Scientists say preliminary tests indicate radiation didn't cause lesions and other symptoms associated with sickened or dead ringed seals found along Alaska's northern coast last year.
The National Oceanic and Atmospheric Administration says a screening of tissue samples from both healthy and sick ice seals and walruses showed no radiation levels that would have directly caused the symptoms.
Radiation was considered because of the timing and size of the nuclear power plant accident in Fukushima (foo-koo-SHEE'-mah), Japan, that followed a tsunami last March.
In December, NOAA's National Marine Fisheries Service confirmed more than 60 dead seals and 75 diseased seals in Alaska waters. Walruses showed similar symptoms but none of them died.
Outbreaks were also reported in Russia and Canada.