NORFOLK, Va. – Debate has long raged over how the military’s use of sonar to detect enemy submarines affects dolphins and whales, which use sound to navigate and locate food.

Now, researchers are moving closer to getting some solid answers.

In a scientific first, experts tagged whales with sensors to track their movement and behavior while Navy ships operated nearby.

The research in Hawaii coincided with the Navy’s monthlong Rim of the Pacific exercise, which ended in late July.

About half the tagged animals were pilot whales. Other species included melon-headed whales, false killer whales and Blainville’s beaked whales.

“This was the first time that we were ever able to tag these animals around realistic military exercises,” said Brandon Southall, director of the ocean acoustics program for NOAA’s fisheries division and a co-sponsor of the study.

It will likely take months to compile the data from the sensors so that the whales’ behavior can be compared to detailed information on when and where the Navy ships were using sonar. Even then, Southall said, the data won’t be conclusive. But it is a starting point, and he expects whale tracking projects to coincide with Navy exercises in coming years.

Environmental groups have successfully sued the Navy to limit its use in the Pacific of midfrequency, active sonar – the technology warships depend on to detect enemy submarines.

Studying deep-diving whales isn’t just physically difficult; it requires researchers to get special permits from the government and follow strict protocols to ensure that the mammals aren’t harmed.

Last summer, NOAA began a three-year study of whales on a 600-square-mile instrumented Navy training range in the Bahamas.

Researchers used the same technique – a long pole and suction cups – to attach archival tags to whales.

“It’s harder than it would seem,” said Southall, who did some of the tagging. “It’s sort of an art.”

The training range, outfitted with underwater hydrophones, allows scientists to plot out a single tagged whale’s movement – after the fact.

The archival tags detach after a few hours, and must be retrieved to access the recorded data. The information gives researchers “exquisite detail” of a single animal over a short time.

In Hawaii, Southall said, the teams used more satellite tags, which stay on for up to a month. Satellite tags don’t have to be retrieved, and they provide almost real-time information when a whale is on the surface.

The two tracking techniques complement each other, Southall said. But the biggest difference between the Bahamas and Hawaii experiments is the exposure to actual sonar.

In the Bahamas study, researchers used a recording of sonar, not the real thing.

The second phase of the Bahamas research begins later this month, and runs through early October.

Southall said scientists and Navy brass want to know more.

“We both have common interests in getting a scientific explanation of what’s really going on with this, and what we could learn that will help us manage the system better,” he said.

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(c) 2008, The Virginian-Pilot (Norfolk, Va.).

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Distributed by McClatchy-Tribune Information Services.

AP-NY-08-04-08 1942EDT

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