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Shark Superhighway premieres Wednesday April 21 at 9P et/pt.

By Shark Superhighway Production Crew

The mood was heavy on board the ship that night.

The expedition to the Galapagos Islands to track hammerhead sharks had been going exceptionally well. The scientific team, led by renowned shark biologist Peter Klimley, was having great success locating schools of sharks and diving down to place tracking tags on them. These successes had buoyed their hopes of capturing a hammerhead and placing a long-range satellite-tracking device on its dorsal fin. But now, those hopes were sinking fast.

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The ship has been anchored in the far northern reaches of the Galapagos Archipelago at an ancient crumbling volcano called Wolf Island. This is one of the wildest and most electrifying dive spots on the planet, with sharks everywhere. It is a perfect place to study the movements of hammerheads, considered to be sophisticated ocean travelers with well-defined migration routes.

To practice their capture technique, the crew had sent a team of Ecuadorian fishermen out to hook a Galapagos shark and tow it back to the ship. The idea was then to pull the shark onto a sling, then use a crane to lift it onto the deck. Seawater would be pumped across the shark’s gills to keep it alive while the satellite tag was installed.

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That was much easier said than done. The shark fought back, thrashing about each time it was pulled toward the sling. And when the shark was pulled into position, the sling fell out of position. As the exhausted shark began to get pulled by currents whipping alongside the ship… the exhausted crew grew more and more frustrated. Finally, after re-organizing their technique, they managed to get the shark onto the deck. They installed the tag and let the shark go.

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The difficulty of capturing the Galapagos shark had underscored the risks involved in capturing a hammerhead. They are a type of shark known as a “ram ventilator.” This means they must always keep swimming forward to keep water moving over their gills. When these sharks are restricted, as when they are caught on long lines by fishermen, they frequently die. According to one shark scientist, they are like “high performance sports cars” compared to the much heartier Galapagos sharks’ SUV.

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A wave of conflicting pressures was beginning to wash over the expedition. The local fisheries industry had been forbidden from catching sharks in the Galapagos Marine Reserve. Meanwhile, the local dive industry worried that shark populations were dropping. If a shark were to be harmed in the name of science, a scandal could erupt. And now, the crew faced the chance that they wouldn’t even get a chance. As Dr. Alex Hearn, a team member from the Charles Darwin Research station, told us: “We’ve tried on two previous cruises and it just seems like you could drop a hook into a school of 200 hammerheads and you’ll catch a Galapagos shark.”

The crew called the fishermen into a meeting to impress on them the importance to the expedition of catching a hammerhead. They also discussed the hammerhead diet in hopes of being able to attract them with the right bait. Newly motivated, the fishermen set out at night with underwater lights hoping to catch some squid.

When morning arrived, the underwater lights were on the ship’s deck. A member of the ship’s crew reported that they had returned empty handed, but had gone out again. The scientists began to accept that their dream of tracking a hammerhead over the coming months and years via satellite was dying.

Then a radio call came in to the ship’s captain. The fishermen had hooked a hammerhead, and they were towing it back. The fog suddenly lifted, and the crew swung into action. Their practice on the Galapagos shark would pay off as they went to work on the hammerhead. But for future reference, the fishermen refused to reveal the techniques or the bait they used to turn this expedition into a rousing scientific success. 

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Learn More About Hammerhead Sharks >>

Comments

  1. Rebecca Gray
    Wichita, KS
    August 15, 2012, 7:27 pm

    Instead of bringing the hammerhead sharks on board for tagging, risking the sharks lives by suffocation as mentioned in the show, would it work better to use something like a dog-run in the water between two boats to keep it stable and use a pump outside the cage at the head end to cycle ocean water through the cage so the shark can breathe? The cage should be small enough to keep the shark from turning around, yet allow divers access from the top. Cage should be shallow enough to force shark near the top of the water for tagging. Bottom of cage should be drop-open hatch to release the shark when tagging completed. This procedure may be less stressful than removing the shark completely from the water. It may allow more time for further tests and measurements, which could ensure accuracy without so must haste. Just an idea. Not sure if it was considered as a possible method before filming.