Experts say sonar probably stranded whales

WASHINGTON — Federal marine specialists have concluded Navy sonar was the most likely cause of the unusual stranding of melon-headed whales in a Hawaiian bay in 2004.

The appearance of up to 200 of the normally deep-diving whales in Hanalei Bay in Kauai occurred while a major American-Japanese sonar-training exercise was taking place at the nearby Pacific Missile Range Facility.

The report is the latest in a series of scientific reviews linking traditional midfrequency naval sonar to whale strandings. The sonar has been used for decades, but it was only recently that an apparent connection to strandings was established.

While the National Oceanic and Atmospheric Administration (NOAA) scientists said they could not definitely state that sonar caused the strandings, they said extensive study led them to the conclusion there was no other likely cause.

"Our analyses indicate there was no significant weather, natural oceanographic event or known biological factors that would explain the animals' movement into the bay nor the group's continued presence in the bay," said Dr. Teri Rowles, NOAA Fisheries Service's lead marine-mammal veterinarian and lead author of the report.

NOAA concluded sonar was "a plausible, if not likely, contributing factor" to the stranding.

The Navy has said it was virtually impossible for its sonar to have led to the Hanalei Bay stranding, and officials maintained that position Thursday. "I think that if you look at the report, there are just so many unknown factors at work that to say sonar was a 'plausible if not likely' cause is erroneous," said Lt. Commander Christy Hagen of the U.S. Pacific Fleet in Hawaii.

The Navy is planning another major sonar-testing maneuver in the same area in July and — for the first time — NOAA has formally asked the Navy to use expanded measures to protect whales from the possible effects of its sonar.

The active sonar used by navies around the world sends out loud pings that appear to frighten and disorient whales, especially deep-diving species such as the beaked and melon-headed whales.

The effect was documented off Greece in 1996 and established later during naval exercises in the Bahamas, off the Canary Islands and recently off Spain.

The findings have complicated the Navy's efforts to set up a 500-square-nautical-mile sonar-training facility off the coast of North Carolina. Naval officials say the sonar training is essential.

Rowles said the melon-headed stranding in Hawaii was highly unusual, and only the second recorded in the United States in modern times. The other occurred off Florida earlier this year, and Rowles said NOAA is trying to determine if any naval activity occurred in the area before the stranding.

Rowles and other NOAA scientists said it is difficult to determine why whales behave as they do.

In the 2000 Bahamas stranding, a local marine biologist collected some of the whales that died onshore and froze them for later study — which helped NOAA conclude sonar was the likely cause.

In Hanalei Bay there was no physical evidence to examine.

Thursday's NOAA conclusion was based instead on the lack of other possible causes, the unusual nature of the whale movement and an analysis that concluded the extensive sonar use occurred close enough to Hanalei Bay for the whales to swim there by early July 3, when they were first seen.