Scientists are asking ocean-goers to keep their eyes open for
the basking shark ---- the world's second-largest fish ---- a
gentle giant with a mouth like a cavern.
The researchers, with the National Oceanic and Atmospheric
Administration and California State University, are gathering data
on the elusive filter feeders, which can grow up to 33 feet
Once common off the California coast, basking sharks have
declined because of fishing operations and eradication programs in
the last century, and are now listed as a "species of concern" with
the National Marine Fisheries Service. The term designates a
creature that may be at risk, but for which there is too little
information to justify a threatened or endangered listing.
Despite their size and global range, scientists know little
about the sharks' life cycle, reproduction or population.
"Nobody knows where they are, or what they're doing or how many
there are," said Owyn Snodgrass, a fisheries technician with the
administration's La Jolla office who is working to track the
Scientists marked one shark with a satellite tag last year and
aim to tag at least two more animals this year in an effort to
glean data on their movements and behavior. They're also asking
anglers, whale-watchers and boaters to keep an eye out for the
sharks, and to report any sightings, along with locations, times
That information, they hope, will help them devise plans to keep
the species from declining further. By defining how many basking
sharks remain, where they go, how long they live, and when they
reproduce, scientists can determine what the creatures need to
"We're trying to learn something about it before people say it's
endangered," said Dave Ebert, program director of the Pacific Shark
Research Center at California State University's Moss Landing
Marine Laboratories on Monterey Bay.
With a hulking body and gaping maw, the basking shark looks
formidable, but makes its living by straining tiny crustaceans,
called copepods, through gills that flare out from its head, making
it look, said Ebert, "like a giant pollywog."
It can strain up to 2,000 gallons per hour of the plankton and
seawater through a mouth large enough to swallow a human, he
"I don't know why anybody would want to, but you could swim into
their mouth. It would probably be the last thing you do."
Although they are second in size only to tropical whale sharks,
and share that species' passive feeding system, basking sharks are
actually closely related to some of the ocean's most aggressive
predators, including great whites and makos.
They're found in waters around the globe, and studies on
Atlantic sharks showed that animals tracked in Massachusetts have
migrated to Europe or south to Brazil, Ebert said.
"You basically have a large fish that uses the entire ocean
basin in the Atlantic, and that's probably what we have here" in
the Pacific, he said. "They may migrate to Japan, or to South
Although they're seen infrequently, they sometimes congregate in
large groups, and have appeared by the hundreds in the Atlantic
Ocean off Scandinavia and in the Pacific near Vancouver Island,
Despite such occasional mass sightings, the animals have grown
scarce in recent decades. Researchers said thousands were killed in
fishing and eradication programs in the 1900s, and the slow-growing
species never recovered.
Heidi Dewar, a fisheries biologist with NOAA, said that between
1940 and 1970, Canadian fishermen killed the sharks using a device
called a "razor-billed shark slasher" to prevent their entanglement
in salmon gill nets.
"They designed a big knife that they would attach to the front
of boats," she said. "It would ram the animals and cut them in