I usually use my high level starco (lv 130) to clear out the area then I knock it out from the shallows. They long agro range some careful to remember which one is high level... I'm actually typing this right after I knocked out lv 108!
I was taming one of these bad boys in the herbie island pool and when i finally got it to torpor run it beached itself but still lived if you know what i mean. Ark logic? Anyways it stopped moving and i figured it was just stuck. make sure to check your taming tracker. Thats why i had a lvl 67 shark instead of 89.(i was new to the game ok?) This was in ASE not ASA.