobbegong Update... Archived 2011-07-23 at the Wayback Machine Sportdiving 125: 66-68.
- 1 2 3 Bray, D. J. (2019). "Gulf Wobbegong, Orectolobus halei (Whitley 1940)". Fishes of Australia. Retrieved 16 August 2026.
- 1 2 3 4 McGrouther, Mark (10 October 2022). "Gulf wobbegong (Orectolobus halei)". Australian Museum. Retrieved 16 August 2026.
- 1 2 Huveneers, Charlie; Otway, Nicholas M.; Harcourt, Robert G. (2007). "Morphometric relationships and catch composition of wobbegong sharks (Chondrichthyes: Orectolobus) commercially fished in New South Wales, Australia". Proceedings of the Linnean Society of New South Wales. 128: 243–249.
- ↑ Huveneers, Charlie; Otway, Nicholas M.; Harcourt, Robert G. (2011). "Quantification of the maternal–embryonal nutritional relationship of elasmobranchs: case study of wobbegong sharks". Journal of Fish Biology.
- ↑ Huveneers, Charlie; Otway, Nicholas M.; Gibbs, Susan E.; Harcourt, Robert G. (2007). "Quantitative diet assessment of wobbegong sharks (genus Orectolobus) in New South Wales, Australia". ICES Journal of Marine Science. 64 (6): 1272–1281. doi:10.1093/icesjms/fsm111.
- ↑ Ecology Lab (1991). A preliminary survey of grey nurse sharks (Carcharias taurus) and wobbegong sharks (Orectolobus spp.) at Seal Rocks, NSW (Report). Balgowlah, New South Wales, Australia: The Ecology Lab Pty. Ltd.
- ↑ Huveneers, Charlie; Otway, Nicholas M.; Stevens, J. D. (2007). "Observations of localised movements and residence times of wobbegong sharks (Orectolobus halei) at Fish Rock, NSW, Australia". Cybium. 31 (4): 403–410.
- ↑ Armansin, N. C.; Lee, K. A.; Huveneers, C.; Harcourt, R. G. (2016). "Integrating social network analysis and fine-scale positioning to characterize the associations of a benthic shark". Animal Behaviour. 115: 245–258. doi:10.1016/j.anbehav.2016.02.014.
- ↑ Huveneers, C. (2006). Redescription of two species of wobbegongs (Chondrichthyes: Orectolobidae) with elevation of Orectolobus halei Whitley 1940 to species level. Zootaxa 1284: 29-51.
- ↑ Corrigan, S.; Huveneers, C.; Schwartz, T. S.; Harcourt, R. G.; Beheregaray, L. B. (2008). "Genetic and reproductive evidence for two species of ornate wobbegong shark Orectolobus spp. on the Australian east coast". Journal of Fish Biology. 73: 1662–1675.
- 1 2 Compagno, Leonard J. V. (2001). Sharks of the World: Bullhead, Mackerel and Carpet Sharks (Heterodontiformes, Lamniformes and Orectolobiformes) (illustrated, revised ed.). Food and Agriculture Organization. pp. 155–157. ISBN 92-5-104543-7. Retrieved 2019-01-29.
- ↑ "Wobbegong". Merriam-Webster. Retrieved 17 August 2026.
- ↑ Christopher Scharpf & Kenneth J. Lazara (22 September 2018). "Order ORECTOLOBIFORMES (Carpet Sharks)". The ETYFish Project Fish Name Etymology Database. Christopher Scharpf and Kenneth J. Lazara. Archived from the original on 12 May 2016. Retrieved 17 January 2022.
- ↑ Kemper, Catherine. "Big, baffling and bounteous: The marine mammal collection at the South Australian Museum". reCollections: Journal of the National Museum of Australia. 11 (1). Retrieved 17 August 2026.
- ↑ Huveneers, C. (2021). "Orectolobus halei (Green Status assessment)". IUCN Red List of Threatened Species. 2021 e.T161709A16170920213. Retrieved 15 January 2022.