Longest tiger shark tracking reveals bird-like migration

Brett Smith for redOrbit.com – Your Universe Online

Using the first-ever continuous, multiple year satellite tagging program, marine biologists have found that tiger sharks routinely perform a bird-like seasonal migration – from the tropical waters of the Caribbean all the way up to the more temperate waters of the mid-North Atlantic.

A new study on the research, published in the journal Scientific Reports, could have major implications for the conservation of tiger sharks.

“As apex predators, the presence of tiger sharks — and other large sharks — is vital to maintain the proper health and balance of our oceans,” Mahmood Shivji, a shark expert at Florida’s Nova Southeastern University and study author, said in a press release. “That’s why it’s so important to conserve them, and understanding their migratory behavior is essential to achieving this goal.”

Due to insufficient tagging technology and logistical concerns, researchers haven’t been able to effectively track tiger sharks for long periods in the past. The new research project saw researchers tracking the animals for three years or more in some cases. One particular shark, called Harry Lindo, was followed for more than 27,000 miles – which could be the longest distant a shark has ever been tracked, the researchers said.

The scientists were able to reveal that adult male tiger sharks in the Atlantic consistently spend their winters in Caribbean island locations. During the summers, the tiger sharks travel far into the North Atlantic, occasionally as far north as Connecticut. East Coast swimmers needn’t worry though, as the sharks stay well offshore.

“These repeated journeys were very unexpected,” said study author James Lea, a marine biologist from The Marine Biological Association in the United Kingdom. “The tiger shark has traditionally been considered a coastal species, and it is rare among sharks to so easily and habitually switch between the two vastly different environments.”

Sharks vacay in the same place each year

The researchers also noted that the sharks were remarkable adept at finding the same wintering area each year.

“Even though they’ve got a whole range of islands to choose from, it seems like each animal has its favorite winter spot,” Shivji said.

The research said they suspect the shark go down to the Caribbean to breed in the winter, then head out to sea in the summer in search of migrating loggerhead turtles, a favorite prey.

Study author Guy Harvey, a lead marine researcher at NSU, said the research project is particularly important because it could inform future conservation strategies.

“Protecting migratory species is a great challenge because they can be found in such a wide area,” he said. “Protecting the areas where animals, such as tiger sharks, spend the most time is a tractable goal once those areas have been identified.”

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