I just noticed something weird and was wondering whether anyone could verify/falsify this:
Currently trying to level cooking on my alt with minimal invest, which means by fishing. Therefore going after the Man O' Wars. I started in the Borean Tundra, eastern-most point of the coastline and worked my way along, finding almost no schools.
When I'd reached the ruins in the south, I frustrated started fishing out the Manta Ray schools, in the hope of causing Man O'War schools to spawn. There was not a single such school until I reached the northern-most point of the coastline.
I then cut across the tundra and started in the east again and when I passed the ruins, Man O'War schools started showing up. Every single fish school up to the northern-most point was a Man O'War school, no Manta Rays in sight.
Is it possible that the schools there flip between Man O'War and Manta Ray every time they respawn?