blacktip sharks
Adults average about 5ft long but blacktip sharks as large as 8ft have also been reportedGetty

Thousands of blacktip sharks have been spotted off the Florida coast as part of their northern migration. Arial footage from above the water showed thousands of little black dots around the sea: "All the dots, every single one of those is a shark," said professor of biological sciences at Florida Atlantic University Dr Stephen Kajiura.

Speaking to WPBF 25, Kajiura said: "This year, the sharks are coming in a little late. Typically, they get here around January or so, but this year they aren't arriving until the end of January." He also said the last time he flew over the seas he spotted at least 10,000 of the sharks. Researchers at the university are now trying to work out why the sharks are migrating later than usual and what has attracted so many to the Florida coast now.

Kajiura suggested that the change in migration pattern might be because of climate change: "This indicates northern migration is actually expanding. They're moving farther and farther north, and it may be in response to global climate change. The water is getting warmer."

WPBF 25 also asked Kajiura whether Florida beach-goers need be worried about the mass of sharks just offshore – "The general answer is no. For the most part, these sharks are really skittish, so when you get in the water, they're going to scatter and go away."

Blacktip sharks have black markings on most of their fins; they're incredibly fast and can be found all over the world. The ones found off the east coast of the USA tend to migrate north to the North Carolina coast in the summer and spend winter south by Florida. Adults average about 5ft long but blacktip sharks as large as 8ft have also been reported.