ANCHORAGE, Alaska (AP) – Native hunters from Alaska will not be prosecuted after they used harpoons and guns last year to kill a protected gray whale that strayed into a river from the North Pacific Ocean.

The National Oceanic and Atmospheric Administration instead sent three letters advising villages about the limits to subsistence whaling, the agency said in a statement provided to The Associated Press. Federal law prohibits the killing of gray whales even though Alaska Natives are allowed to kill other whales.

The massive animal strayed into the Kuskokwim River near the Yup’ik village of Napaskiak and was killed on July 27, 2017, in a region where indigenous residents rely on subsistence fishing and hunting as part of their ancient culture and traditions.