A SWELL LITTLE AUSSIE SHARK
The
catshark family comprises over one hundred species and is the largest family
group of any shark. Australian waters host a rich population of catsharks, with
over thirty species so far recorded. But most of these catsharks live in deep
water and are rarely seen by divers. The one exception is the draughtboard shark
(Cephaloscyllium laticeps).
The
draughtboard shark reaches five feet in length and is reported to be one of the
most common sharks encountered in the temperate waters of southern Australia.
This shark is found in depths from 20 ft to 200 ft off the states of Victoria,
South Australia, southern New South Wales, southern Western Australia and
especially Tasmania.
The
draughtboard shark is named for its skin coloration, thought by someone to
resemble a draughtboard. They must have had a draughtboard made by surrealist
painter Salvador Dali, as this shark is gray to brown in color with a very
irregular pattern of darker blotches and spots, nothing like any draughtboard I
have seen. Over the years the draughtboard shark has also attracted a number of
other interesting and not very flattering common names, such as sleepy Joe, rock
shark, nutcracker shark and my favorite, flopguts.
Like
several other members of the catshark family, the draughtboard shark has the
ability to swell its body, by swallowing water to inflate its stomach, hence the
nickname flopguts. It is thought that these sharks swell so they can wedge
themselves in tight crevasses, making it difficult for potential predators (such
as seven gill sharks and possibly wobbegongs, octopus and seals) to remove them.
They may also swell to make themselves look bigger, to scare off any potential
predators.
Fascinated
by the draughtboard shark’s ability to swell, I had hoped to encounter one
when I regularly dived southern New South Wales in the eighties, but never found
one. I also didn’t find any when I did a dive trip around the Victorian
coastline in the early 1990s. So much for them being common. Local divers I
spoke to said they see draughtboard sharks, but only occasionally.
Melbourne
diver and photographer, Alan Beckhurst recently provided me with some very
helpful information about draughtboard sharks in Victoria. “While they are
common, they are usually tucked away in ledges and caves during the day, so not
often seen. We see lots of Port Jackson sharks, and almost as many seven gill
sharks as draughtboard sharks. But, we have a dive site where we often have a
four foot female follow us around, especially if we bring food.” Alan informed
me.
Determined
to see and pho
tograph
a draughtboard shark I headed down to Tasmania in 1992. I spent a wonderful week
diving Bicheno, with the Bicheno Dive Center, which offers some of the best
temperate water diving in the world. The water was cold, for a Queensland based
diver use to tropical water, however the diving was simply stunning,
unbelievable sponge gardens, a maze of caves, thick kelp beds, abundant fish
life and many colorful invertebrate species. I was diving in late summer, when
the water is a little warmer at 61F, but not as clear, only 30 ft to 50 ft
visibility, due to algae blooms. In winter the water temperature is a chilly
46F, but is crystal clear, with 100 ft plus visibility.
On
almost every dive I found draughtboard shark eggs, oval shaped cream colored
eggs, with distinctive horizontal grooves. There were draughtboard shark eggs
everywhere, attached to sponges and kelp by long tendrils. Shining a torch
behind each egg I could clearly see the yoke inside, but no embryos, evidence
the eggs were freshly laid.
Until
recently little research has been done on draughtboard sharks, however while
researching this article I was lucky to discover that Cynthia Awruch has just
completed her thesis on draughtboard sharks for the University of Tasmania.
As
little has been published on the draughtboard shark, Cynthia was able to shed a
little light on the breeding cycle, biology and behavior of this species. Like
other species of catsharks the males have larger teeth than the females, to
assist with mating when the male bites the female’s thick skin before
inserting a clasper. “Females lay eggs all year round. They lay two eggs every
twenty days over summer and every thirty days over winter. We found in captivity
that it takes around a year for the eggs to hatch” said Cynthia. The young
draughtboard sharks are around six inches long when they emerge.
After
a dozen brilliant dives off Bicheno I had seen plenty of draughtboard shark
eggs, but none of the creatures that laid them.
