HONOLULU -- U.S. Navy training and testing could inadvertently kill hundreds of whales and dolphins and injure thousands over the next five years, mostly as a result of detonating explosives underwater, according to two environmental impact statements released by the military Friday.

The Navy said that the studies focused on waters off the U.S. East Coast, the Gulf of Mexico, Southern California and Hawaii from 2014 through 2019, the main areas where it tests equipment and trains sailors.

The studies were done ahead of the Navy applying to the National Marine Fisheries Service for permits for its activities.

Most of the deaths would come from explosives, though some might come from testing sonar or animals being hit by ships.

Rear Adm. Kevin Slates, the Navy's energy and environmental readiness division director, told reporters this week the Navy uses simulators where possible, but sailors must test and train in real-life conditions.

According to the reports, computer models show training and testing may kill 186 whales and dolphins off the East Coast and 155 off Hawaii and Southern California.

Off the East Coast, there could be 11,267 serious injuries and 1.89 million minor injuries like temporary hearing loss. The reports also said the testing and training might also cause marine mammals to change their behaviour -- such as swimming in a different direction -- in 20 million instances.

Off Hawaii and Southern California, the reports said that the naval activities may cause 2,039 serious injuries, 1.86 million temporary injuries and 7.7 million instances of behavioural change.

But Michael Jasny, senior policy analyst at the Natural Resources Defence Council, said the Navy was underestimating the effect its activities on marine mammals.

He pointed to a study by government and private sector scientists published just last month in the journal Proceedings of the Royal Society showing mid-frequency active sonar can disrupt blue whale feeding. The study says feeding disruptions and the movement of whales away from their prey could significantly affect the health of individual whales and the overall health of baleen whale populations.