Big sharks equal big impact, but there's a big problem

FIU-led study reveals those most affected by fishing are most needed for healthy oceans

MIAMI, Aug. 1, 2024 /PRNewswire/ -- Shark conservation must go beyond simply protecting sharks — it must prioritize protecting the ecological roles of sharks, according to new research published today in Science.

The largest sharks of many of the biggest species, such as tiger sharks and great whites, play an oversized role in healthy oceans, but they are often the most affected by fishing. They help maintain balance through their eating habits. Sometimes their size is enough to scare away prey that would over-consume much-needed plant life. Sharks also help from the bottom-up. A variety of sharks are needed for healthy oceans, yet they are under threat from overfishing, climate change, energy mining, shipping and more. The study, led by Florida International University (FIU), sheds light on what role sharks play in ocean health and why size should be a factor in conservation decisions.

"Some of these roles are really important," said Mike Heithaus, study co-author and executive dean of FIU's College of Arts, Sciences & Education. "We need to maintain a diversity of sharks in our oceans as well as a wide range of sizes of sharks. We need to rebuild heavily depleted populations and manage for how sharks will function amid climate change."

Heithaus' work in Shark Bay, Australia is the most detailed study in the world on the ecological roles of sharks. There, he documented the top-down roles like keeping prey in check.

"It's time to have a conversation about everything sharks are doing to maintain ocean health so we can better prioritize conservation efforts and have the biggest impact," said Simon Dedman, FIU marine scientist and co-lead author.

Sharks feed in offshore waters and bring nutrients back to the reef. Others move nutrients that are used at the base of the food chain. Sharks also serve as food themselves and even as scratching posts for fish to remove parasites. But shark abundance has plummeted by 71 percent for oceanic species in the past 50 years. Populations of the top five reef shark species have been depleted by 63 percent.

"This study verifies what we've long suspected – sharks are critical to ocean health," said Lee Crockett, executive director of the Shark Conservation Fund which funded the study. "This landmark study serves as confirmation that marine conservationists, philanthropists, policymakers, and the public alike need to recognize that sharks are keystone species that have a now-proven significant effect on marine environments."

Shark conservation becomes all the more critical as global temperatures increase, leading some sharks to move away from the warming waters. As the blue economy expands, people's encounters with sharks will likely increase. Finding a balance that protects the sharks most needed for healthy oceans is hitting a critical point. The scientists recommend policy to increase spatial measures like Marine Protected Areas and fisheries management measures like catch/size limits and gear limitations.

Media Contact:
JoAnn Adkins
305-348-0398
[email protected]

SOURCE Florida International University