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15.08.2025

Article in zek HYDRO International: Bringing Back Migratory Fish

It’s March 2024 and dangling precariously over the Santee River in the United States is the next big global innovation in highly efficient fish passages. The waters below are rising fast… a flood is coming. Hanging from the hook of the crane is 1.3 million USD of funding from the U.S Department of Energy (DOE) in the form of the flagship product of Fishheart Ltd., its
state-of-the-art hydraulic Fishheart unit.

Some 7500 km away, in Finland, the phone is
ringing and Fishheart’s management is dealing with the situation.
Not all pilot projects have as dramatic a story as Fishheart’s latest test in South Carolina, but
to understand how it all came to this point, we need to start at the beginning.

In 2016, Tarmo
Aittaniemi, innovator of Fishheart’s patented system came together with fellow fishermen
Mika Sohlberg and Magnus Breitenstein with a common goal in mind; to restore fish
populations to their built rivers while providing the technology and knowhow to do so from
three lifetimes worth of fishing.
The first Fishheart unit entered the waters of Finland during the summers of 2017 and 2018
at the Merikoski Power Station, Oulu, and Isohaara Power Station, Kemi. Since then, their
success has gained them traction in the Nordics where they permanently operate over four
different sites.


Fishheart Ltd takes its name from its unique design; based, like a heart, on chambers and
valves. Unlike most fish passages, Fishheart is a completely adjustable system which
eliminates the chance of miscalculation in positioning the entry to the fishway, allowing the
team behind Fishheart to continuously monitor and improve the performance of its fishways.

 

A closer look at the construction

A fully functioning system is made up of a pipeline, a floating unit in the form of a pontoon, a
control container with electrical system hardware and monitoring units. The floating unit is
strategically placed below the dam wall and attached to the shore using adjustable wire
ropes.
Once fish enter the area, they are attracted by the outer attraction flow coming from the
floating Fishheart unit. The outer attraction flow acts as a beacon for the fish who then
become attracted by the inner attraction flows under the water. The inner attraction flows
lead the migratory fish into one of two chambers.

Once inside the chamber, Fishheart’s AI
based recognition system identifies the fish, its species, the number of fish inside the
chamber, their size, and relays that information to an external or local server before
approving or denying the system to open the fishway. The whole process is automated and
controlled remotely using preset preferences dependent on the location and takes place in a
split second.


Once the fish has been approved, the system starts a series of functions and the fish travels
over the dam wall through adjustable piping aided by the siphon effect with water used from
the upper basin. This makes Fishheart a closed system with fish being protected by water
the entire time and all water used in the process returning to the upper basin for use in
power production. Invasive species will be taken away from the aquatic system through a
separate pipeline.


 

Successful US test with a bonus

At the end of September 2023, in a bid to tackle the biodiversity crisis that continues to be
globally tied to the move towards clean, renewable energy sources, the DOE announced its
allocation of funding for six fish passage research projects. Fishheart, together with
monitoring body Electric Power Research Institute (EPRI), was allocated the largest funding
of 1.3 million USD to evaluate their ability to provide safe, timely, and effective passage of
American Shad at the Santee Spillway hydropower project in Pineville, South Carolina.

The test ran from 28.2–2.4. and was halted between 7-19.4 due to a need of spilling water
through the Santee River, which raised the water level by 8 meters.
The results published by Alden Research Laboratory (ARL) exceeded the expectations of all
parties involved. Over the course of 12 test days after the flooding, the Fishheart unit was
able to safely move 3410 fish into a fish tank for monitoring. Of these 3410 fish, 15 different
species were noted with a critical point being that using its attraction flow and underwater
guiding system, the Fishheart fishway was able to provide safe passage to fish swimming at
all levels under the water.

The unit safely moved 1193 Gizzard Shad and close to 1000 Blue
Catfish, both known for their bottom dwelling behavior. In addition, 1241 fish used the
Fishheart during the first week of the test before the flooding started, so in total 4651 fish
used the fishway during the duration of the test, of which 361 were American Shad. The
well-being of fish was monitored by ARL in separate evaluation tanks and fish were in good
condition.


And what about that phone ringing back in Finland? Well, the unforeseen flooding gave
Fishheart Ltd an unexpected but positive bonus result for their longevity in the fish migration
industry. Once the alarms had been set off and the spillway was soon to be put under
extreme pressure, it took only 4 hours to get the Fishheart unit out of the water. The unit was
safely moved away from the path of destruction and reinstalled in a similar time frame. There
was no need to clear out mud or debris, no need to check the calibration of the velocity of
the attraction flow coming from pool entries or any other fuss that may have arisen in the
same situation with a traditional fish passage.


Following their success in the US, Fishheart is now setting their sights on the central
European markets of Germany, Austria, Switzerland, and France, providing an affordable
solution to the growing pressure on EU countries to fulfil their commitment to the restoration
of their river systems in the coming years. Alongside this they are launching a pilot project in
Australia later this year.


 

Interested in learning more about Fishheart?
Please reach out to our sales representatives:


Mika Sohlberg
Sales Director

+358 500 103 344

mika@fishheart.com


Matthew Nimmo
Sales DACH

+49 195 758 919 326

matt@fishheart.com

 

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