A pygmy killer whale washed up on an O'ahu beach over the weekend as the Navy carried out maritime exercises in Hawaiian waters. But the elderly animal died of an illness and not because the military was using a type of sonar that may harm marine mammals, a federal official said yesterday.

Initial findings from a CT scan and a necropsy show a lung infection that had spread to the heart and the brain killed the whale, said Chris Yates, assistant regional administrator in Hawai'i for the National Marine Fisheries Service.

The 7-foot, 200-pound animal also had a large amount of fluid in its chest and suffered from a curved spine, or scoliosis.

"It was an old, very sick animal that came ashore, which is what most strandings are," said Yates.

The fisheries service learned of the stranding on a rocky ledge at Makapu'u beach Sunday morning after someone called the marine mammal response hot line. Officials examined the whale later that day.

The fisheries service said the whale appeared to be one of some roughly two dozen or so sickly whales found stranded in the main Hawaiian Islands during an average year.

Yates said there was no sign the animal's death was related to the Rim of the Pacific, or Rimpac, exercises the Navy has been conducting in Hawai'i waters with seven other countries.

The 20th multinational exercise ends this week after a month of war games conducted off Hawai'i and a high-profile legal battle with environmentalists over the use of active sonar.

The force comprising eight nations, 35 ships, 160 aircraft and 19,000 personnel is returning to Pearl Harbor for a short stay before beginning the final journey home at the end of the month.

"The exercise was a tremendous opportunity to learn and improve how we work together," Vice Adm. Barry Costello, commander of the U.S. Navy Third Fleet, said in a release. "But more importantly, Rimpac continues to build positive relationships among allied nations."

Over a period of 10 days, the Rimpac forces operated in waters off O'ahu and Kaua'i and conducted numerous exercises including live missile, torpedo, and gunnery fire exercises, air defense, surface warfare, undersea warfare, maritime boardings, mine warfare, and anti-submarine warfare.

Part of this year's Rimpac also played out in the courts, and the Navy and environmental groups in early July reached an agreement lifting a federal court restraining order and allowing the Navy to conduct midfrequency active sonar training during the war games.

The agreement included restrictions on sonar use to improve protection of marine mammals and to keep the sonar training out of the new Northwestern Hawaiian Islands Marine National Monument.

Among mitigation measures agreed to by the Navy for this year's Rimpac were zones of active sonar exclusion ringing the Islands.

The exception was plans for intensive "choke point" active sonar use between Maui and the Big Island and two spots between Ni'ihau and Kaua'i.

The Navy also had agreed to reduce sonar output by 6 decibels if marine mammals were spotted within 1,100 yards of a ship, a 10-decibel reduction within 550 yards, and complete elimination of active sonar within 220 yards.

The Natural Resources Defense Council on Monday raised concern over a research vessel's report that 400 to 450 melon-headed whales were spotted to the northwest of the Big Island — where the last of the three choke point anti-submarine warfare training exercises was to be held.

Michael Jasny, a senior consultant with the defense council, yesterday said the use of active sonar was not detected in the channel, leading the group to believe the Navy may not have been able to use the sonar because of the whales' presence.

Cmdr. Dora Lockwood, a Rimpac spokeswoman, yesterday said, "We will not discuss the details of the exercise scenario. We complied with all mitigation measures."