The future for sea animals looks pretty grim. And, according to the International Union for Conservation of Nature (IUCN), it will only get worse unless action is taken to conserve sharks and rays.
A new global study released this week predicts that a quarter of chondrichthyan fishes—sharks, rays, and chimaeras—are threatened with extinction.
The study, conducted by a panel of 302 experts from 64 countries, was the first global analysis of the fish class. It was led by the IUCN’s Shark Specialist Group.
“Previous marine studies are based on stock assessments that are taxonomically and geographically limited,” said Nick Dulvy, a researcher at Simon Fraser University in British Columbia, Canada, and co-chair of the IUCN’s Shark Specialist Group.
“Many older studies are based on North American populations, and only on the most abundant fish in the world.”
The group found that only 23 percent of this large class of fish is listed as “least concern” on the IUCN Red List of Threatened Species. Of the 1,041 known species of chondrichthyan fish, 25 are listed as critically endangered, 43 are endangered, and 113 are vulnerable to extinction. This is the worst reported status for any major vertebrate group except for amphibians.
The Big Threats
The report suggests that overfishing, habitat loss, persecution, and climate change are the major threats to the class. Even worse, it mentions that the assessments—partially based on fisheries catching data, which are notorious for underreporting fish counts—may even be “downplaying the true risk” of these threats on sharks and rays.
The species of rays and sharks with a higher risk of extinction live in the shallow waters of the Atlantic, Indian, and western-central Pacific Oceans. Shallow waters are located closer to fisheries and are prone to overfishing. Additionally, many ray species are closer to extinction than sharks are.
“Of the sharks and rays caught and reported to the United Nations, the catch has been dominated by rays for the last 40 years and we never noticed,” he said. The threat of overfishing is not a new phenomenon. Several species of rays have been going under the radar of the fisheries for years. But the new data suggests how these rays are slipping through the system.
Dulvy gave an example: Fisheries are responsible for submitting catch landing data. When two different species are categorized as one species, then one ray could be overfished while the other one increases. According to Dulvy, this miscommunication error has led to the extinction of several different species of rays.
“Retrospectively, we’re finding that species are disappearing, and it’s because we haven’t taken the time to properly identify them,” he said.
Fortunately, the results of the study weren’t all doom and gloom. Dulvy indicated that collaboration within the scientific community, which had developed as a result of the global study, will likely pave the way for stronger conservation efforts around the world. The plan is to use this data to teach government and biodiversity agencies about the immediate threats to sharks and rays.
The group recommends that improved management of fisheries and trade could help promote population recovery. The entire study can be read online at eLife.
For more on the conservation of marine life, read “Foreign Fisheries Contribute to Marine Mammal Deaths.”
“It’s not paper that conserves species, it’s people. Now 300 people that understand the population status of the sharks and rays can go back to their governments and encourage action to conserve these species,” said Dulvy.
Forget circumnavigating the globe in 80 days—an albatross can do it in a mere 46!
These world travelers are among the largest flying birds, weighing up to 25 pounds (11 kilograms), and with a wingspan of 11 feet (3 meters). But hefting such huge bodies off the ground takes a lot of energy. If albatrosses flew simply by flapping their wings, they would lose about half their body mass fueling that kind of flight.
So how do these kings of the sky complete such long journeys so quickly? It turns out they glide in a specific flight pattern that allows them to harness wind energy, gliding right above the sea’s surface to stay aloft, according to a study published in the Journal of Experimental Biology.
Coasting Through Life
A team of scientists from the Technische Universitat Munchen in Munich, Germany, used aerospace engineering to reveal the birds’ unique flight patterns—a physical feat that has puzzled academics for years. By attaching GPS trackers to 20 wandering albatrosses (Diomedea exulans) in the wild, the researchers were able to study data from 16 of the birds as they left and returned to the Kerguelen Archipelago (map) in the Indian Ocean.
Albatrosses yo-yo up and down in the sky, taking advantage of momentum generated on their downhill glides in order to climb back up against the wind. These constant up and down changes in altitude keep the birds aloft without requiring much effort. In fact, the propulsive force generated by such undulations is about ten times greater than anything the albatross could create by simply flapping its wings.
Working Harder, Not Smarter
But it’s a trick the rest of the animal kingdom doesn’t often use. For example, hummingbirds weigh about 0.07 ounces (2.2 grams)—98 percent less than an albatross—and yet their wings have to beat about 70 times per second to keep their little bodies aloft. An albatross can go hours without flapping. Because of this frantic motion, hummingbirds have to eat up to three times their body weight every day.
Even humans struggle with energy efficiency. “An elite cyclist at 60 percent of his maximum aerobic rate can only support 15 to 30 percent of his energy needs with consumed sugars,” according to a LiveScience article. That means we have to refuel more often than the albatross, which can travel greater distances without working as hard.
While it took Jules Verne’s characters just over two and a half months to circumnavigate the globe, an albatross can do it in about half the time. Phileas Fogg and his trusty sidekick Passepartout just can’t compete with these fantastic flyers!