BANDON, Ore. (AP) — An endangered species of whale that became stranded on a southern Oregon beach died over the weekend, officials said.

The 38-foot (12 meter) sei whale died Saturday evening after it was stranded on the sand by the tide, The Oregonian/OregonLive reported.

Marine mammal biologists say the sei whale was not yet mature. The species prefers to live in temperate waters in the mid-latitudes. Officials said a necropsy would be done to learn why the animal got stranded.

Oregon State University and Washington-based nonporofits World Vets and Sealife Response, Rehabilitation and Research were performing the necropsy.

Afterward, the carcass was to be buried on the beach.

Sei whales typically live far out from coastlines in deep ocean waters. They are found in the Atlantic, Indian and Pacific Oceans. In summer, they are commonly found in the Gulf of Maine, and on Georges Bank and Stellwagen Bank off the U.S. coast in the western North Atlantic.

However, the whales have unpredictable patterns of where they live.

The whales are endangered in the U.S. According to the National Oceanic and Atmospheric Administration, there are about 8,600 sei whales in the North Pacific — 20% of the 42,000 that used to live in those waters.