Scientists follow sharks’ migration patterns to brighten preadators’ public image
She prefers to summer in the glistening waters off Cape Cod. But come December, Katharine the great white shark travels more than a thousand miles to another tourist destination: Daytona Beach.
The 14-foot, 2-ton female is one of dozens of large marine predators scientists are now tracking — using satellite tags affixed to their dorsal fins — to peer into secret lives of sharks and their dramatic journeys north and south along the East Coast.
Researchers are hoping the shark-migration data will enlighten local governments on the coast and people venturing into Atlantic waters enough to lead to better management of human-shark relations that, in the past, have been deadly for both species.
“Sharks are the equivalent of Yankee snowbirds,” said University of Florida shark expert George Burgess, keeper of the International Shark Attack File. “With shark attacks, you’ve got two groups that need to come together, but for those two groups to do so, you got to look at the behavioral issues of both.”
In recent years, scientists and conservationists have discovered that the southward pilgrimage of the ocean’s toothy beasts is related in some measure to changing water temperatures.
Palm Beach Atlantic University’s Stephen Kajiura and his team took aerial photos along the coast during peak season — January through March — that revealed hundreds of blacktip and spinner sharks congregating close to shore.
“You can get well over 800 sharks per square kilometer (about a square half-mile),” he said. “But once the water gets above 24 degrees Celsius (75 degrees Fahrenheit), we are not seeing the sharks.”
With time, the sharks swim north, but some stop along the way.
Volusia and Brevard counties are the shark-bite centers of the state for a reason. They have a large population of sharks that reside in the inlets, sandbars and surf zones of east Central Florida year-round.
The same New Smyrna Beach breakers that attract surfers are home to an “aquatic smorgasbord.”
“It’s a good place to be predator,” Burgess said.
As the two species collide, unfortunate things happen.
“Because of the limited visibility, breaking surf and aggressive currents, these (sharks) have to make a quick decision to get their next meal.”
Sometimes the flash in the water is not a fish but a bright palm or sole of the foot. In 2013, there were 23 confirmed unprovoked shark attacks in Florida, and eight occurred in Volusia — a decline from 2012.
The state led the nation and world in attacks — as it does nearly every year — because its citizens and visitors spend so much time in the water along hundreds of miles of coastline, scientists say.
Surfers, body boarders and kiteboarders are often the victims of bites.
None was fatal, and few ever are. Florida averages one death a decade, and statistically, beachgoers are more likely to be killed while driving to the coast than in an encounter with a shark, researchers said.
But when it does happen, it’s big news. From 2001 to 2013, there were 478 reported shark attacks and 12 fatalities nationally. Florida comprised 295 of those attacks and three deaths.
The most recent victim was kiteboarder Stephen Schafer, who died in February 2010 after he was bitten in the thigh by what biologists think was a bull shark in Stuart, according to news reports.
Globally, the number of shark attacks has grown each decade since 1900 as people spend more recreational and commercial time in the sea, Burgess said.
Meanwhile, shark populations are dwindling: “The real story is not the shark attacks but the sharks themselves,” he said.
HOW TO AVOID SHARK ATTACKS
• Avoid nighttime swims when sharks are most active.
• Avoid wearing shiny jewelry, brightly colored or patterned clothing.
• Don’t swim if you’re bleeding. Sharks can smell blood from far away.
• Stay clear of baitfish. A predator is never too far from its prey.
• Stay calm if you do see a shark, and maintain your position as quietly as possible. Most sharks merely are curious and will leave on their own.
Source: International Shark Attack File