It says one wild coho AND up to two adults. The "and" makes the coho additive to the adults. If they wanted to say that the overall limit was only two adults then you say "only two of which can be adults and only one of the adults can be a wild coho."

It may not be what they meant but it is what they wrote. It isn't that hard to write regs clearly and part of the process of writing them should include how can this be mis-interpreted.