Place a stone foundation with doorframes around it and a ramp leading to the inside. Open a giant beaver damn and the chase will begin, just go inside the trap and when the castoroide goes up the ramp and falls in the trap exit it and shoot trank arrows at it. If you are taming with mejoberries like I did you will need a lot of narcotics because these thing loose torpor like there is no tomorrow. Once it is tamed demolish the trap and you’ve got yourself one of the best wood harvesters in the game