Does Human Interaction Affect Shark Behavior?

Researchers from the University of California (Santa Barbara) Marine Science Institute wanted to find out, so they went to Palmyra, a remote atoll in the central Pacific Ocean, where shark populations are healthy, fishing is not allowed, and its near pristine underwater world is rarely dived. It is home to a small scientific research station, where researchers dive in a handful of locations. This makes the atoll an ideal site for studying whether and how shark abundance and behavior differs between locations where diving is more common and those where it is not.

The team studied whether scuba-diving activities have long-term consequences for shark populations. They used baited remote underwater video systems -- cameras lowered to the ocean floor with a small amount of bait -- to survey sharks and other predators from the surrounding reef.

"After reviewing 80 hours of underwater footage taken from video surveys conducted in 2015, 14 years after Palmyra was established as a wildlife refuge and scientific diving activities began, we found that shark abundance and shark behavior were the same at sites with and without a long history of scuba diving," said co-author Jennifer Caselle, a research biologist.

"Unfortunately, human impacts on shark populations are ubiquitous on our planet," said lead author Darcy Bradley, a postdoctoral researcher at UCSB's Bren School of Environmental Science & Management. "That makes it difficult to separate shark behavioral changes due to scuba diving from behavioral changes caused by other human activities like fishing."

"Our results suggest that humans can interact with reef sharks without long-term behavioral impacts. That's good news. It means that well-regulated shark-diving tourism doesn't necessarily undermine shark conservation goals."

(Source: Marine Ecology Progress Series 2017)