do northern and southern populations of blue, right or humpback whale ever mix?

Question

Obviously, they did at some point, could science show us when this last happened?

Answer 1

Northern and southern Humpback communities don't seem to intermix; they have different markings, different songs, and never seem to meet.

Northern and southern right whales are actually different species, so not only do they never meet, they couldn't interbreed if they did.

Even communities of the same species that do share territory seem to remain separate; the Orcas around Vancouver Island, Canada divide into "locals" who mainly eat salmon, and "pelagics", visitors from the open Pacific that come in after seals and sea-lions. Locals drive off the Pelagics if they meet them. Apparently DNA evidence suggests no interbreeding between the two groups for at least 10,000 years.

Some recent DNA work even indicates that a lot of the whales we have been calling a single species (including Orcas and Humpbacks) are arguably not.

Answer 2

since whales like any other mammals need to avoid inbreeding I suspect that there is a movement of members between groups. they don't stay in the arctic and the antarctic all the year round and certain times they move to equatorial waters and no doubt meet then

Answer 3

they may occupy the same territories but keep to them selves