The First Marine Mammal Driven To Extinction By Humans Disappeared Only 27 Years After Being Discovered

The gentle giants that are the sea cows – meaning manatees and dugongs – are some of the most iconic animals out there, but they’ve also become vulnerable to extinction through the actions of humans – and it’s not even the first time this has happened.

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Today, there are four living species of sea cows (also known as sirenians), but back in the 18th century another could be found off the coast of Russia’s Kamchatka Peninsula, roaming the waters around the Commander Islands in the Bering Sea: Steller’s sea cow (Hydrodamalis gigas).

Most closely related to dugongs, it was discovered in 1741 by biologist Georg Wilhelm Steller, after the expedition to North America that he was part of became stranded on Bering Island. Little did he know at the time that he would end up being the only scientist to see the creature named after him alive.

Steller’s sea cow is thought to have been much larger than the manatees and dugongs of today, estimated to have reached up to 9 meters (29.5 feet) in length and weighing up to 10 tons, with a layer of blubber almost 23 centimeters (9 inches) thick in some places.

In his copious notes on the species – having been stuck on Bering Island for 10 months with what we imagine was very little to do – Steller said there were so many of these large animals on just this one island “that they would suffice to support all the inhabitants of Kamchatka”.

Only now do we understand that there were really not that many Steller’s sea cows at this time at all, and there were several other factors working against them too: they only ate kelp, which limited their range to shallow waters; they were slow-moving and couldn’t fully submerge underwater; and they seemed unafraid of humans. Some research suggests that they probably were going to go extinct at some point anyway, long before they encountered humans.

But in the end, it was still humans who dealt the final blow, when fur traders in the Bering Sea began ruthlessly hunting Steller’s sea cows for food – their meat and blubber were both delicious, according to Steller – and killing the sea otters that maintained the kelp forests the sirenians relied upon.

As a result of this persistent predation, it’s thought that the Steller’s sea cow had gone extinct by 1768, a mere 27 years after it was first discovered. That’s notable in and of itself, but importantly, this also marked the first known time that humanity had driven a marine mammal to extinction.

Luckily, today we’ve got a much better awareness of the plight faced by the remaining species of sea cows, with concerted efforts to save them from the same fate as their relative. And when those efforts succeed – well, it’s quite the sight to behold.