The ocean phenomenon that brings sharks closer to shore ::

Several reports of shark bite injuries and a series of sightings of marine predators off the northeastern coast of the United States baffled summer swimmers.

But in New York Long Island and Cape Cod, the Massachusetts peninsula, where many of the recent suspected shark encounters have occurred, are they experiencing anything exceptional? Yes and no, according to Gavin Naylor, director of the Florida Program for Shark Research at the University of Florida at Gainesville.

Globally, shark attacks are at similar levels to previous years, said Naylor, who is also curator of the Florida Museum of Natural History, but there are signs that the northeastern coast of the United States could see a increase.

“We’re trending for this time of year. I think globally, we usually get between 70 and 80 unprovoked shark bites around the world. But that’s a global phenomenon. And it’s unevenly distributed.” , explained Naylor.

“One year we could have two or three bites in Hawaii in quick succession. Next year it could be New Caledonia; it could be in Western Australia. And this year it’s off Long Island.”

Naylor has refused to provide the totals since the beginning of the year so far, saying it takes time to investigate and authenticate the reported bites. (Naylor’s work at the Florida Museum of Natural History involves monitoring data on shark attacks.) Last year, there were 73 confirmed unprovoked cases of shark bites, in line with an average of 72 incidents throughout the year. year in five years. However, there have been 11 shark-related deaths, compared to an average of five per year.

Pisces, not humans

The sharks the swimmers encountered off Long Island were looking for food, not targeting humans, Naylor said. Most have been identified as sand tiger sharks, Naylor said, which, while scary-looking, aren’t considered aggressive. They probably ventured into coastal waters to prey on abundant schools of bait fish near the shore.

The shoals have been particularly dense this year due to warm ocean currents breaking away from the Gulf Stream into the Atlantic Ocean and extending along the northeastern coast, he explained. These waters are richer in chlorophyll, allowing plankton to bloom, which also attracts bait fish.

“These bait fish are found in schools of hundreds of thousands – or millions,” Naylor said, “and when they get close enough to shore, the sharks follow them.

“The sharks are swimming around trying to chase their dinner. People are splashing around with the beach balls in their circle. … The surf zone gets pretty dark due to all the energy and the sharks are all agitated because they are excited to see all this food: every now and then they make a mistake “.

Contributing to the problem is a sand tiger shark hatchery, discovered in 2016, off the coast near the coastal waters of Long Island’s Great South Bay, where sharks between the ages of several months and 5 years feed and grow. . (Sharks are born off the southeastern coast of the United States before migrating north and spending the summer in New York waters and returning south again in the fall, according to the Wildlife Conservation Society.)

Unlike adult sand tiger sharks, which are up to 9 feet (2.7 meters) long, juveniles 4 to 5 feet (1.2 to 1.5 meters in length) can approach the shore to chase down the fish.

“As you can imagine, (the same) with any mammal, juveniles don’t have the same experience. They don’t have the same pattern recognition skills as adults,” Naylor said. “We strongly suspect it is the young and their judgment and discernment between what someone’s foot is and what is a flash of bony fish scales.

“You have a bunch of teenage sharks and they’re running around hunting for fish.”

Great whites

Different dynamics were at play off Cape Cod, where several great white sharks were spotted this summer, resulting in the closure of at least one beach. Naylor said there are no reports of shark bites known to him.

During the summer and fall, white sharks hunt seals – their favorite prey – along the region’s shoreline, which can bring them closer to popular beaches. Based on tagging data from 14 sharks, a study published last year in the journal Wildlife Research found that they spent nearly half of their time at depths of 15 feet (4.6 meters) or less. This means that there is a high potential for their presence in recreational waters frequented by swimmers and surfers.

“Until now, we didn’t know how much time they spent in shallow water near the coast,” lead author Megan Winton, a researcher at the Atlantic White Shark Conservancy, said in a news release last year. The North Chatham, Massachusetts nonprofit provides scientific research funding and resources to improve public safety.

The great white shark population off Cape Cod has increased along with the local seal population, which has rebounded in the decades since the 1972 Marine Animals Protection Act.

It is the only place in the Atlantic Ocean where great white sharks congregate. To date, around 300 great white sharks have been identified and tagged by researchers, but there is still no official population estimate.

Since 2012, there have been four unprovoked attacks by white sharks against humans along the Cape Cod coast, including one fatal attack in 2018, the first in Massachusetts since 1936.

Regardless of the type of shark, Naylor said the measures to protect yourself are similar – don’t swim or surf alone and don’t swim near large schools of fish or if you see seals nearby. Don’t wear jewelry in the water that a shark might mistake for the glitter of fish scales. If you see a shark, come back out of the water slowly. Don’t panic and wallow.


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