Humphrey is a member of the species Megaptera novaeangliae. Each episode of his bay incursions resulted in a dramatic estuarine rescue by the Marine Mammal Center, based in Marin County, California, assisted by the United States Coast Guard and hundreds of other volunteers. Humphrey (sometimes known in the media as Humphrey the humpback whale) was 40 feet (12 m) long. The last sighting of Humphrey was in the vicinity of the Farallon Islands in 1991.