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Inventor says device could call crab to dinner, aid fishermen

Posted: Monday, December 17, 2001

ANCHORAGE (AP) -- No one calls king crabs like hogs to slop. But that's only because no one's ever tried, says Anchorage businessman and inventor Hal Thompson.

''Everybody's been fishing for crab and lobster with bait, the same way for hundreds of years,'' Thompson says.

His idea is to focus on sound, one he says crabs find irresistible: the sound of crabs eating.

''We've actually seen them push aside a chunk of bait to get at the crab making that sound,'' Thompson said. ''We dropped a piece of herring on one crab, and as soon as it started chewing, four others rushed at it, flipped it over, and started taking food from its mouth.''

Thompson says conversations with baffled fishermen led him to develop a sound-based crab lure that broadcasts the munching sound of feeding crabs. If it works as well as Thompson anticipates, it could make for a quicker, safer and cheaper harvest in Alaska's $125 million crab fisheries.

''You wouldn't take more crab because the quotas would still be in place,'' he said. ''But this would make it more efficient. They might get their take in three days instead of a week.''

Sherry Tamone, a shellfish physiologist and an associate professor at the University of Alaska Southeast in Juneau, has seen Thompson's lure at work. She is skeptical but curious.

''It definitely changed their behavior,'' Tamone said. ''They moved toward it at times and, at times, away.''

Crabs and lobsters don't have ears but pick up pressure waves through hairlike sensory organs on their bodies. Much work has been done on how crabs sniff out waterborne scents, Tamone said, but little on their response to sound.

Alaska SeaLife Center curator Richard Hawking says the newness of research into underwater sounds is what makes Thompson's lure so intriguing.

''Many animals that live in water are very sensitive to sounds, but we just don't listen to them,'' Hawking said. ''We tend to rely more on what we can see.''

Hawking was not on hand when Thompson tested his equipment on crabs at the Seward Sea Life Center, but his impression, like Tamone's, was that the results were still inconclusive.

''We took it at face value. It wasn't a full research project,'' Hawking said.

Crab boat captain Walt Mezich of Anchorage is skeptical. But being a crabber, he's willing to give anything a shot. He recently worked in the Florida stone crab and lobster fishery. While there, he developed a theory.

''I know the only way you can catch a lobster is by noise,'' Mezich said. ''Down there, they put a little lobster in the pot, 'cause the lobsters go for safety, not food. They go by and hear a lobster and think, I'll go in there and be safe.' ''

''Think'' is just a figure of speech when you're talking about a critter that is literally brainless. Nevertheless, Mezich says he'll give Thompson's lure a try when it's available.

He doesn't expect it to change his approach. ''I hang more bait in my pots than anyone,'' he said. ''I've always said the more hanging bait you've got, the more crabs you get.''

Thompson began thinking about how to attract crabs in the 1980s, when he heard fishermen wondering why crabs seemed to respond better to actual bait than to scent alone. To Thompson, this suggested that crabs somehow communicate when they find food. Then, in 1998, he came across a zoology book that described how crabs respond to meat juice.

''It mentioned how excited they became and the click they make,'' Thompson said. ''That's when I said, Ah-ha!'

''My theory is that they inadvertently let other crabs know there's food around. The pot with scent attracts only by scent. If there's food, crab (munching) is calling other crabs.''

With the help of the Institute of Marine Science in Seward, Thompson recorded the feeding clicks of king crabs onto a CD. Then Seattle-based American Production filtered out extraneous noises.

Tests on dungeness crabs at the Institute of Marine Science in Washington showed that while they responded to king crab feeding sounds at some frequencies better than others, ''all of them worked,'' Thompson said.

He and several friends have incorporated in Alaska as SOMATE Corp. and signed a contract with a New Hampshire company to build prototypes for open-water testing in exchange for an exclusive right to build commercial units. They will be about the size of a flashlight, run off a single D-cell battery and contain a flash memory chip, amplifier and speaker, all packaged in a housing good to depths of 1,000 feet.

Thompson thinks the device will work better in combination with bait and in open water without the echoes found in tanks.

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