Ornate wobbegong  (Orectolobus ornatus)

Classified as Near Threatened (NT) on the IUCN Red List (1).

With beautifully elaborate colouration, flattened bodies and branched projections around the jaws, wobbegongs are among the most unusual and highly distinctive shark species (3) (4). The ornate wobbegong’s particular colouration pattern features broad, dark patches on the upperparts, with black, wavy borders, containing numerous light spots within. These patches are interspersed by lighter areas, also mottled with a multitude of dark spots with light centres (5). Overall, the upperparts are golden-brown, and the underparts are pale (3). The arrangement and shape of the fins of wobbegongs is uncharacteristic of sharks, with two dorsal fins set well back on the body, with the first dorsal fin located over the pelvic fins (5). The tail is long, with the anal fin set so far back that it appears to be the lower lobe of the caudal fin, which, in fact, only has an upper lobe (3) (6). The broad flattened head has two fleshy barbells hanging down from the snout, while on either side of the mouth there are several extra, slightly branched projections, known as dermal lobes, which resemble fronds of seaweed (3) (5). The large jaws contain two rows of long, fang-like teeth in the upper jaw and three in the lower jaw (5).

The ornate wobbegong is found in the western Pacific, around the coast of Australia (3). The most recent evidence has led to the ornate wobbegong being split into two distinct species. A smaller form, which retains the original name, ornate wobbegong (Orectolobus ornatus), and a much larger form described as the banded or gulf wobbegong (Orectolobus halei) (2) (7). The ornate wobbegong therefore occupies a much smaller distribution than previously thought, ranging from Port Douglas in North Queensland, south to Sydney (7). This species has also been reported to occur around Papua New Guinea, Indonesia and Japan, but these record have yet to be substantiated (1) (5).

The ornate wobbegong inhabits tropical inshore regions around coastlines and offshore islands, where it occupies alga-covered rocky bottoms and reef areas (5). It can be found from shallow surface waters to depths of 100 metres (1) (5).

A nocturnal, bottom-dwelling species, the ornate wobbegong rests during the day, in caves, under ledges formed by coral reefs, and in trenches (1) (5). At nightfall, this species commences hunting for its preferred prey of fish and marine invertebrates, such as octopi and cuttlefish (3) (8). The striking colouration of the body provides excellent camouflage amongst fronds of algae and coral, and enables this shark to employ a sit-and-wait ambush strategy. The barbels around the mouth are used as lures to attract prey, which when in range, is quickly snapped in the powerful jaws. While smaller prey is immediately swallowed whole, larger animals may be held in the jaws, sometimes for days, impaled on the fang-like teeth. Once dead, the prey can then be swallowed without a struggle (3).

The ornate wobbegong is an ovoviviparous species, which means that it produces eggs that develop and hatch internally, and therefore gives birth to live young. While inside the uterus, the embryos are initially nourished by the egg yolk sac, but once hatched receive additional nourishment from a nutrient-rich fluid produced by the lining of the mother’s uterus (3). After a gestation period of 10 to 11 months as many as 18, but usually between seven and ten, pups are born, each measuring around 20 cm in length (7). The young sharks reach sexual maturity at around 80 centimetres in length. (2).

The main threat to the ornate wobbegong is fishing, both as a result of being directly targeted and through being caught accidentally as bycatch. Although not previously considered to be of commercial value, the flesh is now highly regarded as a food, and the skin is sometimes used to make decorative leather. The most severe effects of fishing have occurred in populations around the east coast of New South Wales in south-east Australia, where combined historic catch data for both the ornate wobbegong and the spotted wobbegong, Orectolobus maculates, indicate a decline of over 60 percent between 1990 and 2000. Elsewhere, catch levels appear to low and stable, but will require monitoring to ensure that they do not become problematic. Like other sharks, the ornate wobbegong takes a relatively long time to reach sexual maturity and produces few offspring, hence it is vulnerable to overexploitation (1).

In order to manage wobbegong fishing in New South Wales, legislation has recently been implemented. The Ocean Trap and Line Fishery and the Lobster Fishery are now only permitted to take six individuals of ornate wobbegong per trip, which must each measure at least 180 centimetres in total length (9). Recreational fishers are also no longer permitted to retain wobbegong shark catches (7). Such measures should help to maintain the population by ensuring that juvenile sharks reach breeding age. Elsewhere, this species can be found in a number of marine protected areas, and therefore its survival looks optimistic (1).

View information on this species at the UNEP World Conservation Monitoring Centre.

To learn more about the conservation of sharks and rays visit:

• Save Our Seas Foundation:
  www.saveourseas.com
• IUCN Shark Specialist Group:
  www.iucnssg.org
• Shark Research Institute:
  www.sharks.org
• Shark Trust:
  www.sharktrust.org