Not just Shark
Pictures: Elasmodiver contains photos of sharks, skates, rays, and
chimaera's from around the world. Elasmodiver began as a simple web
based shark field guide to help divers find the best places to
encounter the different species of sharks and rays that live in
shallow water but it has slowly evolved into a much larger project
containing information on all aspects of shark diving and shark
There are now
more than 5000 shark pictures and sections on shark evolution,
biology, and conservation. There is a large library of reviewed
shark books, a constantly updated shark taxonomy page, a monster
list of shark links, and deeper in the site there are numerous
articles and stories about shark encounters. Elasmodiver is now so
difficult to check for updates, that new information and pictures
are listed on an Elasmodiver Updates Page that can be accessed here:
First published in
Shark Diver Magazine November 2009
The day after diving with silky sharks in Venice, we were
scheduled to accompany Dr Eric Hoffmayer on a shark sampling expedition in
the Mississippi Sound. Concerned that we would miss the boat, Claire and I
dodged New Orleans and raced east through the night.
As we approached Ocean Springs, the oppressive mugginess
erupted with a deluge heavy enough to send our camper skidding around each
greasy bend in the road.
We joked about putting on our dive gear while the torrential
rain, punctuated by a barrage of lightning bolts, hammered into the swamp
land around us. Some hits were close enough to throw tree branches into the
streets and I began to grow uneasy about the mountain bike, inadvertently
doubling as a lightning rod, strapped to the roof of our van.
I’m a little paranoid about lightning. A few years back, I
was struck while riding a bicycle across Grand Cayman. It was a glancing
blow that initially selected my right hand, pulling it skyward. Luckily, the
actual bolt of electricity barely touched me as it slammed into the road
next to me.
Trying not to think about that experience, we pushed on
towards town but eventually we were forced to take refuge under a gas
station awning while the storm front passed us by. Claire dozed in the back
and I sat staring out at the maelstrom wondering if all the run off would
ruin tomorrow’s chances of seeing sharks.
The next morning dawned clear. When we rolled up to the
research vessel the crew was busy loading bait and equipment. We introduced
ourselves to Dr Eric Hoffmayer who had graciously offered to let us tag
along with his team of researchers in order to document their work and
hopefully snap some images of Atlantic sharpnose sharks. Sharpnoses are
relatively common in the northern Gulf of Mexico but they are so small and
timid that divers never encounter them. We wanted to photograph a shark as
it was being released which is probbly the only way to get a good i.d. shot
of this particular species.
Bleary eyed from the previous night’s adventures, I sat and
listened to Eric talking about the relationship between sharpnose sharks,
water temperature, salinity and hypoxia. Far from the stiff professorial
demeanor that I had expected, Eric’s enthusiasm for sharks and willingness
to share his wisdom soon pulled me out of my mental haze.
He explained that male Atlantic sharpnose sharks migrate into
the sound in early summer. This roughly coincides with rising water temps
and dwindling freshwater outflow from the Mississippi Delta which leads to
an increase in near shore salinity levels. Although the sharpnoses push far
inshore they are relatively stenohaline - intolerant of brackish
environments. The low oxygen levels in the sound are also a problem for the
ram ventilating predators so the question that Eric would like to answer is
why the little sharks bother coming into the sound at all.
Female Atlantic sharpnoses usually stay in much deeper water
so the males are definitely not there to mate. There is a reasonably
abundant food supply but no more so that further out in the gulf and the
extremely warm inshore waters cause the sharks’ metabolisms to speed up so
much that they cannot consume enough food to keep up with their energy
requirements. Consequently, by the end of the summer they have used up all
of their energy reserves and their oil filled livers have shrunk to a third
of their original size. Fishermen call the emaciated post-summer sharpnose
There are three primary factors that influence the movements
of animals: food supply, reproduction and safety. Eric surmises that if it
isn’t about the food or mating and the environment is physiologically
detrimental to the shark’s health then they are probably migrating into the
sound to hide. Atlantic sharpnose sharks are an important prey species for
many of their larger cousins. Although bull sharks, blacktips and a number
of other sharks follow the sharpnoses into shallow water, the sound is
probably a far safer place for a 3ft shark than out in the clear, deep,
shark infested waters of the gulf.
Eric’s team set a long line with 100 baited hooks in 15ft of
rust colored water. The sound looked utterly uninviting but Claire and I
donned our suits anyway just incase Eric caught something for us to play
with. The line was left marinating in the muddy bay for an hour then slowly
reeled back in. The first few hooks came up bare but eventually a small
shark broke the surface and thrashed until its whole body weight was
suspended from the hook.
Jill Hendon (Eric’s assistant) quickly dehooked the shark and
took length and weight measurements and a fin clip for later DNA analysis.
Eric then inserted a spaghetti tag that contained information about his lab
and dropped the animal back into the soup.
This process was repeated each time a live shark came up but
that wasn’t always the case. Some came up disembodied from hungry but unseen
bull sharks and many of the landed sharks were simply DOA; victims of shark
research. I understand that this is a necessary evil in the collection of
scientific data but I couldn’t do it. Fortunately my job has no such
Eventually, Eric got a shark that was in great condition and
Claire and I jumped in with it when it was ready to be released. I did a
quick visibility check by holding out my arm and looking at my gloved hand.
The water quality was so poor that I could barely see past my elbow and my
hand was completely hidden. I soon realized that this was going to be
Claire was gently holding the 2ft sharpnose and on my signal
she released it right in front of me. I did my best to frame a few shots but
there was so much silt in the water that my camera wouldn’t autofocus. The
shark swam away and we climbed back onboard for a rethink.
The researchers laid a total of four sets over the next
couple of days and Claire and I played with different techniques to try to
capture some publishable images. It was a strange and stressful adventure,
not least because we could rarely see below our waists and we knew that
there were bull sharks milling around in the darkness below us.
Eventually it all worked out. Eric got some live Atlantic
sharpnose images to illustrate his research, I got a new species for my
field guide on Elasmodiver.com, Eli got this story for SDM and Claire got a
nervous twitch (not really).