Friday, June 20, 2014

Great White Shark Population Growing Off U.S. East Coast

Great White Shark. Credit: Greg Skomal / Mass. Division of Marine Fisheries

The great white shark population is making a comeback along the U.S. and Canadian East Coast, a recent study by NOAA Fisheries finds.

The study, which NOAA touts as the most comprehensive ever on seasonal distribution patterns and historic trends in abundance of great white sharks (Carcharodon carcharias) in the western North Atlantic Ocean, used records compiled over more than 200 years to update knowledge and fill in gaps in information about this species.

In the 1970s and 1980s, relative abundance data indicated that white shark populations declined, likely due to expanding commercial and recreational shark fisheries. However, from the early 1990s onward, abundance has increased.

“Both the declines and, more notably, the increases in abundance seen in our study were supported by multiple data sources” said Cami McCandless, a biologist in the NEFSC’s Apex Predators Program and a study co-author. “The increase in relative abundance is likely due, in part, to the implementation of management measures. The U.S. has managed its shark fisheries since 1993, and banned both commercial and recreational harvesting of white sharks in 1997.”

Great White Sharks Migrate To Florida For Winter

The study also found that great white sharks occur primarily between Massachusetts and New Jersey during the summer, off Florida during winter, and with a broad distribution along the U.S. East Coast during spring and fall. 

During winter, most white sharks are found off the northeast coast of Florida, the Florida Keys, and in the Gulf of Mexico offshore of Tampa Bay, Florida, where they have generally been considered rare. 

In spring, the distribution expands northward, and by summer most sharks occur in the waters off New York and southern New England, and around Cape Cod. In August, some large juvenile and mature individuals reach Newfoundland and the Gulf of St. Lawrence, the northernmost limit of their range. During fall, most sharks remain in northern latitudes, but begin to shift southward in November and December.  

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