The whale died Thursday near Cape Lookout, a part of a national seashore reachable by boat or helicopter.
Employees from the National Oceanic and Atmospheric Administration's Fisheries Service have started a necropsy to try to determine why the 2-year-old whale stranded on the island off Morehead City.
Blair Mase, marine mammal stranding coordinator for NOAA's Southeast region, told The Daily News of Jacksonville that euthanizing the whale was the best course of action.
"It was in poor condition," she said. "It had been on the beach since Monday and had started to feel the effects."
Mase said a pilot flying over the area reported the whale Monday. Weather conditions prevented NOAA from sending a crew by boat immediately, but the Coast Guard sent a veterinarian and others by helicopter Wednesday.
"They went out while the tide was at its lowest and the helicopter was able to land on the sandbar but they weren't able to stay long," Mase said.
In December, a newborn right whale was euthanized after it became stranded on an Outer Banks beach in Dare County.
A biologist said the 15-foot baby whale was in poor condition and couldn't survive without its mother.
North Atlantic right whales are an endangered species, and officials believe there are only about 350 to 400 left.
