Connecticut has a lot of dams. In fact, the state has one of the highest densities of dams in the country, which makes it difficult for migrating fish.
Dams are widely required to have a fish ladder or passage — traditionally, steel or concrete structures that allow fish to swim around obstacles. The problem?
“If they’re built in the wrong position in the river, and they’re usually fixed to a specific location because they are fixed infrastructure, a lot of times they don’t work at attracting fish into them," said Nikolas Hansen with Fishheart. That is the company behind the Hydraulic Fishway.
It is in the second year of a three-year pilot program at a hydropower station in Preston, Connecticut, operated by FirstLight. This is their first setup in North America.
“It’s a mobile and adjustable design, and it’s meant to be floating. So, we can position it anywhere in the tail race below the dam to most effectively attract the fish into the system.”
It is a long system of tubes that resembles a waterslide, starting at the top of the dam and cascading down.
“Once they swim inside the pipelines, our cameras will detect that there’s fish there, and it will close the entrance valves, so now they’re closed inside the pipe," Hansen said. "And then our AI is taking pictures, videos, identifying the species and measuring their length."
The built-in artificial intelligence also tells the system to speed up and push the fish through. Hansen said about 800 fish have passed through the system so far this season.
Another problem with traditional fish passages is the cost, according to Claire Belanger, communications director at FirstLight. The Fishheart system costs roughly 20% to 30% of the traditional structures.
"Hydro is a cost-intensive industry in terms of maintaining and operating dam infrastructure," Belanger said. "Anything that gives us adaptability to meet requirements and support fish passage and aquatic habitat, while addressing some of the cost burdens...it's really significant for the industry."
The goal now is for regulators to approve it.
"Generally, fish passage is very tailored and specific to each facility. It's not a one-size-fits-all," she said. "If it's accepted by the necessary folks, it's something we'll consider where we need to build fish passage across our portfolio."
Connecticut is home to more than 75 species of freshwater fish. The Hydraulic Fishway targets American shad and river herring at this location, whose populations are far below their historic levels due to habitat loss.
Hansen said improved movement of these fish is important for the health of the ecosystem.
"The whole food chain is affected. Obviously, predators eat these fish, they create a biomass in the river, and they act as bait fish for other fish," he said. "It's important that we return them to successful populations.
