The known history of Steller's sea cow is well known, tragic, and short. In 1741, naturalist Georg Wilhelm Steller was shipwrecked on Bering Island. This is one of the Komandorski Islands, which lie between Kamchatka and the Aleutians. There he and his companions met the sea cow. It was a huge plant-eating mammal, up to 35 feet long, with a bilobed tail like a whale's and a placid disposition that made it easy to approach (and to harpoon). After Steller's crew finally returned to civilization, sealers and other voyagers began stopping off in the sea cow's haunts to slaughter the inoffensive mammals for their meat. By 1768, the species had apparently been hunted to extinction.
There are a few odd data bits about the sea cow that hint-just hint - it hung on a little longer. Native hunters reported killing them as late as 1780. Early Russian colonizers of Bering Island reported sighting sea cows in the 1830s. Fifty years later, the explorer Nordenskiold returned from the region with a sea cow skeleton of unknown age and a tale of a live sighting from 1854. In 1910, fishermen in Russia's Gulf of Anadyr reported a sea cow stranded on the beach, but the report was never investigated. Other Russian sightings in 1962 and 1977 came to nought.
Now we have some science indicating that the animal's range was, in fact, greater than we thought - although, alas, they don't hint at survival but at an earlier extirpation event. It extended, not west or south as sometimes suggested, but north to Alaska's St. Lawrence Island. Bones collected from the island were spotted at a handicrafts show in faraway Atlanta, Georgia (USA), having been made into knife handles, and the provenance traced to St. Lawrence. They were analyzed by the team of Lorelei D. Crerar , Andrew P. Crerar , Daryl P. Domning , and E. C. M. Parsons. (They also offer some older history I was unaware of: that "According to the fossil record, animals in the genus Hydrodamalis inhabited coastal waterways from Japan through the Aleutian Island chain to Baja California during the Late Miocene, Pliocene, and Pleistocene. Hydrodamalis gigas was still present in the Aleutian Islands and central California less than 20 000 years ago." )
The St. Lawrence population was apparently wiped out or driven out by Yup'ik hunters around 900 AD. So it is that one of the most fascinating animals in modern history met its fate as the hands of hungry humans: not once, but twice.
Haley, Delphine. 1978. "The Saga of Steller's Sea Cow," Natural History, November.
Mackal, Roy. 1980. Searching for Hidden Animals. New York: Doubleday.
Stejneger, Leonhard. 1936. Georg Wilhelm Steller. Cambridge, MA: Harvard Press.