MELISSA BLOCK, Host:
You are listening to ALL THINGS CONSIDERED from NPR News.
This year, the federal government declared that basking sharks in the Pacific Ocean are a species of concern. That means the government doesn't have enough information to say the giant fish is threatened or endangered, but it might be. And when we say giant fish, we aren't exaggerating. The basking shark is about the length of a school bus.
Here's NPR's Joe Palca.
JOE PALCA: Fisheries research biologist Heidi Dewar is a serious scientist. But when she describes why basking sharks are interesting to study, technical language just won't do.
HEIDI DEWAR: They're just really cool and amazing-looking and beautiful.
PALCA: Dewar works for the National Oceanic and Atmospheric Administration's fishery service in La Jolla, California.
DEWAR: There's nothing like just driving up in a boat to one of these monstrous, brown creatures slowly, gently, peacefully swimming through the ocean.
PALCA: Dewar says basking sharks can grow as long as 30 feet or more, and, of course, they have that distinctive dorsal fin that can poke out of the water when they're near the surface. You might find it intimidating to be anywhere near a 30-foot long shark, but Dewar says you really don't have to worry about being attacked by a basking shark.
DEWAR: Similar to the other large elasmobranchs, like whale sharks and manta rays, they're filter feeders.
PALCA: Yes, she said elasmobranchs.
DEWAR: Elasmobranchs are the sharks and rays, that's the subgroup of fish that sharks and rays fall into.
PALCA: Got that?
Instead of swimming after their dinner, basking sharks just open their cavernous mouths. Comb-like structures called gill rakers filter tasty critters like krill out of the water for the sharks to dine on. The sharks do have teeth but not the kind that would inspire fear.
GREG SKOMAL: If you took a grain of rice and cut it in half, that's what the teeth of a basking shark looks like.
PALCA: Greg Skomal is a shark specialist with the state of Massachusetts Division of Marine Fisheries. He says basking sharks probably don't use their teeth at all for eating.
SKOMAL: However, I do think they're used by the males to grasp onto the females during courtship and during mating. So I do believe that the teeth aren't completely useless.
PALCA: Skomal has been studying the sharks in the Atlantic. He says until recently, scientists thought the sharks mostly stayed in the cooler Atlantic waters off North America. But over the last decade, satellite tracking data have told a different story.
SKOMAL: Here, we have a species that we thought was largely a cool water animal, migrating down south into tropical waters as far south as South America and as far south as south of the equator.
PALCA: NOAA's Heidi Dewar says that now that her agency has declared the basking shark a species of concern, there's a pot of money for doing similar tracking studies for the sharks in the Pacific. She's not only interested in whether the sharks are swimming north and south along the eastern Pacific shoreline, but also...
DEWAR: If they're traveling across the Pacific and consequently interacting with high seas fisheries or with fisheries over off of Japan or China or Taiwan.
PALCA: Dewar says there's a concern that Asian fleets might be taking the shark for its prized fins. She says the effort to protect the basking shark has implications that go beyond a single species.
DEWAR: You know, one thing about this charismatic megafauna is that I think they really help people to connect with life in the ocean.
PALCA: Connect in a way, it's clear, Heidi Dewar already has.
Joe Palca, NPR News.