Otters only spawn in one location in the southwest portion of the map on the Lost Island of Ark Survival Evolved.
I found the otter in the video at:
This swampy location is not only where otters are found, but sarcos, kapros and other nasty creatures, so come well prepared to tame them. It is always a good idea to bring a scuba tank, and flippers.
|Ark Lost Island Otter Location Map|
|Lost Island Otter|