Antarctic seals spy on deep water fish

Jan. 18, 2002 at 8:46 AM
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AUSTIN, Texas, Jan. 16 (UPI) -- Weddell seals equipped with new technologies are allowing Antarctic researchers to spy on the habits of elusive deep water fish.

A team of American scientists at a South Pole research site has used the fish-seeking animals to gain new insight into two rarely studied species.

"Initially, the goal of our project was to study the feeding behavior of seals," said Dr. Lee Fuiman, professor of marine science at the University of Texas at Austin and author of a study on the project. "But our data on the fish turned our to be much more abundant than we expected,"

Fuiman and his team of colleagues from Texas A&M University in Galveston and the University of California, Santa Cruz outfitted 15 "seeing eye seals" with a video camera, infrared lights and data recorders that allowed them to track the mammals' interaction with their prey.

The data the researchers collected over the course of three summers showed the fish species -- toothfish and silverfish -- migrate and linger at different depths than previously thought.

The "seal cam" images reveal that silverfish tend to migrate from deeper water to shallow water using subtle changes in ambient light to guide them. Toothfish, a species important to commercial fisheries, were found in shallower waters than scientists had predicted.

The researchers say the new "seal cam" technology is particularly useful for scientific study in Antarctica because the extreme climate renders other deep-sea equipment useless. Approximately 10 feet of ice encloses the Antarctic Ocean and prevents scientists from trawling for fish or using submersible vehicles.

The seals are in many ways the ideal research vehicle because they naturally seek the fish. With slow-moving, remote-controlled submersibles, scientists are left searching for and chasing after the fast-moving fish species.

"Seals are a guided device. They can get down to 700 meters in 10 minutes," Fuiman said. "It's very difficult for us to get down that fast."

Human divers also suffer under Antarctica's harsh conditions. Water temperatures hover at 30 degrees Fahrenheit causing them to tire easily. At best, divers can explore as deep as 100 meters below the surface -- one-seventh of the seal's capability.

Given the clear advantages of employing marine mammal spies the scientists say the technique could be used to observe other isolated species that thrive at great depths.

"Elephant seals on the California coast can go even deeper. Perhaps, we can use other marine mammal species to go even deeper," Fuiman said.

But as with many innovations, the high-tech seals also have their disadvantages, said Dr. John Janssen, senior scientist with the Water Institute at the University of Wisconsin at Milwaukee.

"Seals aren't a random sampler. They've learned something about where they're going to go so what you see through them is limited," he said.


(Reported by Koren Capozza in San Francisco.)

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