Why Fewer Blacktip Sharks Are Migrating to Florida
March 8, 2018—In the largest ocean migration on U.S. coasts, blacktip sharks make seasonal trips between Florida and North Carolina. For 15 years, marine biologist Stephen Kajiura of Florida Atlantic University has watched the blacktips’ journeys, monitoring population and locations through aerial photography and tracking tags. Kajiura's team has seen impressive numbers, including a single group of 15,000 sharks. But the migration count has dropped to a third of the norm. A stretch of the Atlantic from North Carolina to Maine has spiked in temperature, rising faster than 99 percent of ocean regions. Fish are sensitive to water temperature. An average rise of 3.6 degrees Fahrenheit is enough to keep many blacktips in the northern waters. A sudden absence of a predator in Florida, and a sudden presence up the coast, can harm both ecosystems. Kajiura's goal is to restore the migrations.
