Why the Ecologically Important Basking Shark Is in Trouble

The Great White Shark is famous for the movie Jaws. The movie Sharknado featured Great Whites and Hammerheads. These fan favorites can steal the spotlight in conservation efforts, causing lesser-known but equally vital species to be overlooked. One species in particular, the Basking Shark or Cetorhinus Maximus, is the second-largest shark species in the world. This creature has been recorded to grow over 40 feet long. Given their massive size, it is no surprise that shark expert and Executive Director of the Pelagic Shark Research Foundation (PSRF), Sean R. Van Sommerman, began to notice their decline.

Silent Strainers of the Sea

Note: Before we get started, let’s define what pelagic actually means. “Right now, the word pelagic can be a little obscure”, he explains. “But it refers to the open ocean, so the offshore, high seas environment”. Often called the pelagic zone, this area is the largest habitat on Earth, covering a large portion of the Earth’s surface. And it is here, where the basking sharks call home.

This pelagic dweller likes to cruise near the surface level of the ocean with its mouth agape to feed on plankton and other nutrients in the water. Although their diet mainly consists of plankton, they also eat other small organisms like crustaceans. To give you an idea of what this slow-moving shark looks like in water, click this link here. This behavior gives them the appearance of basking in the ocean, which is how they got their name. This method of feeding, known as filter-feeding, is uncommon in sharks. Basking sharks are one of just three shark species known to filter feed. And unlike other filter-feeding sharks, these feed by passively moving through the water. This means they must keep moving to feed, allowing water to pass through their pharynx, which filters out plankton.

As a massive filter feeder, this species is vital to regulating food webs by keeping plankton species in check. Filter feeders help maintain ocean health by cycling nutrients and improving overall water quality. Without species like these, plankton populations could grow unchecked, potentially damaging aquatic ecosystems and, in turn, affecting humans.

Out of Sight, Out of Sea

This massive migrator does not have many natural predators, but it often falls victim to human activities. Human activities are a major driver of wildlife declines. Van Sommerman notes, “In my lifetime, I have seen the abundance of certain marine species decline, the decimation of rivers, and even fisheries are not what they used to be.”

Many factors have impacted these giants, including overexploitation, entanglement in fishing gear, collisions with boats (due to their slow movement), microplastics, and, of course, climate change. Just like many other species, these threats have contributed to their decline.

For starters, their large size makes them targets for collection and hunting, particularly for their fins. While hunting of these creatures has existed for a long time, many believe that Jaws caused a resurgence of shark hunting. Typically, people hunt sharks for their oil, fins, and liver. A basking shark’s liver makes up about 25 percent of its body weight, which adds to its popularity among hunters. In some countries, the demand for shark fins fuels the hunt. Prices of fresh fins can fetch prices upwards of $1,000 in certain markets. Their enormous fins make basking sharks among the most highly valued species in the shark fin market.

Another challenge that comes with their size is their long gestation and development period. These factors make population recovery incredibly slow, which is another reason why protecting these species is so important.

PSRF: Tag, Track, Protect

PSRF is a nonprofit that actively works to generate more data on sharks. While basking sharks are a big part of the foundation’s focus, Van Sommerman points out that species like the blue shark, Prionace glauca, are also under threat. One of the main ways to source more data is by tagging sharks. When sharks are tagged, it provides a baseline of data that informs conservation efforts on how to manage and protect vulnerable populations. Van Sommerman actually got his start in the marine world by tagging fish. Through his time on a boat, he actively learned more about sharks and their endangerment due to factory ships and overexploitation, and as he learned, he became more interested.

Currently, population levels are difficult to establish, and basking sharks are listed as Endangered globally by the IUCN Red List. “Data deficiency is a reason to say, ‘Hey, there is not enough data to even protect these sharks.’ I can only hope that through these projects, people will recognize the importance of these efforts,” Van Sommerman adds.

Fins and Fears

Given that PSRF is one of the oldest shark conservation groups, why has action for basking sharks and other threatened species been so limited? Van Sommerman believes the media misrepresents sharks and that, naturally, people are instinctively wary of predators. He comments on the music for Jaws: “I am no musician, but the scary music never helps.”

To better understand some of the biggest misconceptions about sharks and why they persist, I asked Van Sommerman for his viewpoint. “One of the biggest misconceptions is how big sharks get, how aggressive they are, and how abundant they are; a lot of the basic information is not usually correct,” he says. Most of the time, he notes, basking sharks are usually pretty indifferent to people.

People who fear sharks, a condition known as galeophobia, usually do so because of a fear of the unknown. Movies like Jaws and Sharknado often portray sharks as vicious predators. In reality, most species pose little to no threat to humans. “A majority of sharks are not something that humans have to worry about. In fact, livestock and pets kill more people on average in the U.S. each year than sharks do,” Van Sommerman says.

With some people, though, he says the fear is almost nonexistent, and that can lead to problems. “Don’t get me wrong, they are still animals and can hurt you by accident; the ocean is the last place people should seek out to be careless.”

One Last Look

Van Sommerman notes that restoring these species requires a group effort. He called for all mariners, researchers, and sportsmen to record and report the locations of basking sharks to the office of the Pelagic Shark Research Foundation. The sooner we establish a population baseline, the sooner we can implement effective conservation efforts for these vital species.

For Van Sommerman, it was his grandfather who opened his eyes. Not only to the ocean, but also to the world’s deep interconnectedness. In the beginning, Somerman adapted quickly to fishing and felt at home at sea. However, he still felt he had not yet “located himself on the map”, as he put it. One day, he stood beside a globe with his grandfather, who traced the way the seas connected all living things. From rivers to estuaries, and whales to fish, his grandfather showed him how all these connected pieces are constantly threatened by human actions.

“It was as if the light turned on,” he recalls with quiet clarity. In that moment, Van Sommerman saw the full extent of the destruction he had begun to witness. Just like his grandfather before him. That clarity, passed down like a family heirloom, is the force behind Van Sommerman’s drive. That clarity defines why he cares, and, in turn, why basking sharks matter.

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