What you need to tame them is like 6 or 7 tranq arrows, and like 30 meat. Go on a rock so they can’t reach you and then tranq them, once they are knocked out give them the meat, they take a while to tame so be patient and you might want to have 2 or 3 narcotics near just in case. Once they are tamed you can craft a saddle for them at level 35, they go super fast in the water and when you ride them around, you can kill a lot of stuff and get lots of meat and hides.