Is a 4-coiled #2 square jaw big enough for otter?

Set for otter using a drowning rig or coni. I have held otter with traps as small as a #1 longspring, but in that case, the trap was attatched to a plywood mink box with double 14 wire. The whole mess got tangled up in an alder thicker, giving the trap a spring when the otter pulled. There weren't many alder sprigs left when I came along, and the otter was totally exhausted.
In short, your trap would work fine. But I wouldn't just wire it to a tree. Otter roll and spin like crazy when caught. Use a drowner.

This right here. That trap will work fine. But like AV mention they are powerful critter. Anchor them good.

OK, thanks guys! I'll use it in a submersion set

I use my Duke 1 3/4 or #2's. They hold them just fine. Plus it cleans them up from catching fox and coyotes. But definitely run them on a drowning cable with enough weight. You don't want one pulling your drowning weight up on shore and him waiting for you and now your area will Looks like a bomb went off.

The first otter I caught was in a Duke 1.5 CS set for coon in a water set anchored with rebar. "A bomb went off" is an apt description of what I saw. He was none too happy with me which made for an interesting release (at that time otter were permit only and I didn't have one).

A four coil is a lot of trap for a otter, especially when it is paired with a square jaw. I like round jaw traps with a shallow depth from top of the jaws to the top of the pan. Otters have very small front legs and if you catch them too high they can pull out. They are extremely strong but remember their front legs are very small in comparison to their body. I like using a strong 1 1/2 or 2 CS or a #11 DLS. I make sure my springs are strong, the base is strong and I put a couple of swivels in the chain. I catch a lot of otters on dry land sets and I use a earth anchor, and it holds. Drowning isn't necessary if you anchor accordingly. And, if you have a live market for them you will loose out on a LOT of money killing them. If I'm in soggy bottoms I run a cable around a tree, and then swivel mount another cable going to my trap. I also use drowning cables on dry land to get the otter off the trail as if they trail gets messed up, the others in the bevy will make a new trail going around the disturbance.

Body grips I use 280's for where they come out of the water on crossovers and I use 220's in established trails. I only use 330's when I run out of 220/280's as a 330 will suitcase them and sometimes they are halfway through the trap before it fires.

I might have 10 to 15 otters in a day and I would say 1/3 of them are still alive in the traps with no issues, as they are anchored solidly. I prefer them dead, but you have to set to the ground you're trapping. If I have a live market for them I will nothing but #11 DLS.

If you are in the Louisiana area this Saturday I will being giving a demo at the Louisiana Trappers and Alligator Hunters Association Fall Convention on dry land and water sets for otters.

only caught 4 otters not on purpose. one in a 330 slide set for beaver and 3 in pocket sets for coon with a duke 1.5 double jaw with an 18in pogo anchor, held them just fine. we can take 3 er year here. if youre anchored good then a 1.5 is enough. the 3 i caught werent going anywhere. one of them ruined a brand new pair of hip waders cause i forgot how long the chain was and he bit right through them thankfully only the wadder and not my thigh. they are vicious animals for sure. ive had coon come at me when in a trap but not like that otter did. he was crazy lol.

im not saying the 1.5 is the best trap but they will hold them.