The Extermination of the Stellar’s Sea Cow

The Steller’s Sea Cow was the largest member of the Manatee and Dugong family, reaching the incredible length of 30 feet and weighing over ten tons. It wasn’t discovered by science until 1741. And by 1768, in the space of less than 30 years, it had been utterly exterminated.


Steller’s Sea Cow. A contemporary engraving.

In the early 1700’s, the Tsar of Russia, Peter the Great, became interested in North America. The French and British colonies there were extracting an enormous wealth in furs, timber and other materials, and the Tsar wanted a piece of it. But eastern Russia was at this time largely unexplored, and the huge frozen wasteland in Siberia was so little-known that nobody was even sure if it was connected to North America: it was proposed that Siberia might actually have a land route into North America. In 1728, the Russian government appointed a ship stationed in the East Indies, under the command of Russian Navy commander Vitus Bering, to find out. Bering sailed north to Kamchatka and followed the coast all the way to the Arctic Circle. There was, he reported, no land bridge into North America.

In 1741, Bering proposed to the new Empress, Anna, that he should lead a second expedition to explore the area. Empress Anna granted him two ships, the St Peter and St Paul. They left Kamchatka in June. After a short time, however, a storm separated the two ships. The St Paul,commanded by Captain Vasiliy Chirikov, discovered a number of islands (now known as the Aleutians) before returning to Russia. In the St Peter, however, Bering reached the part of North America that is now known as Alaska, claiming it for the Empress.

But on the way back to Russia in November, disaster struck–the St Peter was heavily damaged in a storm, and the crew had to disembark on an unpopulated island near Kamchatka, which would become known as Bering Island. It took nine months for the crew to prepare timber on the island and repair the St Peter enough to make the trip home. During that time, their food ran out and they were forced to hunt the local wildlife. Starvation and scurvy killed most of them, including Captain Bering. Only a handful lived to return to Russia in August 1742.

One of the survivors, however, was Georg Steller, the ship’s naturalist. He had already obtained some specimens from Alaska, including a new species of sea lion later named Steller’s Sea Lion, a new species of duck named Steller’s Eider, and a jay named Steller’s Jay. (The jay was, Steller noted, similar to the American Blue Jay and indicated to him that the newly-discovered Alaska was in fact part of North America–it is the only species discovered by Steller that is not now either endangered or already extinct).

After the shipwreck, while the sailors worked to repair the boat, Steller took advantage of the forced stop to explore the wildlife on Bering Island and the surrounding waters, and discovered an additional number of new species, including Steller’s Sea Eagle and the now-extinct Spectacled Cormorant. But his most famous discovery became known as Steller’s Sea Cow.

The Sea Cow, given the scientific name Hydrodamalis gigas, was not a seal, but was a member of the Sirenid family, along with dugongs and manatees. Aside from the whales, it was the largest sea-going mammal, measuring up to 30 feet in length and weighing at least 10 tons–the size of a school bus. Like all of the Sirenids, it was entirely aquatic and could not leave the water. The front limbs consisted of short curved paddles, and the rear limbs formed a flukelike tail for swimming. The massive football-shaped body was protected from the cold water by a four-inch-thick layer of blubber, and the skin was thick and rough, looking something like tree bark.

Gathered together in small herds, the Sea Cows spent their time placidly paddling around in the shallow waters just offshore, grazing on the aquatic algae, kelp, and seaweeds that grew on the underwater rocks. Their portly bodies were apparently so buoyant that they could not dive, and this made them easy targets on the surface, but the shallow habitats that they preferred protected them from sharks or killer whales. They had no predators–until the humans showed up. The shipwrecked Russian sailors viewed them as a ready food source, and regularly sent out teams with spears, either in boats or just by wading out to them. The naive animals, with no experience with predators, made no attempts to escape, and the sailors killed a large number of them. Steller had the opportunity to study and dissect the animals closely, and took pages of detailed notes on their behavior. The Sea Cows seemed to form monogamous pairs, Steller noticed, which bore single calves in the fall.

When the shipwrecked crew of the St Peter finally managed to get back to Russia, they reported that the “Bering Sea” was full of valuable fur-bearing sea otters and seals, and also had a convenient source of food to resupply the ocean-sailing hunting vessels in the form of the Sea Cows off Bering Island.

Russian ships began scouring the area, as sealers, whalers and fur-hunters all sought their fortunes. The hunting ships often stayed out at sea for 2 or 3 years at a time, filling their holds with otter and seal pelts. When the seas filled up with ice, these ships overwintered on Bering Island, where they could stock up on the readily-available supply of meat offered by the huge Sea Cows. It was also found that the Sea Cow’s skin made an excellent leather, and that its fat could render up an oil that, like whale oil, burned cleanly and without smoke in the oil lamps that were common at the time.

Within ten years, the damage was being noticed. Populations of sea otters and seals dropped precariously (the Sea Otter is still listed today as an endangered species, and the fur seals are legally protected from hunting). The Sea Cow had become so rare that in 1755 the Russian Government issued a decree banning its hunting. But it was already too late. The last recorded Steller’s Sea Cow was killed off the shore of Bering Island in 1768. The species had gone from discovery to extinction in just 27 years.

Georg Steller, the only scientist to ever see a living Sea Cow, returned to St Petersburg in 1742 and then traveled to Siberia, where he spent the rest of his life collecting specimens. Unfortunately, most of his specimens never made it back to St Petersburg and he was never able to publish any scientific papers on them. His Journal, including his description of the Sea Cow, was not finally published until 1751, almost five years after his death.

In the years after 1768, occasional reports gave hope that a few Steller’s Sea Cows might have survived. Some Inuit natives on the Aleutian Islands reported to explorers that they had occasionally killed large seal-like animals as recently as the 1870’s. In 1910 a large animal thought to perhaps be a Sea Cow washed up dead onshore in Siberia, but it was never scientifically examined. In 1962 the crew of a Soviet whaling ship reported that they had seen a group of six Steller’s Sea Cows in the Bering Sea, and in 1977 another Russian fisherman reported a sighting. But none of these have ever been confirmed, and most biologists have concluded that they were mistaken reports of either small whales or of Elephant Seals that had strayed north.

Today, about 70 museums around the world have skeletal remains of Hydrodamalis gigas in their collections, ranging from single skulls to entire skeletons.

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Forgotten mysteries, oddities and unknown stories from history, nature and science.