I didn't understand the Homer fishing hole until I was there recently. It made no sense that a little tidal bay would attract salmon. But in this case, the salmon are raised to fingerlings there in the hole. So they return to the hole in their return to spawn. It's never going to happen, so they return to be caught and eaten (aside for a steady selection of a few for collection of eggs for the next crop).
The rush of fish and water when the incoming tide crosses the bar is quite a sight to see. From the perspective of world fish farming this is just one more farm. But it is an interesting way to harvest the open ocean.