Massachusetts Division of Marine Fisheries tracks two white sharks from Bay State to north coast of Florida
Electronic tagging reveals deep dive to 1,500 feet and seasonal residency in southern New England
Click here for the audio of the news conference. file size 23MB
Click here for photographs of the white shark tagging in September.
BOSTON - March 3, 2010 - State marine biologists have tracked three electronic tags placed on white sharks in waters off Cape Cod last September to the coast of North Florida, providing clues to the migration path to wintering grounds and other habits of these top marine predators, Energy and Environmental Affairs (EEA) Secretary Ian Bowles said today.
The first tag - which was placed on a 12-foot long shark - surfaced on January 15, 50 miles east of Jacksonville, Florida and began transmitting data. Two weeks later, the second tag - which was placed on a 10-foot long shark - surfaced on February 4, 30 miles north of where the first tag appeared. A third tag appeared off the coast of Florida, 80 miles south of the first two tags, on Monday, March 1.
Under a project led by Division of Marine Fisheries (DMF) Senior Biologist Greg Skomal, electronic tags were placed on five great white sharks in waters off of Chatham in September. The first two tags that surfaced this winter were placed on the sharks on September 5. The tags, which collect and record water temperature, depth and light levels to help scientists determine where a shark travels, transmit data for several days using satellite-based technology. Using light-level data archived by the tags, biologists were able to recreate the most probable movements of the sharks.
"This research reveals new insights into shark behavior - deep-diving to 1,500 feet and following a migratory track along the Eastern Seaboard - and informs biologists about the habits and preferences of this amazing species," said Secretary Bowles, whose office includes DMF, a division of the Department of Fish and Game (DFG). "These three sharks have turned out to be snow birds, and I'm hoping that the tags still on other sharks will tell us more about the travels of these great creatures."
Over the past several weeks, Skomal - who heads DMF's shark research program - has analyzed data transmitted by the tag looking for information about how deep and how far the sharks traveled, information that allows scientists to better understand white sharks' migratory behavior. Additional tags may surface and transmit data this spring.
The preliminary data indicate the sharks remained in southern New England waters until September before moving west and south along the East Coast of the U.S. While off the coast of Massachusetts, the sharks demonstrated daily movement from the surface to depths below 100 feet.
During their southern migration, the white sharks remained on the continental shelf and continued to traverse the water column, an area that stretches from the surface to the bottom, on an almost daily basis. By mid- to late October, they were off the coast of North Carolina. The first tags to surface indicate that two of the sharks arrived off the coast of northern Florida by early December, and remained in this region until their tags jettisoned.
Although the sharks moved between the surface and the bottom, the sharks spent more than 90 percent of their time at depths less than 150 feet. The white sharks moved through water that ranged from 7 degrees to 27 degrees Celsius (45-81°F), but spent more than 80 percent of their time in waters with moderate temperatures, ranging from 15 degrees to 23 degrees Celsius (59-73°F).
One of the sharks exhibited a deviation from this pattern when it entered the Gulf Stream off North Carolina for 10 days in early November and exhibited daily dives to depths as great as 1,500 feet. During this time, the shark moved off the continental shelf and through water that was 7.4 degrees to 27.6 degrees Celsius as it dove to these great depths.
"By revealing new discoveries about shark behavior, Dr. Skomal and his team continue to do the important work of studying the migratory paths and behavior of marine species in Massachusetts coastal waters," said DFG Commissioner Mary Griffin. "We hope it will inspire young biologists to become passionate about science, following in Dr. Skomal's footsteps."
"This research will help inform biologists about the habits and preferences of white sharks and complements our existing marine research aimed at protecting and understanding local marine species," said DMF's Director Paul Diodati.
Having analyzed the tag data, Skomal and his team are now engaged in the more difficult task of interpreting the findings. The analysis of the first two tags show the sharks demonstrated seasonal residency off southern New England and northern Florida, two highly productive areas that likely provide ample feeding opportunities. The purpose of the deep diving behavior exhibited by one of the sharks remains a mystery, but such behavior is typical of white sharks off the Pacific Coast. With two additional tags scheduled to pop up in the coming months, the scientists are hopeful that more insights into the life history and ecology of these sharks and their movements in the North Atlantic are forthcoming.
"The most surprising thing for me is to find out that these sharks are closely associated with the Continental Shelf and that association may tell us more about their mating and feeding habits," said Dr. Skomal. "While this is a small sample of data, the information provides some first insights and glimpses into where these sharks are traveling to and may point to a well defined migration route."
After multiple shark sightings off the coast of Chatham last summer, Skomal and other state biologists set out to identify the species of the sharks off Monomoy Island in Chatham. Skomal, along with harpooner Bill Chaprales, captain of the fishing vessel Ezyduzit, placed the electronic tags on the sharks with the help of spotter pilot George Breen and Nick Chaprales, the boat's driver. This was the first successful tagging of white sharks in the Atlantic Ocean using electronic satellite technology.
In 2004, the DMF attempted to electronically tag a great white shark that was stuck in a shallow embankment at Naushon Island off of Cape Cod. While DMF's Skomal was able to place a tag on that shark, the device detached from the animal shortly afterward without acquiring any data.
Many species of fish, including sharks, migrate to New England's coastal and open ocean 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 of sharks 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, peer-reviewed journal Current Biology published Skomal's research on the migratory patterns of basking sharks. Using similar tagging technology, Skomal and his team documented the migratory habits of these large sharks, identifying previously unknown winter habitat - a discovery that has implications for the species' conservation. Click here to find out more about DMF's basking shark research.
DMF's shark research program is one of eight marine fisheries research programs funded through DMF's Recreational Marine Fisheries program. The shark research program is beneficiary of several federal grants.
The Department of Fish and Game (DFG) is responsible for promoting the enjoyment and conservation of the Commonwealth's natural resources. DFG carries out this mission through land preservation and wildlife habitat management, management of inland and marine fish and game species, and enforcement of the Massachusetts Endangered Species Act. DFG promotes enjoyment of the Massachusetts environment through outdoor skills workshops, fishing festivals and other educational programs, and by enhancing access to the Commonwealth's lakes and ponds.