The IoT Fish Counter
A low-cost, low-maintenance IoT device that automatically counts and sizes fish in trap-net fisheries — designed and built end-to-end.
Commercial fishing is tough, and margins are thin
Finland has roughly 700 registered commercial fishermen working in harsh conditions with slim profitability. To check their catch, coastal trap-net fishermen typically motor out to their nets every single day — burning fuel and time whether or not the catch is worth collecting.
Developed in collaboration with the Natural Resources Institute Finland (Luke) and fisherman Mikael Lindholm of Söderby Lax, the Fish Counter answers a simple question: what if you could know exactly what is in your net before leaving the harbour?
What fishermen actually care about
- Low-cost device that pays for itself
- Minimal upkeep and service in the field
- Indicative fish size — salmon, whitefish and more
- A custom, genuinely easy-to-use mobile app
How the Fish Counter works
A camera gate mounted in the trap-net's fish chamber captures every fish that swims through. On-device computer vision counts each fish, estimates its size, and pushes the data to the cloud — all powered by solar in a fully marine environment.
Capture at the gate
Fish swim from the net's funnel into the fish chamber, passing through an imaging gate that photographs each one in the water.
Count & size on the edge
Embedded computer vision detects, counts and estimates the size of each fish, distinguishing valuable species like salmon and whitefish.
Sync to the app
Counts, size distribution and a real photo of the catch are sent over the network to an AWS backend and a purpose-built mobile app.
Built end-to-end, single-handedly
This project spans nearly every engineering discipline — and I owned all of it: from the first sketch to a device deployed in the Baltic Sea.
Real-time catch data in your pocket
The companion app was designed for fishermen, not engineers. Field-trial users reported genuine excitement opening the app to see a live photo of their catch and its size distribution before ever leaving the harbour.
- Intuitive interface built around the fisherman's workflow
- Simple diagnostics data to keep the device healthy
- A real image of fish passing the gate
- Fish count and size-range distribution at a glance
Less fuel, less carbon, better catch
By letting fishermen decide when it is worth heading out, the Fish Counter cuts unnecessary trips.
That is roughly 390 litres of gasoline saved per fisherman each season.
Equivalent to about 0.9 tonnes of CO₂ emissions avoided per fisherman, per season.
On stage and in the spotlight
Presidential state visit
Presented the Fish Counter to the Presidents of Finland and Iceland during the 2025 Icelandic state visit at Aalto University Design Factory.
EU Commissioner
EU Commissioner Costas Kadis was impressed by the innovation during a 2025 visit to Loviisa, hosted with fisherman Mikael Lindholm.
Industry conferences
Featured across Finnish fisheries events including Kalatalouden Innovaatiopäivät (2021, 2024) and Ammattikalastajaristeily (2025, 2026).
Coverage & publications
Independent presentations and publications about the Fish Counter project.
- Ammattikalastajaristeily 2025 — Esa Lehtonen (Luke)
- Kalatalouden Innovaatiopäivät 2021 — presentation (PDF)
- Kalatalouden Innovaatiopäivät 2021 — video recording
- Kalatalouden Innovaatiopäivät 2024 — Albin Weckström, IoT-kalalaskuri (PDF)
- Maaseutuverkosto — funding for hybrid vessel & fish counter
- Ammattikalastajaristeily 2026 — Esa Lehtonen (Luke)
Have a hard problem in the water?
From marine IoT to end-to-end product development, I take ownership from ambiguity to a working device.