North Pacific right whale
The North Pacific right whale is in a similar position. In the eastern North Pacific there is a population of 30-35, while the western North Pacific is around 300.
It should be noted, that despite this numbers, the North Pacifi right whale is only considered Endangered. not critically endnagered.
While hunting was the initial driver to drop the population. Current threats include ship strikes, as well as entanglement in fishing gear, and of course the small size of the population. Some of the places with the highest density are Bering Sea, Gulf of Alaska, Okhotsk Sea, Kuril Islands, and Kamchatka area, though I should mention that this is a huge area, so does not help a great deal.