ANCHORAGE (AP) -- Hiroshi Ueda is a Japanese fish physiologist with a dream: He wants to send a self-propelled ''robot boat'' to follow a salmon on the animal's two-month excursion from Alaska to Japan.
Ueda announced his plan in February in Honolulu at the American Geophysical Union's Ocean Sciences 2002, the world's largest gathering of ocean scientists. Ueda reported that he and Hokkaido University students had launched a successful 8-foot-long prototype in a Hokkaido lake last fall.
For the Bering Sea trip, Ueda envisions a computer-piloted boat roughly the size of a small yacht that would automatically track and follow a tagged chum salmon on its migration back to Japan. Based on observations of Japanese chums, which are abundant in the Bering sea, Ueda has determined the trip should take about 67 days.
He hopes the craft will lead to better understanding of the homing mechanism that brings seagoing salmon back to their freshwater spawning grounds. If successful, the boat is sure to draw other interest from scientists researching the decline of north Pacific salmon populations.
One such scientist is marine salmon program manager Bill Heard, of the Alaska Fisheries Science Center's Auke Bay Laboratory in Juneau. He said an unmanned vessel capable of riding rough seas would have valuable applications in Alaska.
''There's a great dearth of information on salmon behavior in the fall and winter because seas are so rough and it's very expensive to send ships out there,'' he said. ''So this may be a novel idea worth exploring.''
Ueda, the director of the Toya Lake Station for Environmental Biology on Hokkaido, is still fishing for funding. ''Now (the boat) is still a dream,'' he says. He hopes the success of his prototype will attract interest.
In October he and the university students tested the small craft on 5.5-mile Toya Lake. Driven by an ultrasonic tracking system, the boat followed the fish -- one for more than six miles.
On shore, Ueda and the students received its signals, retrieving such information as swimming depth, water temperature and the energy expended by the fish.
Usually, scientists wanting such detailed information must recapture tagged fish -- or rely on fishermen to return them -- in order to learn what was recorded by the surgically implanted data-logging tags.
Ueda's prototype lacked a roof, a feature a Bering Sea vessel would need to withstand strong wind and waves. But it was stable enough to weather choppy waters and quiet enough so as not to spook salmon. Ueda credits the device's buoyancy to Styrofoam.
Ueda's experiments represent the combined efforts of at least 10 experts in multiple technical fields, including ship engineering, acoustic engineering and computer science.
He now hopes to interest collaborators and funders in helping him develop a more robust robot.
The Bering Sea boat would have to carry nearly 265 pounds of equipment, including a gyroscope to keep the vessel level in stormy seas. It would have to employ a telecommunication system between the boat and a land base, where researchers would collect the data.
Ueda sees the robot boat as a solution to the difficulty and expense of oceanographic tracking. But he faces barriers beyond technology -- such as the nature of the sea he proposes to cross.
Among mariners, the Bering Sea has earned a reputation as one of the most dangerous places in the world. Last year the Arctic Rose sank in a raging storm. All 15 crewmembers on board the 92-foot steel fishing vessel died.
Then there is the matter of national borders. There is no way to tell where a fish will go once tagged, its robot boat following close behind across the open sea.
''We need international cooperation between the U.S., Canada, Russia and maybe China,'' Ueda says. If necessary, he will make plans for a backup manned vessel to follow the robot boat, he said, but that is not his preference.
''My dream,'' he said, ''is the boat itself can track the salmon, and we (can) stay on the land.''
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