You can live cage trap them like a coon on the dock @ kit Carson
I haven't been trapping for very long but..
For the on the land sets (almost always on a dock)...
I've had the most success in the large Havahart traps (very strong, they're not chewin thru those).
Wired a can of sardines up high behind the pan (ideally behind some coni triggers if it's a modified cage).
I like to make a little "cup" out of tinfoil and then pour the sardine juices in there...also use clam juice. Put that cup in the bottom of the trap behind the pan.
Wire some big shiny fishing flashers up in the top-back of the trap next to ur shiny can full of sardines. I always dribble a little of the juices from the front of the trap all the way to the back to lead them in with scent/flavor.
A few drops of Cavens Otter Lure "Supreme" and/or Lenon's Otter "super all call lure" into the tin foil cup works nicely too.
I had an opportunity to put several traps and trail cams in a large boat house and test baits and lures on several different otter families. That's what worked the best for me. I could really tell what they liked and didn't like with multiple video cams on the traps but I think every area is different and everyone has their own style. Good luck this year man!