The Navy have raised concerns about new sonar restrictions as it finished three days of anti-submarine warfare training off Hawaii — the first such training under a US court order on sonar use that is meant to give better protection to whales and dolphins. The USS Abraham Lincoln aircraft carrier strike group, which conducted the training before its expected deployment to the Persian Gulf region, also included a cruiser, three destroyers and two submarines.

Marine mammals were spotted during the exercise but so far no incidents involving those animals have been reported. It will be several weeks before final reports are completed. Paul Achitoff, an Earthjustice attorney representing several groups that sued the Navy over sonar use in Hawaii waters, said the Navy's claim that it had to devote more time to whale watching than sonar training is "nonsensical." There are at least 1,000 personnel out on the water but the Navy probably only had about ten of them watching out for marine mammals.

Navy sonar use and its effects on marine mammals have become an extremely contentious as it involves using active sonar "pings" to be able to detect an increasing number of quiet diesel electric foreign submarines which is known to kill whales and is still an extremely complex issue on which there is still much uncertainty. The preliminary injunction put in place required the Navy to implement eight mitigation measures including the need for the Navy to power down active sonar by 6 decibels when a marine mammal is spotted within 1,500 meters of a sonar-emitting vessel. The sonar power must be stepped down the closer the animal is, and within 500 metres, all sonar transmission must cease.

At least 26 species of marine mammals frequent Hawaii’s waters including humpback whales. Additional anti-submarine exercises are planned for May and June.