PORTLAND, Maine - Marine conservation groups say accidental deaths this year among the endangered North Atlantic right whales threaten the species survival.
Right whales are among the most imperiled marine mammals on Earth. No more than 500 of them still exist in the wild.
Biologist Regina Asmutis-Silvia says at least 12 whales have died since April, or about 2 percent of the population in just a few months.
Asmutis-Silvia and other conservationists say the deaths are evidence that regulations to prevent ship strikes and entanglement in fishing gear need to be strengthened in the United States and Canada.
Marine regulators in both countries say efforts to protect whales are ongoing.