WEIRD & WONDERFUL WOBBIES

The name wobbegong comes from an Aboriginal word meaning ‘shaggy beard’, which is a great description of one of the most common sharks a diver will encounter in the seas around Australia.
   Over the years I have found that divers either love or loath wobbegongs. This love/hate relationship is due to the fact that wobbies, unlike most sharks, are unafraid of divers and rarely move when a diver comes close. Plus wobbegongs are responsible for more non-fatal shark attacks (or more accurately bites) in Australia than any other shark species.
    Wobbegongs belong to the family Orectolobidae, and are represented by six described species and several undescribed species. These sharks are easily identified by their flattened bodies, their colourful camouflage skin patterns and by their dermal lobes, those shaggy beards around their heads. All species have a wide mouth and very long sharp teeth, which they use to great effect to catch prey.
   Wobbegongs are found in a variety of marine environments, from rocky reefs to coral gardens, and even on man-made structures, such as shipwrecks. Most species prefer a habitat with ledges and caves to shelter in, but larger wobbies are quite happy lying out in the open. Wobbegongs can be found in very shallow water to the continental shelf, in depths from 1m to 100m.

  AUSTRALIAN WOBBEGONG SPECIES

Rarely does a dive go by in many parts of Australia without encountering a wobbegong. Six recognized species of wobbegong are found around Australia, five of which are described. The only described species not found off Australia is the Japanese wobbegong (Orectolobus japonicus), which looks very similar to the ornate wobbegong.

Tasselled Wobbegong – Eucrossorhinus dasypogon

Of all the wobbegongs, the tasselled wobbegong would have to have the most cryptic of camouflages. It has a more flattened body than any other species, and its sandy brown colour allows it to blend in perfectly against coral rubble and between hard corals. It also has the most elaborate beard of dermal lobes, making it hard at times to distinguish the shark’s head.
   Found in tropical waters from Queensland and around the top end into Western Australia, the tasselled wobbegong is also found in Papua New Guinea and Indonesia. This shark is reported to grow to 3m in length, however animals over 2m long are rarely seen.
   Divers generally encounter this shark by accident for the first time, when they are looking under a ledge and come face to face with one or, as I have done, putting their hand on one when looking into a cave. I have always found them to be quite docile, but other divers give them a wide berth.
   The tasselled wobbegong appears to be a solitary animal, rarely do you find more than one sharing a cave. The most I have found at one site was six at a coral bommie off Fairfax Island, east of Gladstone. Though said to be common on the Great Barrier Reef, I have found them to be most abundant around the island and reefs of the Capricorn and Bunker Groups.

Spotted Wobbegong – Orectolobus maculatus

Growing to a maximum length of 3.2m, the spotted wobbegong is one of the top predators on the rocky reefs of southern Australia. This shark is found from central Western Australia through to southern Queensland, excluding Tasmania, although it appears to be most common off New South Wales.
   Spotted wobbegong vary in colour from sandy brown to dark chocolate brown, and have a covering of lighter rings and spots. Their colour range is quite varied, I have seen sandy white coloured ones lying out on the sand, and even yellow and orange coloured ones on shipwrecks. They tend to pick a bottom colour similar to their own body colour to assist with camouflage. Large specimens even have quite prominent darker bands and colouration, leading to confusion with the ornate wobbegong. The best way to distinguish between the two species is to count the dermal lobes, the ornate having around 14, the spotted around 20, including two closely grouped clumps of lobes on each side of the head.
   I have taken hundreds of photos of ornate and spotted wobbegongs, and still get confused identifying some darker coloured spotted wobbegongs. The darker colouration and bands only seem to occur on larger sharks, over 2m long, so they may possibly go through a colour metamorphosis once they reach a certain length.
   Very little is known about spotted wobbegong behaviour, from my experience they appear to have a home range. Diving the same patch of reef over a period of time, the same wobbies appear to be in the same caves. They are quite social, and up to a dozen can be seen sharing a cave, packed in close together and even lying on top of each other. They also share caves with ornate wobbegongs, Port Jackson sharks and brown banded catsharks.
   Divers see the greatest numbers of spotted wobbegongs off the northern New South Wales coastline, which has led to them being targeted in uncontrolled fishing, but more on that later. Julian Rocks, off Byron Bay, would have to be the best place to observe and photograph spotted wobbegongs. On every dive a couple of dozen can be seen, and some of them are huge, 2m to 2.5m long.

