I didn't saw anyone saying thing but if you go near one with a boat and just stay still they actually come and land on one of the edges of the boat. After that just bola him and shoot so you can tame him safely on the boat. Bring alot of narcs because torpor does come down quite fast and it takes alot of time for him to eat.
They do only way fish meat, but they seem to be fine on normal meat if it's in a trough? I was going mad trying to keep them topped up with fish till I noticed their health/hunger wasn't going down when it ran out of fish but still had raw meat in it.