Researchers at Florida Atlantic University captured the annual Blacktip Shark migration off Singer Island over the weekend.
The footage, which you can see here, shows thousands of sharks heading south toward warmer water. These sharks are often called the "snowbirds of the sea," because they migrate south during the cold months when water temperatures drop below 71 degrees. When the weather and water warm back up they will return north.
The video was taken right off of John D. MacArthur Beach State Park in North Palm. Blacktips are regarded as fairly timid animals and account for very few attacks on humans. In places like Georgia, South Carolina, and northern-central Florida, there are areas that have cloudy inlets and an abundant supply of baitfish. Those are the areas where there are more incidental bites on people. In the much clearer waters off South Florida, sharks rarely mistake humans for prey, according to Stephen Kajiura, a professor in the Department of Biological Sciences and director of the Elasmobranch Research Laboratory in FAU’s Charles E. Schmidt College of Science.
Kajiura and other researchers say this year's migration video shows significantly fewer Blacktips than in previous migration seasons. “In fact, it was so low that we estimated the population to be about one-third of what we have seen in previous years,” he said, adding that tracking the shark migration isn't just about public safety, but also an important indicator of ocean health.
During the migration, the Blacktips sweep through coastal waters and sort of “spring clean," weeding out weak and sick fish, which helps preserve coral reefs and seagrass. "[The sharks] are just simply stopping when they reach their optimum water temperature," Kajiura said. "That might have ramifications throughout the ecosystem... you might have an abundance of sick or diseased fish here that are not being cleaned out."
That can create detrimental effects that trickle down the food chain to coral reefs and throughout our ecosystem. Kajiura doesn't attribute the warmer coastal waters in recent years entirely to global warming, but he does think it may provide a glimpse of what's to come for shark migrations in a warmer world. “We want to make sure that these snowbirds come back to South Florida, because if they don’t, it will have a huge ecological impact in this region.”
For more information about Blacktip sharks and migration patterns from FAU, click here.