'There is shift in behavior': Sharks in the Gulf of Mexico learn boats mean food

Sharks are feasting on fish caught by humans in the Gulf of Mexico after learning to associate boats with food, shark scientists say. 

Instances of shark depredation in the region have increased significantly in the past decade, Marcus Drymon, a shark scientist at Mississippi State University, told Live Science in an email. 

"Although difficult to demonstrate empirically, it does appear that there is [a] shift in behavior (i.e., a learned response)," he said. 

In the new National Geographic "Sharkfest" special "Shark Beach with Anthony Mackie," researchers along the Gulf Coast investigate the impact of this growing conflict between fishers and sharks. "We're fishing in the same spot that the sharks are fishing in," Jasmin Graham, a marine biologist who founded Minorities in Shark Sciences, said in a clip from the documentary. #

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"Sharks learn really, really quickly. They learn engine means food," she said. "So they start coming straight for the boats. Now we're in direct comPetition with them for the same fish, and that's when you get depredation."

Shark depredation affects fisheries worldwide, but it is particularly prevalent in the U.S. and Australia, where sharks and humans often overlap, leading to conflict. The problem is complicated. In the 20th century, humans decimated shark populations, and humans still kill an estimated 80 million sharks per year as a result of demand for their fins and through bycatch.