For SE hope one spawns near the beginning of the blue cave getting one out is really hard and most likely have to be done during the night since if heir sleep meter is too high they will drown because they won't swim to the surface.
Use the L2 to pick up small dinos in its mouth, then bring them to the destination of your choice, and have a friend tranq the small dino while in its mouth to knock it out. I use for taming ravagers, kill low levels then pick up alpha and bring to your base to knock out and tame. Works wonderfully!
What you want to do is set it to stay awake in the day it will build up torpor and get knocked whiles it's knocked out it will eat much less food as a baby but after it wakes up from torpor you have to set it back to stay awake