On
my last day we headed to a dive site called The Maze, a jumble of boulders
covered in kelp and sponges. Just when I thought I was never going to see a
draughtboard shark one suddenly swam into view. The 3 ft long shark was swimming
amongst the kelp and heading towards me. With my heart racing I lifted my camera
to capture some photos. The shark was getting closer and closer, just about in
camera range when it changed direction and darted off. I decided to give chase.
Finning
as hard as I could, these sharks are reported to be very slow swimmers, I
started to catch up with the shark, but with a flick of its tail the shark
disappeared into the kelp, and with it my last chance of getting a photograph of
a draughtboard shark. Well, at least I had seen one.
I
didn’t get to return to Tasmania until December 2005, this time doing three
days of diving at Eaglehawk Neck, with Eaglehawk Dive Center. This is another
spectacular temperate water dive destination. Kelp forests, sponge gardens,
massive sea caves and magnificent marine life make for some magic diving.
With
only three days of diving I didn’t like my chances of seeing a draughtboard
shark, but was going to enjoy the diving anyway. My first dive was at Nobbies
Wall, a dive site featuring gutters, a small drop-off and abundant reef fish and
invertebrate life.
Towards
the end of the dive as my wife, Helen, and I were heading back to the anchor a
draughtboard shark swam out of the kelp in front of us. I thought here we go
again, this shark is just going to swim off. However, much to my delight the
small shark swam straight up to us, stopped and settled in the kelp. I
couldn’t believe my luck.
For
the next five minutes this 3 ft long swell shark was the perfect model, sitting
amongst the kelp I got to photograph it from every angle and also closely study
it. I was curious to see if it would swell if picked up, so gently reach out and
grabbed the shark. The shark didn’t seem to mind being handled, sitting limply
in my hands. I turned it over, finding out it was a male, and also checking out
its tiny teeth, which it uses to feed on small fish, squid, crustaceans and
especially crayfish.
After
a minute the shark decided it didn’t like being closely scrutinized, and tried
to twist around and bite me. It couldn’t have done much damage with its small
teeth. At no time did it swell up. Other divers I have spoken to have seen
draughtboard sharks swell, and Cynthia informed me “They definitely swell when
they get stressed and take a long time to stop the swell once they start.”
Obviously I was not much of a threat.
I
let the small shark go and it calmly settled into the kelp once more. By now we
were getting quite cold and low on air, so left the shark to return to the boat.
The
next day we dived th
e
famous Fortescue Bay kelp forest, one of the few remaining kelp forests in
Tasmania. This was my first dive in a giant kelp forest and it was a magical
experience having a dark swaying canopy above.
Only
a few minutes into the dive we found a 4 ft long draughtboard shark sitting on
the bottom. I took a number of photos before the shark got bored of the
attention and swam off. A few feet away was another draughtboard shark. This one
was a little shy and swam off as soon as I got close to it.
After
seeing another draughtboard shark, only from a distance, on the next dive I had
to admit that these sharks appeared to be very common to this area of Tasmania.
I was surprised to find them so active during the day, as they are reported to
be nocturnal feeders.
While
researching draughtboard sharks, Cynthia Awruch found that these sharks are more
active at night, hunting for prey, and often spend a lot of time in the same
spot, sometimes days, which maybe associated with digestion. “They tend to
have some site fidelity, staying around the same area, although they can move
long distances. We found sharks moving from southern Tasmania to Flinders Island
(in Bass Strait), around 190 miles” Cynthia added.
Karen
Gowlett-Holmes, a marine biologist, underwater photographer and part owner of
Eaglehawk Dive Center, informed me that they regularly see draughtboard sharks
around the local reefs and even in caves. All of the sharks they encounter are
over 3 ft in length, they never see juvenile sharks, which possibly shelter in
deep water or hide in caves.
I
am already planning a return trip to the cool waters of Tasmania to find more
draughtboard sharks and hopefully photograph an elusive juvenile. But I am also
hoping to see one of these swell little Aussie sharks, swell.
Article appeared in Shark Diver Magazine No.15 Aug 2007