Ornate Wobbegong – Orectolobus ornatus

Ornate wobbegongs are found over much the same area as the spotted wobbegong, however their range extends right along the Queensland coast and into Papua New Guinea and Indonesia. They appear to be most prolific off northern New South Wales and southern Queensland, where dozens can be found on some reefs.
   As their name suggests, ornate wobbegongs have very ornately decorated skin, with the base colour being brown and patterned with corrugated bands and reticulation in a greyish colour. Ornate wobbegongs grow to 2.9m in length, but are rarely seen over 2m long. Like the spotted wobbegong, they are quite social and share caves and ledges.
   I have noticed quite a bit of difference between ornate wobbegongs found in southern Australia and northern Australia, and have for a long time suspected that there maybe two seperate sub-species. The northern species I have seen and photographed, have more elaborate patterns on their skin and are rarely grow over 1.5m long. While the southern species are much more drab in their colouration and generally grow larger. According to scientists, this species doesn’t reach sexual maturity until 1.8m long, however I have observed mature males and pregnant females less than a metre long.
   I have suspected for many years that ornate and spotted wobbegongs may inter-breed, as you see some that have features from both species, however until further research this theory cannot be proven.

Western Wobbegong - Orectolobus sp.

   Easily confused with the ornate wobbegong, the western wobbegong is smaller, only reaching 2m in length, and has fewer and shorter dermal lobes. This shark varies in colour from brown to yellowish brown, and has darker corrugated bands. It is only found in Western Australia, between Ningaloo Reef and Cape Leeuwin, where it appears to be the most abundant member of the family.
    Though known of for many years, the western wobbegong is still undescribed. Research on this species, conducted by Justin Chidlow, from the Western Australian Department of Fisheries, suggests that males and females reach sexual maturity when 1.1m in length, with the females only breeding every two to three years.

  Northern Wobbegong - Orectolobus wardi

   The northern wobbegong reaches a maximum length of 1m, though specimens around 60cm are more common. This shark is easily identified by its small size and by the limited number of dermal lobes on its head. Its colouration is the least elaborate of the family, a mottled brownish colour with darker bands. Though found off Queensland, Northern Territory and Western Australia, it appears to be most common in northern Western Australia, where divers find them around Ningaloo Reef. It spends most of its time in shallow water, however very little is known about its biology.

  Cobbler Wobbegong – Sutorectus tentacilatus

   The cobbler wobbegong is easily distinguished from other members of this family by the rows of tubercles (wart like bumps) along the back and head. Reaching a maximum length of 90cm, this species is found off South Australia and Western Australia, from Adelaide to Geraldton. It has quite short dermal lobes, except for the front two, which are very long. The cobbler wobbegong has a brownish base colour with lighter bands and spots.

WOBBEGONG DIET

During the day wobbegongs are most commonly observed lazing on the bottom, either in caves, under ledges, or out in the open. Even though they appear to be asleep, they are always ready to snatch a meal if the opportunity presents itself. Wobbegongs feed on fish, octopus, squid, small rays, and other sharks, such as blind sharks, Port Jackson sharks and even other wobbegongs. Forster diver Denis Kemp, once told me about a large spotted wobbegong he found in a cave at Taurus Reef off Forster, NSW. The huge shark had a small grey nurse shark in its mouth, which it slowly swallowed.
    It has long been thought that wobbegongs also eat crabs and crayfish, however a study on their diet by Justin Chidlow in Western Australia, found no evidence of crustaceans in their diet. A number of divers I have spoken to believe that there is a close link between wobbegongs and crayfish. Wobbegongs are occasionally found sharing a cave with crayfish, which are the favourite food of octopus. The over fishing of wobbegongs in New South Wales is thought to have caused a decrease in crayfish numbers, but an increase in octopus.
    Wobbegongs are ambush predators, and you can always tell when a wobbegong is looking for a feed as they lift their head off the bottom. While they will feed during the day, if the opportunity exists, they mainly feed at night, being far more active after dark. It is thought that wobbies actively stalk the bottom for prey at night.
    I wouldn’t recommend handfeeding wobbegongs as they are very unpredictable. I once found a dead mullet on the bottom at Shag Rock off Brisbane, and decided to feed it to a small ornate wobbegong. For several minutes I dangled the fish in the wobbegong’s face, with no reaction. Just as I dropped the fish in front of the wobbegong it lunged out grabbing most of the fish in its mouth. It took a lot more of the fish into its mouth than I anticipated, and would probably have bit my fingers if I had still been holding the fish.
    Once wobbegongs have a good feed they may not need to eat again for several days. In his research in Western Australia, Justin Chidlow found that many of the wobbegongs he examined had empty stomachs, and has suggested that once a wobbegong feeds it rests for a long period to aid digestion. Rob Carraro, during a study on ornate wobbegongs at Port Stephens, noticed that once a wobbegong had fed, it appeared to stay in one spot for up to five days.

