Trapping- it's a 3 for 1 trap. Trap will work for plesio, moss, Squid. 4 sides of behemoth gates. 4 corner inside trap with pillars higher than gate. 3 Celling on each pillars going center of trap. So only a small gap in center. Now take a small angler or ichy or shark. Lure dinos in and get out from top and close door.

Voilà.

Early game taming trap for big water dino. Now your problem is getting it tamed after that. They take a lot of ressources to tame.

I would suggest plesio and kill other stuff with it like alpha to get black pearls and Lure squid in same trap.