The current theory surrounding the extinction of Hydrodamalis gigas (Steller's Sea Cow) is that is was not directly caused by hunting of that animal.
Unlike manatees and dugongs, sea cows fed on kelp, common cold water algae in the north pacific. Sea urchins are extremely efficient at feeding on kelp as well. Sea otters more or less keep sea urchin populations down, as sea urchins and other hard shelled invertebrates comprise the majority of their diet. Decline in the California Sea Otter has been linked with steady decline in kelp forests along the CA coastline.
Sea otters were evidently a very important resource for natives, and have been depleted from their original range, starting with the first humans migrating into north america. So, the decline in sea cows was probably caused by harvest of sea otters by native americans/asians in prehistory. So, when Steller (Not Bering) discovered these things, they only inhabited shallow water around two small islands. They were definitely long on their way out when they were discovered.
Unlike manatees and dugongs, sea cows fed on kelp, common cold water algae in the north pacific. Sea urchins are extremely efficient at feeding on kelp as well. Sea otters more or less keep sea urchin populations down, as sea urchins and other hard shelled invertebrates comprise the majority of their diet. Decline in the California Sea Otter has been linked with steady decline in kelp forests along the CA coastline.
Sea otters were evidently a very important resource for natives, and have been depleted from their original range, starting with the first humans migrating into north america. So, the decline in sea cows was probably caused by harvest of sea otters by native americans/asians in prehistory. So, when Steller (Not Bering) discovered these things, they only inhabited shallow water around two small islands. They were definitely long on their way out when they were discovered.