WOBBEGONG REPRODUCTION

All wobbegongs are ovoviviparous, meaning they give birth to live young. Mating has been observed in captivity and the wild, with the male biting the female around the gill area and then lying beside her, the male then inserts one clasper. Research on the western wobbegong by Justin Chidlow, found that the sharks mate over winter, and the females may delay their pregnancy by storing sperm for up to six months.
    Simon Hartley, from Southern Cross University, was lucky enough to observe and photograph mating ornate wobbegongs at Byron Bay in August 1998. The sharks were quite small, a 84cm long male and 86cm long female, much less than the 1.8m size they were thought to attain before sexual maturity. The wobbies were already mating when Simon started to observe them, and they remained in their embrace for over 20 minutes. After parting Simon noticed that the male’s clasper was bent at the end to anchor it in position in the females cloaca. For more information on wobby mating refer to the Southern Cross University website - www.scu.edu.au/schools/rsm/staff/pages/shartley/projects/wobbies/mating.html
    I have never witnessed wobbegongs mating, but have observed hundreds of pregnant females, some so big they look ready to explode. Diving at Byron Bay in winter is a good time to observe pregnant wobbies, and a few years ago I thought I was going to witness a birth. I observed a pregnant ornate wobbegong swimming along the bottom rubbing her belly along the sand. I watched for several minutes as she swapped from side to side. After a while she settled on the bottom, unfortunately nothing else happened. This unusual behaviour may have been brought on by labour pains, as she appeared to have a swollen cloaca. Rob Carraro, in his research at Port Stephens, observed several seemingly pregnant ornate wobbegongs arching their backs and lifting their tails.
    The gestation period of wobbegongs is thought to be between nine to eleven months, with wobbies giving birth to litters that vary in number for one to forty. Recently, the Blackpool Sea Life Centre in England had a captive wobbegong give birth, with two pups emerged every 24 hours. This time delay may possibly give the young the best chance of survival, allowing them to disperse over a wider area, away from predators. The young are around 20cm long at birth and usually hide in crevasses to avoid getting eaten by larger wobbegongs and other predators.
    Rob Carraro observed a number of apparently pregnant females when studying ornate wobbegongs at Port Stephens. When watching one expectant mother, a larger male wobbegong swam into the crevasse beside the female and proceeded to nudge her stomach. The female gave a shudder and then the male snapped at something several times before it swam off. The whole incident lasted less than a minute, and Rob is almost certain a pup emerged and was eaten by the male!
    Though only 20cm long at birth, young wobbegongs are born ready to fend for themselves and should never be underestimated. Diving at Byron Bay with Tony Little a few years ago, we found a wobbegong pup only 25cm long. Tony had a macro set-up on his camera and decided to get some close-ups of the wobbegong’s head. Tony stuck the framer in the wobby’s face, which it didn’t appreciate, and informed Tony by biting the framer with all its might. After grappling with the framer for a few seconds the pup took off under a ledge. After the dive, Tony showed me his steel macro framer, which had a series of small indentations from the little pup’s teeth.

