Those sturgeon are just full of surprises:
Sturgeon take surprise route from Maine to Merrimack River - BostonHerald.com
Haverhill must be very attractive to sturgeon. Apparently sturgeon from Maine secretly migrate down to the Merrimack River. Not all the Merrimack River sturgeon are hatched in Haverhill. Who knew? Apparently not fisheries scientists up until now.
Hope Merry Mac (get it?), the Haverhill mascot sturgeon, welcomes the out of state fish.