Trapline info?

[Scheff27]

I am looking for a registered trapline and am wondering the best way of getting contact info for current line owners. I have found the Fish and Wildlife Internet Mapping tool and have figured out how to use it and it does give some of the names and contacts of current owners but probably about 1/3 of the lines in the general area I am looking, has no info or contacts about who owns them. Is there a reason why some have it and others don't? How would you go about finding contacts for the lines with no info posted?

Thanks