A federal marine agency, in partnership with the Navy, yesterday said it completed a pioneering research effort during recent Rim of the Pacific wargames off Hawai'i to gauge the reaction of marine mammals to the military maneuvers.

The National Oceanic and Atmospheric Administration research comes as the Navy and environmentalists continue to battle over the effects of active sonar on whales and dolphins.

Lawsuits have led to restrictions on mid-frequency sonar use off Hawai'i and California during some anti-submarine warfare exercises. In June, the U.S. Supreme Court announced it would step into the dispute.

Environmentalists most recently pointed to the use of Navy sonar during Rimpac exercises in the July 28 stranding and subsequent death of a 15-foot Cuvier's beaked whale on Moloka'i.

The Navy said there is no evidence that sonar affected the 2,500-pound deep-diving whale.

During the recent study in conjunction with Rimpac, scientists for the first time attached listening and movement sensors to marine mammals during military operations.

Almost 40 individual mammals of four different species were tagged with satellite-linked and underwater listening devices.

Operating from a NOAA research vessel and smaller boats during the monthlong naval exercise, scientists placed monitoring tags on deep-diving beaked whales, melon-headed whales and false killer whales, the agency said.

Some devices recorded short-duration information about how the animals move and the sounds they make and hear. Others will continue to provide longer-term data.

"It will take some time to analyze the data and see what conclusions may be drawn, but in many ways this effort lays the foundation for more sophisticated collaborative efforts in the future," said Brandon Southall, director of NOAA's Ocean Acoustics Program.

DANGER TO WHALES

Scientists will use the data culled in the $500,000 study to try to learn more about deep-diving whales and how they might respond to military sonar.

Active Navy sonar systems produce intense sound waves that can reach 235 decibels.

According to the Natural Resources Defense Council, evidence of sonar's dangers surfaced in 2000, when whales of four different species stranded themselves on beaches in the Bahamas after a U.S. Navy battle group used mid-frequency sonar.

Some beached whales have suffered physical trauma, including bleeding around the brain, ears and other tissues, according to the NRDC.

In addition, many have shown symptoms akin to a severe case of "the bends" — the illness that can kill scuba divers who surface quickly from deep water, the organization said.

The Navy, which said active sonar training is crucial to its ability to detect quiet foreign diesel electric submarines, emphasizes that it takes multiple precautions to look out for whales and dolphins during training, and powers down sonar if the animals are encountered.

Scientists also admit little is known about the exact effect of sonar on marine mammals.

NECROPSY FINDINGS

NOAA said there are typically about two dozen whale or dolphin strandings a year in Hawai'i. The July 28 stranding was the eighth this year.

A team of NOAA-contracted veterinarians, Hawai'i Pacific University researchers, and NOAA biologists performed a necropsy on the male beaked whale that stranded on Moloka'i.

The animal did not show any signs of ship strike or fishery interaction, and initial observations showed it was in "good body condition." NOAA did say there were concerns about the condition of the kidney, liver, lung, and urine, but it's still too early to determine the cause of the stranding.

Wende Goo, a NOAA Fisheries Service spokeswoman, said tissue samples are being sent to labs on the Mainland for further analysis.

"We're still waiting, and we probably will be in this waiting mode (for final results) for weeks, at least," Goo said.

NOAA Fisheries determined that the use of midfrequency Navy sonar was a "plausible, if not likely" contributing factor to the mass stranding of up to 200 melon-headed whales in Hanalei Bay, Kaua'i, during Rimpac naval exercises in 2004.

NOAA's Southall, one of several contributors to the finding, later said the report did not conclude that Navy sonar caused the stranding. "We do not know what caused it," Southall said.