December on Cape Cod, Massachusetts is quiet. And the locals love it. They have their roads and coffee shops back to normal pace. Everyone seems to take a deep breath and sigh. And even the threat of upcoming Nor'Easters isn't on the minds of the locals, just yet.
47 degrees Fahrenheit. That's when shark biologist Greg Skomal, of the Massachusetts Division of Marine Fisheries says Great White Sharks are on the edge of the temperature they tolerate. Right now, mid December, sharks are on the move south. Of the 150 tagged sharks by Greg Skomal and his research team, most have left the area. Temperature is the motivating factor. So like the tourists, the White Sharks are heading out and leaving the locals to breathe a sigh of relief.
An important research organization which is also conducting critical research around the globe, is OCEARCH. OCEARCH conducts research aboard the M/V OCEARCH which contains a 75,000 lb capacity hydraulic platform that is designed to lift marine animals safely out of the ocean for access by a multidiscipline research team. By carefully securing the shark on the vessel while hoses are set to produce a continuous flow of seawater over the gills, an impressive 12 samples are able to be completed in 15 minutes.
Luna, a 15 ft female weighing 2137 lbs was originally tagged by OCEARCH off the coast of Nova Scotia on October 8. This impressive female was worked up by the research team made up of marine biologists and veterinarians. Through her tagging devices, we know that Luna is, as of December 7, traveling south along the continental shelf, roughly 50 miles west of Long Island. 103 days since being tagged, Luna has traveled over 1675 miles. In the month of October she clearly enjoyed feeding in the Bay of Fundy, before her journey to warmer waters began. Now she is on a clear path south. It is important to follow adult White Sharks, to understand where they are going and potentially where they go to breed.
With this satellite mapping, it would appear that the reason for these migration routes would have to do with the these drops in temperature. However, in recent years, Dr. Skomal has noticed that some sharks will tend to stick around a bit longer--as late as the end of December--before migrating South.
Climate-change has been affecting the rising of water temperatures. This could be what determines how long the sharks stay. However, Great Whites are endothermic. This means that they can regulate their body temperatures instead of having to move to warmer or colder waters.
So now the question is, would these sharks stay around longer even if the oceans were not warming? Because much is unknown about mating grounds, researchers believe they move south with their mating season. The colder the water gets, the more energy these sharks have to exert in order to acclimate to these cold temperatures. So migrating south actually helps them conserve energy.
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