The Safina Center

May 8th
2014

Shark Tagging, Bahamas – Part 3

Blue Ocean Institute Fellow Dr. Demian Chapman, is leading a scientific research expedition in the Bahamian Shark Sanctuary. Chapman’s team is conducting groundbreaking research on the movements and behavior patterns of different shark species in an attempt to better understand and protect them.

Christine O’Connell, a science communicator at the Alan Alda Center for Communicating Science at Stony Brook University, is part of Chapman’s team and is blogging about their experiences from the Bahamas.

Read on and stay tuned for dispatches from the field!

panoramic-mangroves

THE BERRIES – PART 1

April 26, 2014, Christine O’Connell

The past 2 days we spent at the Berry Islands – a small, relatively uninhabited patch of islands in the Bahamas. The water here looked like a patchwork of aqua blue and emerald green stained glass. You could see straight down to the bottom. In the distance, the ocean just seemed to melt into the sky. The berries have lots of nooks and crannies, lined with mazes of mangroves that open up into shallow lagoons – perfect habitat for juvenile sharks.

The mangroves were teeming with wildlife: ibis and osprey flying overhead, manta rays and sting rays gliding through the water, little bait fish schooling beneath us, bigger fish like grouper and barracuda trolling the mangrove edges looking for a meal, and heaps of sea turtles darting back and fourth through the canals. The mangroves are quite the hangout place and lots of different animals use them as nursery grounds, including lemon sharks.

Shadows of the team working on the boat with mangroves in background.

Shadows of the team working on the boat with mangroves in background.

Mangroves and shallow lagoons. The dark areas in the water are sea grass beds.

Mangroves and shallow lagoons. The dark areas in the water are sea grass beds.

We caught and tagged three lemon sharks on Wednesday. We would have had four but one snapped the line. I caught a newborn lemon, it was around 2 feet long and only about one month old! In contrast, Mark caught one of the biggest lemons of the day – over 5 feet, and probably a few years old. As you can imagine, the smaller sharks are much easier to handle, but you still have to be really careful.

When working with sharks, you don’t just have to worry about getting bit, but also getting smacked by the tail (which packs a punch). And, if the shark’s skin scrapes against you fast in the wrong direction, you’ll end up with rug burn. A shark’s “skin” is made up rows of microscopic tooth like scales that lay flat against its body. If you move your hand from the tip of the nose to the tail, it feels smooth and leathery, but if you move your hand back the other way, it pushes up against the scales and feels like sandpaper.

Christine with a lemon shark.

Christine with a lemon shark.

To make the shark more comfortable while the team is taking their measurements, Mark gently turns the shark on its back with its white belly exposed to the sky. This puts the shark in a meditative state called “tonic.” It also makes it easier for us to work with the shark.

Mark putting a lemon shark in “tonic.”

Mark putting a lemon shark in “tonic.”

The DNA samples we take from the sharks are being analyzed by Kevin Feldheim, from the Pritzker Lab at the Chicago Field Museum. Kevin was on the first leg of this trip on Grand Bahama Island. So far, members of the team have shown that, although all the same species, there are genetically independent populations of sharks on different islands in the Bahamas. They have seen genetic differences in species as little as 150 km apart (about 93 miles or the distance from New York City to Philadelphia). This means there is surprisingly small-scale genetic structure in lemon sharks, a finding that is unprecedented in shark research. This also means you have to manage sharks on a fine scale. The more places/samples we get – the better the resolution of this genetic diversity.

2-islandscove________________________________________________________

THE BERRIES – PART 2

April 26, 2014, Christine O’Connell

sunrise-3

We started the day early and spent the morning at a location Mark named Pink House. It’s a beautiful spot nestled behind some small islands with shallow flats and filled with mangroves. A baby lemon shark paradise. Last year they caught 8 sharks at this site.

Sunrise at the Pink House.

Sunrise at the Pink House.

We put out the chum crate and cast out our lines. After a while, we ended up hooking a decent size male lemon shark. Mark pulled it along side the boat and I took the DNA sample. I got to put the tag in on this one, which was really exciting. The tag goes right at the base of the dorsal fin, so it is out of the way and doesn’t interfere with the shark at all. The skin around the tag heals up quickly, similar to an earring in the lobe of your ear, and stays with the shark as it grows. We take note of the tag number. If the shark is ever caught, either by a fishermen or a researcher, they will (hopefully) call in the tag number to a special hotline and the team can track the shark’s growth and movements.

Mark and Christine tagging a lemon shark. Photo credit: Sean Williams.

Mark and Christine tagging a lemon shark. Photo credit: Sean Williams.

As we were finishing up, the fishing line on the back of the boat started getting pulled out really fast. We hooked another! I jumped up and ran over to it. This one was a struggle to reel in. I stayed with it – pulled the rod tip up slowly when it pulled back, and lowered the rod tip down and reeled in fast when the line went slack. By the way it was pulling, I thought this shark would be a good size. However, as I reeled it in closer, I soon realized that it wasn’t a shark on my line at all, but a huge (for my standards) mutton snapper instead.

Christine and the 8 pound mutton snapper she caught.

Christine and the 8 pound mutton snapper she caught.

We spent a few more hours at various spots in the cove. We caught a small nurse shark, but released it right away. Nurse sharks are actually doing quite well and are not targeted by fisheries, so they are not part of this study. There was another lemon that kept coming close to us, but never took the bait. We gave up around noon and headed back to the boat.

Shark research takes a lot of patience, knowledge and skill. I was lucky to be able to learn from some of the best shark researchers out there. All and all, the team has tagged about 70 sharks over the past 2 years!

Mark and Sean on the bow of the boat.

Mark and Sean on the bow of the boat.

We left the Berries and headed to Nassau to drop me off (back to NY sadly) and pick up more team members for the Cat Island section with the oceanic whitetips. I’m sad to miss this leg of the trip, but will keep in touch with the team and continue to give updates from the field over the next few weeks – so stay tuned!

Sean sitting at the bow of the boat as we took off in the morning.

Sean sitting at the bow of the boat as we took off in the morning.

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Posted in:   Research, Sharks

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