Overfishing

There are more than 500 species of sharks in the world’s oceans, from the 7-inch dwarf lantern shark to whale sharks that can grow to over 35 feet long. They’re found from polar waters to the equator, at the water’s surface and miles deep, in the open ocean, along coasts and even in some coastal rivers. With such diversity, it’s no surprise that sharks serve many ecological functions. For example, the largest individuals of some big predatory species, such as tiger and white sharks, can have an oversized role in maintaining balances among species. They do this by feeding on prey and sometimes by just being present and scary enough that prey species change their habits and locations. In a newly published study, colleagues and I surveyed decades of research on sharks’ ecological roles and considered their future in oceans dominated by people. We found that because sharks play such diverse and sometimes important functions in maintaining healthy ocean...

Fishermen across the Gulf of Mexico are reporting that something is eating fish off their lines. What’s to blame? Many recreational anglers point a finger at sharks. This conflict has caught politicians’ attention. Congress has directed the National Oceanic and Atmospheric Administration, which regulates fishing in U.S. waters, to review shark and dolphin interactions with fisheries, and the U.S. House of Representatives recently passed the SHARKED Act, which would create a task force to address the problem. I’ve studied this conflict, which is formally called depredation, for the past decade. While some shark populations in the Gulf of Mexico, such as bull sharks, are increasing, my colleagues and I have found evidence that human perceptions are also an important factor. A Gulf angler races to land a fish before sharks take it. Sharky waters The Gulf of Mexico is home to more than 70 species of sharks – and those...

My colleagues and I mapped activity in the northeast Pacific of “dark” fishing vessels – boats that turn off their location devices or lose signal for technical reasons. In our new study, we found that highly mobile marine predators, such as sea lions, sharks and leatherback sea turtles, are significantly more threatened than previously thought because of large numbers of dark fishing vessels operating where these species live. While we couldn’t directly watch the activities of each of these dark vessels, new technological advances, including satellite data and machine learning, make it possible to estimate where they go when they are not broadcasting their locations. Examining five years of data from fishing vessel location devices and the habitats of 14 large marine species, including seabirds, sharks, turtles, sea lions and tunas, we found that our estimates of risk to these animals increased by nearly 25% when we accounted for the presence of dark v...

All of the saltwater bodies on Earth make up one big ocean. But within it, there is infinite variety – just ask any scuba diver. Some spots have more coral, more sea turtles, more fish, more life. “I’ve been diving in many places around the world, and there are few locations like the Fuvahmulah Atoll in the Maldives,” Amanda Batlle-Morera, a research assistant with the Important Shark and Ray Areas project, told me. “You can observe tiger sharks, thresher sharks, scalloped hammerheads, oceanic manta rays and more, without throwing out bait to attract them.” Identifying areas like Fuvahmulah that are especially important to certain species is a long-standing strategy for protecting threatened land animals, birds and marine mammals, such as whales and dolphins. Now our team of marine conservation scientists at the Important Shark and Ray Areas project is using it to help protect sharks and their relatives. I am a marine conservation biologis...

“Shark!” When you hear this word, especially at the beach, it can conjure up images of bloodthirsty monsters. This summer, my colleagues and I are eager to help the public learn more about these misunderstood, ecologically important and highly threatened animals and their close relatives – rays and chimaeras. As a marine biologist focused on conserving sharks, I want people to know that an estimated one-third of them are at risk of extinction. Second, there’s an amazing variety of species in an astounding variety of shapes sizes and colors, and many of them get very little attention. Here is an introduction to a group of fishes that are at extremely high risk of extinction, and also delightfully weird: the rhino rays, named for their elongated noses. Scientists tag endangered sawfish off Florida’s west coast to identify and protect their habitats and educate the public about them. Motley shapes Rhino rays a...