Triggerfish in NH?

I was browsing the NH fish and game records and found mention of a triggerfish caught last year in the Piscataqua. http://www.wildlife....rophy/2012.html I found a bit more info on it here http://www.gofishn.c...e/its-official/ but not much.

Wait a minute, a TRIGGERFISH in New Hampshire? Aren't those tropical reef fish? I know southern New England gets tropicals as it is near the gulf stream, but I assumed anything further north was too cold.

Does this mean their is a cold water triggerfish species? Or did one stray get blown way off course and somehow survived in the colder northern waters.

(the river it was caught in also confuses me as it is saltwater for quite a ways up, and I wonder why the force of a rivers flow does not wash out the salt. This is one of the two geologic puzzled i have found since going on trips to find fish, but never asked as it seems off topic).

There are temperarate Triggers, but tropicals often come up on the Gulf Stream. A few years back I went out on a boat out of Wildwood NJ and the crew was still talking about the 16" Queen Trigger somebody had caught the previous day.