Just down the street about two miles from my parents' camp on the shores of Lake Merrymeeting is the Powder Mill Fish Hatchery, managed by New Hampshire Fish and Game since the 1940s. It's a substantial operation; nearly 300,000 fish a year are released from the hatchery to New Hampshire waterways. No hatchery in the state produces more.
Granite State fishing enthusiasts (of whom - unlike my brother and father - I am not one) will tell you that only the brook trout is native to the state - rainbow trout are from California and brown trout from Germany. There are no native freshwater salmon in New Hampshire at all, only those spawned at Powder Mill, landlocked cousins to the saltwater Atlantic salmon. So if you work with the rod and the reel, be thankful for the gang at the hatchery.
It's a neat place, whether you're an angler or not. The concrete raceways contain hundreds of thousands of fish, protected from airborne predators like herons and eagles by broad swaths of netting. The kids always enjoy a trip to the hatchery on a summer day, putting a quarter in the machine to get a cupful of pellet fish food to toss to the swarming schools. You can tour the operation too, seeing the racks of incubating eggs and learning more about the process.
I'm glad the kids like it, and I'm perfectly happy for New Hampshire's rivers and lakes to have an abundant supply of fish to keep reeling in tourists. As for me, I love that the sight of the hatchery means I'm just minutes from another visit to the lake.