  WOBBEGONG ATTACKS

I am pretty certain that wobbegongs are responsible for more ‘shark attacks’ on divers in Australia than any other shark species. The International Shark Attack File only lists 18 attacks by wobbegongs, however most attacks must go unreported, as the diver is either too embarrassed, uninjured or couldn’t be bothered to report it.
    Wobbegongs are reported to be able to bite their own tail, however I wouldn’t recommend pulling ones tail to find out. Wobbies also move a lot quicker than people expect, giving divers little chance of moving out of the way if they really want to snap. I have been lucky never to have been bitten by a wobbegong, considering the number of times I have accidentally put my hand on one, or annoyed them for photos.
    Wobbegong attacks can be unprovoked, however I would say most attacks are provoked by the diver, willingly or unwittingly. If a wobbegong has its head raised off the bottom, it is looking for food, so if a divers hand, especially an ungloved one, comes near its head it will bite it. Wobbegongs are thought to have poor eye sight and are attracted to movement rather than shape. Also if you spear fish near a wobbegong expect some attention. I have heard stories of wobbegongs leaving the bottom to follow a speared fish, and the diver, all the way to the surface.
    You can’t really blame a wobby for biting a diver that pulls its tail, kneels on its head, pats its back or tries to hold it. Fortunately, most wobbegongs would rather not bite a diver, and either ignore them, swim off or give a warning snap, or bark, as a warning to back off. I have had dozens of wobbies snap at me when too close, and I always take the advice.
    The most spectacular snap I ever witnessed was at Byron Bay. Diving with local guide, Pete Murphy, at Julian Rocks, he was giving us a guided tour around Cod Hole. Swimming over a gutter we spotted a monster 3m long spotted wobbegong, with a head close to a metre wide. Pete decided he was going to pat this massive shark, so I just sat back to watch. As Pete reached out with his hand the wobby quickly turned towards him, opened its mouth wide and snapped its jaw shut just millimetres from Pete’s mask. This shark was big enough to have engulfed not only Pete’s head, but half of his torso. The wobby’s warning snap had the desired affect, with a very pale looking Pete quickly backing away.
    When a wobbegong bites it doesn’t like to let go. Their long dagger-like teeth are designed to grip prey, so they generally hold onto larger prey until it dies and can be swallowed whole. This is unfortunate for the unlucky diver that gets bitten, as the wobbegong can be difficult to dislodge. I have heard stories of divers returning to the dive boat with a wobbegong attached to their arm, leg and even buttocks. Most of the time the wobbegong will release its grip once it realises that it couldn’t possible swallow you and your tank, but sometimes the diver has to be patient. If the wobbegong insists on holding onto you, then you will have to wait for it to get bored or readjust its grip. When it readjusts its hold, you will have an opportunity to get free, if you’re quick!
    Though there is little chance of dying from a wobbegong attack, the bites can be quite nasty, especially if the diver isn’t wearing a wetsuit. The best advice I can give is not to harass wobbies.

  WOBBEGONGS UNDER THREAT

The flesh of wobbegong is quite tasty. Lacking bones, the flesh is commonly sold through fish and chip shops as fish pieces or fish cocktails. Wobbegongs have also been taken for their skin. Their elaborate skin patterns and colouration being tanned for a range of leather products.
    Until recently there was never a major fishery for wobbegongs in Australia, they were generally taken as by-catch from other fisheries. Around 40 tonnes annually are taken in just the southern and west coast gill-net shark fisheries. Then in 1988, professional fishermen in New South Wales started to target wobbegongs with drop-line fishing. To capture wobbegongs fishermen placed set drop-lines with a maximum of six baited hooks. The drop-lines were left unattended, sometimes only checked once a day. This fishing practise soon became very popular in New South Wales, with the professional fishermen using it to supplement other forms of fishing (wobbies are also captured in commercial ocean fish traps).
    They soon decimated the wobbegong population in many areas. In 1990/1991, 120 tonnes of wobbegong were landed in New South Wales. However, by 1999/2000 the catch had fallen to 40 tonnes. Not only were these fishermen wiping out wobbegongs, they also catching the protected grey nurse shark, most of which were killed by the fishermen to get rid of ‘unwanted competition’.
    In many areas, like Seal Rocks, the fishermen took so many wobbegongs that divers would rarely see one during a dive. Calls to ban drop-lining were ignored by the New South Wales Government, even though it was quite obvious that they were wiping out wobbegongs and grey nurse sharks.
    Though drop-lining continues today, the overfishing and greed shown by these fishermen has decimated the wobbegong population to such an extent that it is starting to become uneconomical to target wobbegongs. I contacted David Harasti, Conservation Manager of the Threatened Species Unit of the New South Wales Fisheries, who informed me that a large drop-line fishery for wobbegongs continues off Narooma and between South West Rocks and Seal Rocks.
    At the beginning of 2002, the New South Wales Fisheries released a discussion paper about the management of wobbegongs in the state. The paper reviewed wobbegong biology, listed all threats to the species, and listed a number of management options to conserve the species, such as bag limits, minimum and maximum sizes, protected habitats and seasonal closures. The New South Wales Fisheries received 75 submissions, with the most support shown for protecting critical habitat areas and size limits. Unfortunately, the New South Wales Fisheries have since done little to address the decline in wobbegong numbers. None of the recommendations of the discussion paper have been implemented, though a number of wobbegong sites have been protected from commercial fishing with the declaration of ten grey nurse shark critical habitat zones. Currently, the management of the wobbegong fishery in New South Wales, is being reviewed by the Ocean Trap and Line Fisheries Management Strategy.

