Four national and international environmental and animal rights groups — citing the appearance of a distressed pod of whales in a Kaua'i bay two weeks ago during Navy active sonar exercises — are asking the Navy to take steps to minimize injury to whales.

The groups, in a letter to be given to Navy Secretary Gordon R. England today, said the powerful sonar signals are "known to be implicated in a growing number of mass mortalities of whales."

The Natural Resources Defense Council, Jean-Michel Cousteau's Ocean Futures Society, Humane Society of the United States and the International Fund for Animal Welfare prepared the 13-page letter.