International study reveals sharks most affected by fishing are most needed to maintain healthy oceans. These big sharks help maintain balance through their eating habits and their sheer size is enough to scare away prey that could over-consume seagrass and other plant life needed for healthy oceans. Sharks can also help shape and maintain balance from the bottom-up. That means a variety of sharks in a variety of sizes are needed, yet their many and diverse contributions are under threat from overfishing, climate change, habitat loss, energy mining, shipping activities and more.
Journal/conference: Science
Link to research (DOI): 10.1126/science.adl2362
Organisation/s: Flinders University, The University of Sydney, Curtin University, University of Tasmania, James Cook University, Australian Institute of Marine Science (AIMS)
Funder: Shark Conservation Fund, a philanthropic
collaborative that pools expertise and resources to meet the
threats facing the world’s sharks and rays, funded the workshop
that launched this effort and cofunded S.D., J.H.M., and R.E.D.
through project 800011570 and Florida International University.
Shark Conservation Fund is a sponsored project of Rockefeller
Philanthropy Advisors. R.E.D. was funded by the Bertarelli
Foundation as part of the Bertarelli Programme in Marine
Science. E.M.D. was funded by an Earl S. Tupper Postdoctoral
Fellowship at the Smithsonian Tropical Research Institute.
Media release
From: Flinders University
Shark conservation must go beyond simply protecting their populations and prioritize protecting the ecological roles of sharks, according to new research.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.These big sharks help maintain balance through their eating habits and their sheer size is enough to scare away prey that could over-consume seagrass and other plant life needed for healthy oceans.Sharks can also help shape and maintain balance from the bottom-up. That means a variety of sharks in a variety of sizes are needed, yet their many and diverse contributions are under threat from overfishing, climate change, habitat loss, energy mining, shipping activities and more.The study, led by Florida International University (FIU) and supported by Flinders University was published today in Science and sheds new light on what role sharks play in healthy oceans and why size should be a factor in conservation decisions.“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, researcher at Florida International University and lead author of the study.The issue of shark conservation becomes all the more critical as global temperatures increase, leading some sharks to head into new areas where they can find the temperatures, they can thrive in.Besides helping to maintain balance within the food web, reef sharks feed in offshore waters and bring nutrients back to the reef. Others move nutrients around that are used at the base of the food chain.Sharks can also serve as food for other species and even as scratching posts for fish to remove parasites. The problem is 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. As their numbers plummet, their important roles in ocean health are also lost.A co-author on the study at Flinders University, Professor Charlie Huveneers says human activities, like tourism, and growth in coastal development or energy infrastructure can affect shark behaviour and feeding patterns, and therefore, their ecological role.“Regulations and monitoring are required to ensure that we can continue to build on a strong blue economy while avoiding detrimental impacts on our marine ecosystems.”“National and international policy must focus on actions that rebuild populations and restore sharks’ functional roles,” said Mike Heithaus, study co-author and FIU marine ecologist.“That requires action to increase both spatial measures like Marine Protected Areas and fisheries management measures like catch/size limits and gear limitations. If people want healthy oceans, we need healthy shark populations.”“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.”