  WOBBEGONG RESEARCH

Not a great deal of research has been conducted on wobbegongs, or sharks in Australia in general, due to little money being available for this work. However, with declining wobbegong numbers in New South Wales, due to fishing pressures, a number of research projects have been completed in the last few years.
    Justin Chidlow looked at four species of wobbegong captured in commercial shark fishers gill-nets in south-west Western Australia for his masters degree with James Cook University. Between February 1997 and May 1998, Justin collected data to better understand the biology of the western wobbegong, ornate wobbegong, spotted wobbegong and cobbler wobbegong. He looked at their diet, finding that crustaceans formed no part of their diet, growth rates and reproduction. Though wobbegongs are only a by-catch in Western Australia, Justin’s research concluded that wobbegongs, like all sharks, would be susceptible to overfishing if targeted in a commercial fishery, due to their low reproduction rate, slow growth rate and late sexual maturity.
    Simon Hartley of Southern Cross University, has been surveying the wobbegong population at Byron Bay dive sites since 1998. Over that time, with help from undergraduate students, he has collated some interesting information about the population of the spotted and ornate wobbegong. His preliminary research found that more females than males where observed throughout the year in both species. Why this sexual segregation is occurring is unknown, though Simon speculates that it could be linked to water temperature or depth.
    Another interesting factor that Simon discovered was the size difference between the two species. The ornate wobbegongs were most common in the 50cm to 100cm length range, while the spotted wobbegongs were in the 100cm to 150cm length range. The two species also preferred different habitats, the ornate found resting on corals or algae covered rocks, while the spotted preferred sandy bottoms. Simon believes this could be connected with the shark’s colouration, the ornate wobbegongs generally being darker in colour, the spotted wobbegongs lighter. For more detailed information about this research visit the Southern Cross University website - www.scu.edu.au/schools/rsm/staff/pages/shartley/projects/wobbies
   The decline in the wobbegong population in New South Wales also prompted Rob Carraro to study them at Port Stephens. In 2002 and 2003, Rob, for his honours degree at Newcastle University, tagged and photographed ornate wobbegongs at the Fly Point and Halifax Park Aquatic Reserve. Over a one hundred day observation period, Rob looked at the shark’s preferred habitat, the sex ratio, the size of the sharks and their movements within the reserve. The sharks preferred habitat depended on what was available at the site, sponge gardens at Fly Point, barren rocky terrain at Halifax Park and man-made structures at Little Beach. Unlike Byron Bay, the sex ratio favoured the males at two to one, except during December when it was one to one. Most of the sharks observed were less than 1.3m long, including a number of apparently pregnant females, with the area mainly inhabited by juveniles and immature adults.
    Rob identified 40 individual ornate wobbegongs, with 133 re-sightings. Most of the resighted sharks were seen in the same spot or area, with little movement between the areas surveyed. Few ornate wobbegongs were found in the surrounding areas outside the reserve, indicating the importance of protected areas in conserving wobbegongs. Rob also observed apparent breeding activity in April and May. Rob informed me that he would like to continue this research at Port Stephens, but a lack of available funding will make it difficult.
    Currently, Charlie Huveneers, a PhD student at Macquarie University, is studying ornate and spotted wobbegongs in New South Wales. Charlie’s research will look into the biology and ecology of both species. The data collected will hopefully allow better management of the current wobbegong fishery in the state. Divers are asked to become involved in this project by surveying wobbegong numbers, much like the grey nurse shark surveys. For information contact charlie.huveneers@gse.mq.edu.au
   Wobbegongs may be one of the most common sharks seen in the seas around Australia, and I for one hope they remain that way. However, if their numbers continue to dwindle from uncontrolled commercial fishing, encounters with shaggy beard sharks may become a rare privilege.

Article appeared in Sportdiving Magazine No.109 Apr/May 2005