If scientists have been tagging sharks for decades, why are we still in the dark about what so many shark species do? Especially since this is crucial information for protecting threatened populations? First, I learned, you have to check the tag.
"Shark tagging has evolved over the years from small conventional tags on sharks to acoustic tags and satellite-based technology," explains Greg Skomal, a marine biologist with Massachusetts Marine Fisheries. He estimates that since the 1960s around 200,000 sharks have been tagged conventionally, allowing scientists to get basic data on population sizes, mortality rates, and some movement patterns when the sharks are recaptured. But holes remain. "If we don't know how they live, we can can't save them," Skomal says.
This spring Emily Sohn reported on Discovery News that Skomal and his colleagues used satellite tagging to discover that basking sharks, which are threatened, migrated from the East Coast all the way to South America in the winter. Since then, data showed the sharks returning to New England during warmer weather. Skomal tells me that even though satellite tagging technology has existed for around 10 years and is on hundreds of sharks, he envisions the tags themselves getting smaller and more refined. The smaller the technology, the more sensors can go into the tags, including ones that could detect changes in the shark and in the environment around it.
On Twitter I've been promoting #sharkhug as a hashtag during Shark Week. I had no idea that scientists were actually doing this to make the tagging process less stressful for sharks. The process is called "tonic immobility" and involves massaging a point near the nose (video). "[W]ho would have ever thought you could grab a shark, hug it, put it to sleep, and then tag it," marine biologist Andy Dehart recently told CBS News correspondent Daniel Sieberg. Non-scientists should keep shark hugs virtual for now, though.
Photo: A basking shark with a satellite tag. Credit: Greg Skomal.
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Tags: Conservation, Green Tech, Satellites, Water
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