Common name(s)
Spotted Wobbegong.
Identification
A large species of wobbegong. Long nasal barbells; branched with 2 shorter dermal lobes. 6-10 pre-orbital dermal lobes, split into three groups. Two post-spiracular lobes with broad bases and short branched tips.
Two equally sized dorsal fins. First dorsal origin over pelvic fin insertion.
No warty tubercles on head or body. Body light brown with dark brown saddles and light brown circles edged with small pale spots. Some individuals are much darker than others.
Size
Maximum verified length 170cm. Reports of 320cm individuals are probably exaggerations. Size at birth approximately 20-25cm.
Habitat
Tropical and temperate seas. Found on rocky and coral reefs, seagrass beds, estuaries, tide pools, and on sand. Intertidal down to at least 218m.
Distribution
The spotted wobbegong is an Australian endemic. It is found on the east coast from Gladstone in Queensland, southwards, along most of the south coast, and on the west coast as far north as Bessieres Island off of Western Australia. It is absent from Tasmania and from the mainland opposite Tasmania.
Conservation Status
LEAST CONCERN
The Spotted Wobbegong is a biologically sensitive 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. In New South Wales, wobbegong catches combining all fishing methods and fisheries declined by more than 50% between 1997-1998 and 2007-08 after which it stabilized to around 20 tonnes. This led to all three species of wobbegongs occurring in New South Wales, including the Spotted Wobbegong, being regionally listed as Vulnerable in New South Wales. However, fishing effort reported as the number of days fished also declined between 1990-91 and 2008-09, resulting in catch rate being relatively constant around 15 kg per fishing day from 1990-91 until 2009. Fishing effort and ensuing catch rate should, however, be used with caution because it is coarsely reported as the number of days fished and does not account for the number of hooks used or soak times. 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. New management regulations in May 2008 introduced a daily limit of six wobbegongs. A minimum size limit of 130 cm total length for the Spotted Wobbegong implemented between 2008 and 2013 protected juveniles. Although the minimum size limit is no longer applicable, wobbegongs are no longer targeted to the same extent as they used to because of the trip limit implemented in 2008. In addition, further investigation of the New South Wales fishing catches and effort revealed that the catch per unit effort did not decrease as thought in the previous assessment. Wobbegongs are not targeted and catches are low in other Australian states (Western Australia, Queensland, South Australia, and Victoria). As a result, there is no evidence to infer or suspect population decline of the Spotted Wobbegong, and current catches are relatively low, resulting in a listing of Least Concern.
Citations and References
Huveneers, C., Pollard, D.A., Gordon, I., Flaherty, A.A. & Pogonoski, J. 2015. Orectolobus maculatus. The IUCN Red List of Threatened Species 2015: e.T41837A68638559. https://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T41837A68638559.en. Downloaded on 03 January 2021.
Reproduction
Ovoviparous and lecithotrophic, i.e. the foetus is solely nourished by the yolk within the egg case. Up to 37 pups per litter. Gestation lasts approximately 10-11 months with parturition occurring during September-October (Huveneers et al. 2007).
Diet
The spotted wobbegong feeds on bony fishes, elasmobranchs, and benthic invertebrates.
Wobbegongs are ambush predators that remain motionless, camouflaged against the reef. When an appropriately sized fish swims in front of its disguised mouth, the wobbegong lunges forward simultaneously stretching its mouth open. The process sucks water and the fish into its mouth, which immediately snaps shut again, trapping its prey with needle-like teeth.
Behavior
Nocturnal. Sometimes rests/hunts in water barely deep enough to conceal it. The spotted wobbegong has been observed partially exiting the water, using its powerful pectoral fins to drag itself from one tide pool to another.
Reaction to divers
Easy to approach. Remains at rest, relying on camouflage unless closely harassed.
Diving logistics
The spotted wobbegong is a commonly encountered species, especially in New South Wales and southern Queensland. Two particularly good spots where this species is easy to find are Fish Rock near the town of Southwest Rocks, and Julian Rocks in Byron Bay.
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Similar species
Cobbler Wobbegong has large tubercles on both the head and body that are not present in any other members of the family Orectolobidae.
Banded Wobbegong Distinguished by more intricate markings including dark saddles that are edged with broken black lines.
Western Wobbegong Distinguished by slender unbranched post-spiracular dermal lobes, and a yellowish brown coloration with well-defined, darker brown saddles containing paler markings that lack whitish rings and blotches.
Floral Banded Wobbegong Distinguished by predominantly dark brown coloration with clusters of white spots that form flower-like patterns.