Common names
Western Wobbegong.
Binomial
Orectolobus hutchinsi.
Synonyms
None.
Identification
A fairly large species of wobbegong. Nasal barbells long with one short branch. Four short unbranched dermal lobes below or anterior to eyes and one unbranched post-spiracular dermal lobe.
Two equally sized, large dorsal fins. First dorsal origin over pelvic fin insertion.
No warty tubercles on head or body. Dorsal colour pattern consists of seven bold, dark brown saddles/bands with heavily corrugated edges separated by lighter pinkish-grey/brown areas. Pattern extends onto dorsal and cordal fins, but pectoral and pelvic fins mostly plain brown.
Size
Maximum verified length 149cm. Size at birth 22-26cm.
Conservation Status
LEAST CONCERN
The Western Wobbegong Shark is a minor bycatch in commercial gillnet and longline fisheries in Western Australia. Post release mortality is thought to be low.
However, in areas targeted by recreational spear fishermen, wobbegongs sightings are quite rare compared to areas where they are protected. Evidence of localized depletions are anecdotal, but spear fishing on scuba is popular at dive sites accessible from Perth so it is likely that wobbegongs numbers have declined in those areas.
Habitat
Tropical to temperate seas. The western wobbegong inhabits very shallow coral or rocky reefs from less than 1m to at least 106m.
Distribution
Orectolobus hutchinsi occurs over a relatively small range from Jerramungup on the south coast of Western Australia northward to Coral Bay.
Reproduction
Ovoviparous. 18-29 young per litter. Reproductive cycle every 2-3yrs. Age at maturity ~10yrs.
Diet
Diet consists mainly of bony fishes and octopuses.
Behavior
Rests by day under reef ledges. Wobbegongs are highly camouflaged ambush predators that lie in wait for an unsuspecting prey species to approach close enough for them to strike without swimming off the reef.
Reaction to divers
Difficult to find, but easy to approach. Remains at rest, relying on camouflage unless harassed.
CAUTION: Wobbegongs have been reported to have bitten divers that got too close to their mouths, even when not disturbed.
Diving logistics
The western wobbegong is widespread in Western Australia, but difficult to find at heavily dived sites. It is occasionally seen at Rottnest Island west of Perth and at other dive sites in the area accessible from the city, including on night dives at Cottesloe Beach. Divers at Cottesloe should avoid swimming at the surface because multiple fatal white shark attacks have occurred there.
The protected inshore reefs around Coral Bay may be the best place to find this species. This expansive area is best explored by boat, but swimming out from shore and searching under ledges can be productive. Beware of tiger sharks which are common on the area.
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Similar species
Northern Wobbegong – Orectolobus wardi Distinguished by smaller size, simpler pattern of dark blotches and less complex dermal lobes.
Gulf/Banded Wobbegong – Orectolobus halei Distinguished by large size, branching dermal lobes, and more intricate markings lacking saddles with corrugated edges.