The Navy's Northern Edge training exercise has been held in Alaska every two years. This exercise involves ships, aircraft, ordnance, and the widespread use of sonar across more than 42,000 square nautical miles of the marine environment of the Gulf of Alaska. It may drop bombs, launch torpedoes and missiles, and engage in other activities that may poison the Gulf waters.
Many Alaska towns on the Gulf are very concerned about the effects of these activities have on the towns and have protested to the Navy with little effect. First of all, these exercises threaten their livelihood which is based on fishing, the single largest private sector employer in the state of Alaska, providing over 63,000 jobs. The activities threaten four areas protected for reasons of environment conservation. The Navy has produced an Environment Impact Statement which acknowledges that fish in the area are at risk of chemical exposures of various sorts because the war games will introduce chromium, lead, tungsten, nickel, cadmium, cyanide, and ammonium perchlorate, along with numerous other heavy metals and toxic substances, into Alaskan waters. The statement also states that more than five tons of toxic materials could be introduced into the fertile fishing areas of the Gulf each time the Navy conducts a training event. The sonar aspect generates audible blasts up to 235 decibels -- humans begin to suffer hearing damage at 85 decibels -- that travel for thousands of miles across the ocean
After the 2015 exercise, Alaska witnessed the single largest whale mortality event ever to occur in its waters. Statewide, in the year that followed, Alaska had its worst pink salmon fishing season in four decades. A federal disaster declaration was even issued to give salmon fishermen some relief, deferring the repayment of loans. That year also saw the biggest die off of Murres, a small seabird, ever recorded in the state.