Recently we were in Newport, Oregon. Upon stepping out of the car near the coast, there was the sound of a lot of sea lions, barking and calling to one another. We walked out on the dock and saw sea lions on platforms, on rocks, and swimming all over the place. A metal cage was present, which researchers can close and then tag some of the sea lions for study - the cage was filled with sea lions when the door was open.
Although there was clearly quite a collection of these animals, and a few signs giving some information about them, there was no explanation of why they gather in this particular location in October. It's always nice to see marine mammals, regardless of why they are there - and this viewing we had Maisey and a guest dog with us. The dogs were unimpressed by the incessant sea lion barking.