The best area to tame is Ocean: SW. I found plenty of them swimming around, including the 150 male I have tamed. There is a trench that spawns the fish swarm, guide it to the giant turtle & YOU CAN WATCH FROM A DISTANCE! You do not need to be near the turtle for it to continue taming, bring a swimming tame that’s fast enough to guide Megalodon‘s to another turtle so you’re taming progress doesn’t reset when they bite you’re turtle. This took over an hour with taming 3x. Hope this helps!