Ocracoke nature, flora & fauna

Ocracoke’s unexpected visitor

April 2013

 by Pat Garber

Ocracoke Island had an unexpected visi­tor on the afternoon of Monday, January 21. An­nounced by the pings from her tracking device, a North Atlantic Great White Shark swam along the island’s shore and briefly entered Ocracoke Inlet. The shark, sixteen feet long and report­edly weighing an amaz­ing 3,456 pounds, was one of 36 sharks—22 of them Great Whites–be­ing tracked by scientists from the research facility, Ocearch. The mature fe­male had been captured, tagged and released on September 17, 2012, off the coast of Cape Cod, and the researchers had followed her travels since then.

Mary Lee, named for the mother of one of Ocearch’s expedition leaders, Chris Fischer, had headed south from Cape Cod and had meandered her way down to Jackson­ville, Florida before turn­ing around and returning north. The tag, or beacon, which is attached to her dorsal fin, pings off of a satellite, giving exact de­tails of her location and allowing Ocearch to track her movements. Fischer   said that when one of the sharks swims too close to populated areas he gives notice so that people can stay safe. That is what he did when Mary Lee ap­proached Ocracoke on Jan­uary 21.

Ocearch, the organiza­tion conducting the re­search, is a non-profit dedicated to studying the giants of the ocean. Begun by Fischer, who hosted the Emmy Award-winning television series, “Offshore Adventures,” it provides support for leading re­searchers and research in­stitutions to conduct shark studies. Its 126-foot moth­ership, the M/V Ocearch, is equipped with a 75,000 hy­draulic lift, a research plat­form, and an at-sea lab.

Fischer and the crew at Ocearch are very excited about following Mary Lee, calling her “the most his­toric and legendary shark” ever tagged. They hope to learn more, from her and their other tagged sharks, about the medium and long range movement patterns of Great Whites. They are also interested in their re­productive behavior, the behavior of juveniles, in­dividual movements, the location of coastal aggrega­tion sites, and general life history. This knowledge will be useful in conservation efforts to protect sharks, which on a world-wide lev­el are in decline.

Sharks are among the most awe-inspiring, feared and misunderstood crea­tures on earth. They belong, along with rays and skates, to the class of fish, Chron­drichthyes, or “cartilage fish.” Their structure is sup­ported not by bone, but by cartilage, a flexible, elastic material full of cell spaces. They have tough, abrasive skin and are, contrary to common lore, are quite in­telligent. Of the more than 300 species, most are too small to pose a threat to hu­mans, and some are benign plankton-feeders. Great Whites are among the po­tentially dangerous species.

Great Whites, known to biologists as Carcharodon carcharias, are found in the coastal waters of all the great oceans. They belong to the Lamnidae family, also known as Mackerel Sharks, because of the shape of their tails. Portrayed in the book and movie, “Jaws,” as ferocious man-killers, they seldom attack humans, pre­ferring a diet of fish and marine mammals such as seals. They are not actually white, but may range from off-white to dark gray-brown, with white under­sides. They have a circula­tory modification known as a “rete mirabile” (wonder­ful net) that allows them to maintain a higher body temperature than the wa­ter around them. This gives them extra energy for high speed chases and attacks.

When Mary Lee ap­proached the Ocracoke coast Ocearch contacted the Hyde County Sheriff’s Dept., which called the Cape Hatteras NPS office at Ocracoke. Josh Vann, who took the call, immediately posted it on Facebook. He then drove the beaches to make sure there were no surfers in the water, and he warned several fishermen who were fishing in the surf.

Ocracoke is no stranger to visits from sharks. In July of 2011 a young girl was bitten by a shark while swimming off the island’s coast. She was air-lifted out and made a full recov­ery. Farther north, off Cape Hatteras in 2004, a man was attacked and killed by a shark. Spiny dog sharks are common inhabitants of the island’s waters in winter, often filling the fishing nets of commercial fishermen and providing a winter live­lihood. Long-liners catch Mako, Black-tip, Dusky, and Sandbar sharks in Oc­racoke’s offshore waters, and huge whale sharks and basking sharks occasion­ally wash up on the beach. In May of 1997 islanders streamed by the Fish House to see a ten-foot, six-inch Great White caught ac­cidentally by a long-liner fishing for smaller sharks.

Great Whites and other sharks, at the top of the ocean’s food chain, play a crucial role in maintaining a balance in marine ecosys­tems. Over-fishing threat­ens a number of species. With up to 25% of the great sharks facing extinction, re­search such as that being done with Mary Lee could play an important role in preserving them. As Mary Lee continues her jour­ney north, researchers and interested followers will continue to track her prog­ress. At last report she was headed for her home state of Massachusetts.

 

 

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