EUREKA — Researchers have been unable to determine what caused the deaths of two gray whales that have washed onto beaches in Humboldt and Marin counties in the past week.

The Times-Standard of Eureka reports ( that Humboldt State University professor Dawn Goley was called to Manila Beach on Saturday evening on a report of a stranded whale. Goley tells the newspaper the 30-foot long whale had scars indicating it may have been caught in fishing gear, but it was too decomposed to know for certain.

She estimated its age at around 1.

Decomposition also prevented researchers on Friday from determining what led to the death of another gray whale that washed ashore on Dillon Beach in Marin County. Marine Mammal Center spokesman Jim Oswald tells the Marin Independent Journal ( the researchers did collect bones that will be used for future study.