Re: nontrapper ?
Glad your dog is OK and you knew how to release him.
Like LF stated, ID number or name and address. They went to the optional ID to avoid retaliation and confrontation. If you NEED to know the owner then the PGC is brought into the middle. The extreme anti groups on their sites will publicly publish names, addresses, work addresses, and photos of individual trappers if they can get them. So the ID number provides legal anonymity.
If there are no labels at all I would report it. He is probably trespassing and doesn't want to be identified.
Stand up and be counted, join an outdoor sports organization
Life NRA,Life PTA,Annual SCI