Thursday, January 28, 2010

"Chatham, Carcarius has landed"

"Non invasive" archival pop up tagging with great whites has been a mainstay of research for the past decade.

CHATHAM — For years, information about the migration and feeding habits of great white sharks has been as elusive as the predators themselves. Now, thanks to information from a tag attached to a shark off Chatham last summer, researchers will soon have something to sink their teeth into.

At around midnight on Friday, Jan. 15, a data-logging tag popped loose from a shark 50 miles east of Jacksonville, Fla., and began transmitting data to researchers by satellite. The tag was one of several which were fastened to white sharks off Chatham last September, and is designed to detach and float to the surface after having collected information on water temperature, depth and light levels.

The tag transmitted information for about five days, and Senior Biologist Greg Skomal of the state's Division of Marine Fisheries is now poring over the data. Spokeswoman Catherine Williams said Monday that the process is slow.

“It was tracking since September, so there's a lot of data on the tag,” she said.

With help from fisherman Bill Chaprales, who wielded the harpoon, researchers tagged five white sharks in September after there were multiple shark sightings close to shore. The sharks prompted officials to close area beaches to swimmers, which in turn drew many curious sightseers to the shoreline.

“We're hopeful that we'll see all of the tags,” Williams said. “We're very interested to see what the data can tell us about this species.”

“For Massachusetts citizens and biologists and shark enthusiasts across the globe, this is an exciting opportunity to study these fascinating creatures,” state environmental affairs Secretary Ian Bowles said in a press statement. “We're looking forward to sharing the findings—so far, all we know is that this particular shark is a snowbird.”

Many species of fish, including sharks, migrate to New England's coastal and open waters in the summer months. At least a dozen shark species migrate in and out of New England waters annually. Massachusetts is the northernmost range for several species, and is an important area for monitoring the health and distribution of shark populations. Although relatively rare in New England, great white sharks are known to visit local waters, where they are sometimes seen feeding near seal colonies.

Last May, the journal Current Biology published Skomal's research on the migratory patterns of basking sharks. Using similar tagging technology, Skomal and his team documented the movements of the species, identifying previously unknown winter habitats. The discovery has implications for that species' conservation.

While many of the secrets of white sharks remain unknown, local officials would be content to have one question answered: will the sharks return this summer?

“That's difficult to predict,” Williams said. “We don't know if they'll be back.” But if the great whites return, and if it is possible to safely tag additional sharks, “we'll definitely take that opportunity,” she said.

Skomal's research is funded through the Division of Marine Fisheries' Recreational Marine Fisheries program. Among the funding sources for the work are grants from the Massachusetts Environmental Trust, the National Science Foundation and NASA.
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