Why do dead whales keep washing up in San Francisco?

A recent spate of deaths in the region has caused concern, but scientists say it may not be a sign of catastrophe

The 45ft carcass lay belly-up in the surf at Fort Funston beach, just south of San Francisco, drawing a small crowd of hikers and hang gliders. The stench lingered on the evening breeze as seabirds circled the animal, a juvenile fin whale.

The whale was the fifth to wash ashore in the area this month. The other four were gray whales - giant cetaceans who migrate an astounding 11,000 miles each year from Alaska to Baja and back - all found on beaches near the city over a span of just eight days.