A Brief History of Fishladders

The fishladder at Amoskeag Falls. Note the small openings to attract the fish with stronger current. (Jon Greenberg, NHPR)

Most people think that fish ladders are a relatively modern invention. They aren’t.

I’m Sam Evans Brown with this Merrimack River Minute.

At the start of the 1800’s, herring, salmon and other fish filled the Merrimack every spring. Then came the dams. Wendy Schorr, a naturalist at the Amoskeag Fishways, says the dam builders knew they would block the fish headed upstream to spawn.

And so, in 1836, more than a century before the environmental movement, they tried to give the fish a chance.

[Cut] Schorr: When they first built the very first dam here at Amoskeag . It had a fish ladder on it. It didn’t work and eventually a flood took it out, but the idea was there.

Building a fish ladder that the fish will like is tricky. You need to attract them with a strong smooth current but if it’s too strong, the fish won’t be able to get past it. They’re also easily distracted by other currents which can take them away from the opening to the fish ladder.

With this Merrimack River Minute, I’m Sam Evans Brown.