Will ghost sharks disappear before scientists can study them?

Take a look at a ghost shark and you can say, “What about that weird-looking fish?”

In recent decades, scientists have learned that these cartilaginous fish, also known as rat or Chimera fish, have existed for hundreds of millions of years and have venomous spines in front of their dorsal fins and “fly” through the water beating. pectoral fins. They even found out that most male ghost sharks have a retractable sexual organ on their forehead that resembles a medieval mace.

However, much remains to be learned about these strange creatures. Basic biological information, such as how long they live and how often they reproduce, is missing for most of the 52 known species. The absence of this key information makes it difficult to manage and monitor scientists for ghost shark populations, even if there is evidence that some species may be at risk of extinction.

Scientists from the Shark Specialist Group, a division of the International Union for Conservation of Nature, recently assessed the risk of extinction of all confirmed ghost shark species and determined that 16% are “threatened” or “almost threatened”. The assessment, which was published this month in the journal Fish and Fisheries, also found that 15 percent of ghost shark species are so under-studied that their risk of extinction cannot be determined. Now, experts are worried that certain species of ghost sharks may become extinct before scientists have a chance to study them.

Ghost sharks can be found in all the world’s oceans except the Arctic and Antarctic. Most live in the depths, although a handful of species live in shallow coastal waters. Despite their name, ghost sharks are not real sharks, although they are closely related. Unlike their shark cousins, ghost sharks have long, thin tails and large, constantly growing dental plaques, which give them a rat-like appearance. Some have long, slender snouts, while others wear plow-shaped ones, which they use to probe sediments on the seabed for food.

“They have a face that only a mother or a researcher could love,” said David Ebert, director of the Pacific Shark Research Center at Moss Landing Marine Laboratories in California and co-author of the assessment.

Almost half of the species known to science have been discovered in the last two decades alone. “Only now are we beginning to realize that there are many more of these things around than we previously realized,” said Dr. Ebert, whose lab was credited with discovering 11 of the 52 species of sharks. known ghost.

Dr. Ebert is one of only a few scientists currently studying ghost sharks. Securing funding to study them has long been a challenge for scientists.

“Chimeras don’t have much commercial value, so there’s not much interest in getting more information about them,” said Brit Finucci, a fisheries scientist at the New Zealand National Institute of Water and Atmospheric Research and lead author. of evaluation. “They’re also pretty cryptic, so they’re hard to find and hard to study.” Several species of ghost shark, including the Bahamas ghost shark, are known from a single specimen.

Ghost sharks are caught primarily as bycatch. While their meat is edible, most of their commercial value comes from the liver, which contains an oil known as squalene that is used in a wide variety of cosmetics and pharmaceuticals.

Although harvested and sold worldwide, 90% of ghost shark species are not managed, according to the IUCN assessment. This means that those who catch these species are not subject to limits and are not required to share data on their catches.

If fishing fleets continue to venture further into the deep sea, experts fear that some species of ghost sharks may become extinct before scientists even notice that they are in trouble.

“How can we start wrapping our heads around them, preventing them from disappearing if we don’t know anything about them?” said Dominique Didier, an ichthyologist at Millersville University in Pennsylvania.

To prevent the unseen occurrence of ghost shark extinctions, the authors argue, more scientists need to study ghost sharks, and marine authorities need to exercise more oversight and management of ghost shark fisheries around the world.

“We shouldn’t wait,” Dr. Finucci said. “Even if these animals are assessed with a lower risk of extinction, we should not wait until they are in fact an endangered species before we begin their study.”