(CNN) Two more gray whales were found dead this week in Alaska amid the mysterious surge of deaths within the species this year along the US West Coast, CNN affiliate KTUU reports.

That makes seven in Alaska and at least 75 total, in what the National Oceanic and Atmospheric Administration calls an " unusual mortality event ," the station reports.

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One of the two found near Kodiak Island in the Gulf of Alaska showed signs of killer whale "predation," KTUU reports.

Two more were discovered this week off Washington state.

Last month, ocean scientists said they were worried about the death rate , the highest in almost two decades. Some of the mammals were underweight, which may mean they could not find enough food in the water, a possible result of climate change, NOAA spokesman Michael Milstein said.

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