Shrimp study finds unexpected crowd in Willapa:sharks

<I>Photo provided</I><BR>A bluntnose sevengill shark photographed by researchers in Willapa Bay was an indication that the bay still holds surprises.

WILLAPA BAY - Many people are under the impression that science is straightforward: A question is asked and researchers using various techniques strive to find the answer.

But that search through the maze of the unknown, like a tourist winding their way through an unfamiliar city, often leads to some delightful and unexpected discoveries.

Last month researchers working with the Washington State University Long Beach Research and Extension Unit, as part of a burrowing shrimp control study, set up underwater video cameras to try confirm their speculations that sturgeon were feeding on the shrimp, creating 1-foot square by 1-foot deep pits in the mudflats in the process.

"We were watching the video and up swims a big monster shark that fills the frame," said Kim Patten, researcher with the extension unit.

Although they didn't find the information they were looking for - these sharks, bluntnose sevengills (Notorynchus cepedianus), do not feed on burrowing shrimp - the researchers were thrilled none the less.

"The new footage got a lot of people excited," said Dale Versteegen, an international graduate student from Latrobe University in Australia working on the equivalent of a U.S. masters degree. Part of the surprise, he said, is the cameras are suspended in about six feet of water when the tide is out. He estimates the sharks, at least two males have been spotted, are about seven-feet long.

To find out more about their unexpected visitors, the research team contacted Greg Bargmann, research scientist with the Washington Fish and Wildlife Department. He has been studying the sharks, although this is the last year of his study. He said the footage is the first of its kind to record the behavior of this type of shark in their natural environment.

Over the past three years, he has radio tagged about 40 sevengill sharks and marked an additional 20 with plastic disc tags. He said they generally appear in the bay around March and leave again in October. One female he tagged arrived in July, left in October, and was detected in Southern California in November, quite a journey in a short amount of time.

"I'm impressed with their abundance," in the bay, said Bargmann. Fishermen should be pleased by the number of sevengill sharks as well, seals are high up on their menu of preferred food although they will take salmon given the opportunity. The sharks' arrival and departure coincides with the seals' breeding season, and the sharks can be found in larger numbers where there are seals.

As a group, sharks are amazingly diverse and fascinating. Occasionally, some new species are still being discovered. Despite their ferocious reputation, and although they have a spine, they do not have a backbone. They are classified under the class chondrichthyes, or cartilaginous fishes that lack true bones. Included in that group along with sharks are skates and rays.

Although sharks are notorious for their meat-eating ways, the largest shark, commonly called a basking or whale shark, actually eats plankton.

Unlike many fish, sharks do not spawn. The male has modified pelvic fins which he uses to "clasp" the female and fertilization takes place internally.

Gestation for various species can last anywhere from several months up to two years. Some sharks lay egg cases. When mature, the shark pups hatch out of the case and are on their own. Sometimes these cases wash up on beaches, their fanciful shapes inspiring the name of "mermaid's purse." Other sharks, like the sevengill, give birth to live pups, which become independent at birth, quickly swimming away so they don't become a snack for mother. In addition to the attraction of a food source of seals, the sevengills also give birth in Willapa, using it as a nursery.

As their name implies, sevengill sharks have seven gill-slits instead of the common five on either side of their bodies. They are found in all oceans of the world except the north Atlantic and he Mediterranean. Their backside is silver-gray to brownish and their bellies are light or cream colored. Individuals can be distinguished by the variation in their dark spots, which gives rise to another common name for them, the spotted cow shark.

Sevengills have been known to hunt in packs to capture prey such as seal and other sharks. Other interesting behaviors include a complex courtship ritual.

Like many large top predators, sharks are long-lived and slow to reproduce. Sevengill sharks have been known to live 50 years. Unfortunately, this leaves them vulnerable to overfishing and extinction. In fact, worldwide, shark populations are crashing, some populations reduced by an estimated 75 percent.

` They are being decimated by incidental catch, becoming tangled in fishing nets, and the increasing demand for sharkfins, considered a delicacy in some cultures. In some areas, the sharks are caught, their fins are sliced off while the shark is still alive, and the rest of the fish is dumped overboard to die.

Slowly, people are beginning to realize the importance of sharks, that they are not the mindless and destructive man-eating menaces often portrayed to the public. They are an integral part of maintaining the oceans' balance with complex behaviors and an innate curiosity not apparent in their flat alien eyes.

In Hawaii recently, lifeguards helped rescue a shark entangled in a fisherman's net, successfully releasing it back to the ocean. In South Africa, members of a local tourism trade sent a letter of protest along with pictures of dead sharks caught on a line to their government, explaining they were concerned such practices would drive away tourist, who come specifically for the natural setting a perhaps a rare glimpse of a shark.

Even Peter Benchley, a devout amateur marine biologist himself and author of the horror-thriller Jaws, has admitted to regretting adding fuel to the cultural phobia surrounding sharks.

Little is known about sharks, despite their prominent place is current cultural mythology. Which is why the recent video of the sevengill in Willapa Bay is attracting attention and excitement. That information will add to the knowledge of sharks and perhaps help better manage their populations. One thing is certain, though. More sharks mean fewer seals.

To find out more about sharks, visit the Florida Museum of Natural History Ichthyology Web site at www.flmnh.ufl.edu or the University of Michigan Museum of Zoology Animal Diversity Web site at http:/animaldiversity.ummz.umich.edu or the Elasmodiver Web site at www.elasmodiver.com.

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