Smart Signal crayfish trap

RAKOŽER Smart Signal crayfish trap

Signal crayfish (Pacifastacus leniusculus) came to Slovenia from Austria (where they were grown) shortly after year 2000 at the time of the floods. The signal crayfish is now considered an invasive species across Europe, Japan, and California ousting native species there a causes a lot of damage. It is resistant to duck plague and is therefore an effective carrier. It is a strong competitor to native species as it feeds on everything it finds including native crayfish. The signal crayfish does not harm only to the native crayfish, but it also displaces many other aquatic organisms like fish, amphibians, invertebrates and algae.

Signal crayfish is a smaller crayfish, with robust scissors growing up to 16 cm in height. The entire surface of the crayfish including the scissors is apparently smooth, which reliably separates it from the native one. It inhabits rivers, lakes and brackish waters by the sea. It is insensitive to water temperature, oxygen concentration and elevated salinity. We must be aware that colonization of invasive crayfish cannot be avoided, but we can slow it down and limit it. Because crayfish has no natural enemies, there is only one solution, to hunt it. Hunting is easiest with a fish trap, that can be made from shopping baskets. Trapped crayfish can be used for food because they are very tasty and so at the same time we address UNESCO’s Global Goal no. 2 Zero hunger.


We designed a smart crayfish trap. The trap will be mounted on a stick or a bracket attached to the bank of the river, or to a boom where no slope mounting is possible. Our custom made Micro:bit water height sensor is attached. When crayfish catch into the trap, it falls down towards the bottom of because of the weight. Each change is detected by our sensor and the Micro:bit then sends the data via Bluetooth to neighbor traps and then to fishing inspector. Crayfish do not swim, of course, so our innovative solution is a net that connects across the top and reaches the bottom of the river. This gives the crayfish a chance to climb on top and into the trap where the bait is. As the level of the Drava River changes, an additional sensor that measures the water level is required for calibration.

Crayfish is less active in winter and so they are difficult to catch, so we will test the trap in summer.


When the water reaches pin1, pin2, or pin3, contact is made, electricity goes off and water level is reported to the via Micro:bit.

Only girls are involved in the project, thus also addressing the 5th Unesco Global Goal for Gender Equality. Being girls ourselves increases the share of girls in STEAM. ? Entering the competition is part of the larger story of the project. Tina Cigler, Barbara Planinšič and Urška Krajnc also participated in the implementation. Fisheries inspector Slavko Prijatelj answered some of our questions. Thank you all!

Kako deluje program?

Korak 1

Vstavimo blokec ˝on start˝, dodamo ikono in določimo skupino Micro:bitom z ˝radio set group˝.

Korak 2

V zanko forever vstavimo ˝serial write line˝, da nam bo odčitaval pine v vodi.

Korak 3

Vstavimo if zanko. Nastavimo pin P0 > 300, potem bo prikazano število 1 in radio bo to število poslal na drug Micro:bit.

Korak 4

Enako naredimo še za P1, P2 in P3.

Korak 5

Na koncu dodamo še ˝show number  0˝ in ˝radio send number 0˝, če je kletka prazna.