there's a difference between "targeting" and "accidentally catching".
There's a rule in NH on the big lake regarding salmon during ice season.
You might hook one while targeting other trout species, but shouldn't remove them from the water but release ASAP.
Of course here in MA the only real restrictions regarding what we can catch and keep relate to specific species seasons and size/creel limits, and that's only if you willingly adhere to the rules.
What surprises me is that with no open season and no keep rule, why haven't they had a growth in population?
Then again, the same could've been said about the failed Atlantic Salmon fishery as well...