Lox? Never seen a yak in game...

I don't think they have dedicated spawns. In most of the smaller sections I have made farms in they are just one of several things that have an RNG chance to spawn. If another thing spawns there all you need to do is kill them to clear the area again for fresh things to respawn.

In larger plains areas you can have multiple groups spawn at the same time, that makes it nice to fill up a box of lox.