A federally endangered fin whale washed up dead on a West Marin beach after apparently being struck by a ship, officials said Monday.

The 47-foot-long whale was first spotted Thursday in a remote area south of Wildcat Beach in the Point Reyes National Seashore. Biologists attempted to try to identify the animal, but heavy surf and the whale's position made it too difficult.

The team returned Friday and was able to identify it as a juvenile male fin whale. The team concluded the whale had been killed after being hit by a ship. Injuries to the spine, ribs and other skeletal elements and tissues were extensive.

"This is another dramatic example of negative human impact on marine mammals," said Dr. Frances Gulland, senior scientist at the Marine Mammal Center in the Marin Headlands. "The spine of this whale was completely fractured as a result of a ship strike and it is very sad that this animal's life came to an end in this manner."

Tissue samples have been taken from the animal for study, but there are no plans to salvage its bones. The tide is expected to take the carcass back out to sea.

"We will let nature take its course," said John Dell'Osso, spokesman for the seashore. The whale previously had been seen during a research trip by researchers from PRBO Conservation Science, as well by researchers from the National Oceanic and Atmospheric Administration's Cordell Bank and Gulf of the Farallones National marine sanctuaries.

Fin whales are the second-largest mammal on Earth, behind the blue whale. Females average 61 feet; males are slightly smaller at an average 59 feet, but can attain lengths of nearly 90 feet.

They are the fastest of all large whales, reaching speeds of 25 mph. The fin whale is a filter-feeder, feeding on small schooling fish, squid and crustaceans, including krill. It forages along the continental shelf break and the outer continental shelf but may venture near shore at land promontories such as Point Reyes.

Fin whales are listed as endangered under the Endangered Species Act. They generally roam the world. Fin whales are divided into several populations worldwide and the population that occurs from Washington to California is estimated to be around 2,000 individuals, scientists say.

Several endangered whale species have been feeding off the north-central California coast in recent weeks, including blue, humpback and gray whales. The abundance of krillsmall shrimp-like crustaceanshas attracted them, and when focused on feeding, whales often do not take measures to avoid oncoming ships, according to scientists.