By Laura Zuckerman
Sept 26 (Reuters) - A federal judge in California has sided with environmental groups in their lawsuit against the U.S. government over Navy training exercises off the West Coast involving sonar that they say harms endangered whales, dolphins and other protected marine mammals.
The ruling, the latest in a long-running dispute pitting whales against the military, requires the National Marine Fisheries Service to reconsider permits allowing the Navy to conduct its exercises in a vast stretch of open waters along the Pacific Northwest coast.
In a 43-page opinion issued late on Wednesday, U.S. Magistrate Nandor Vadas in Eureka, California, found that the Marine Fisheries Service failed to apply the best available science in assessing impacts on whales and dolphins from the Navy's use of sonar.
Environmental groups said similar mid-frequency sonar by the Navy has been linked to fatal mass strandings of marine mammals around the world, including Hawaii, the Bahamas, Greece, the Canary Islands and Spain.
Deafening underwater noise from sonar can also disrupt marine mammals' migration, nursing, breeding and feeding, the plaintiffs argued.
Under the ruling, the Marine Fisheries Service must reassess its permits based on new research from 2010 and 2011 showing that marine mammals are far more sensitive to sonar and other underwater noises than previously believed.
Those assessments could trigger a requirement that the Navy do more to protect whales and dolphins in the training grounds in question, which stretch from northern California to the Canadian border.
A spokeswoman for the marine service, is a branch of the National Oceanic and Atmospheric Administration, said the agency was reviewing the decision. There was no immediate comment from the Navy.
Environmentalists hailed the ruling as a key victory.
"Today's ruling gives whales and other marine mammals a fighting chance against the Navy," said Miyoko Sakashita, oceans director at the Center for Biological Diversity.
The ruling does not order an immediate halt to any Navy training exercises. Instead, it requires the NOAA agency to reevaluate the Navy permits under the terms of the Endangered Species Act and Marine Mammal Protection Act.
The judge gave the agency 20 days to file a court brief suggesting how long it should take to conduct the permit review and how the scope of the reassessment should be defined.
In 2008, the U.S. Supreme Court sided with the Navy in a similar case, ruling that sonar training exercises off the Southern California coast could be conducted without restrictions designed to safeguard marine life. (Additional reporting by David Alexander; Editing by Steve Gorman and Bob Burgdorfer)