Sensorfisch: Pocket-Sized Species Conservation

  Sensor fish in a trial tank Copyright: © Elena Klopries

Despite "green" technologies' increasing importance for energy production in the 21st century, they often also attract the attention of nature conservationists. A well-known example is windmills, which can have fatal effects on red kites and bats. Hydro plants are generally from the focus of public perception. They can pose a serious danger to various fish species, as it is impossible for many animals to pass through the plant unharmed. The RWTH Aachen interdisciplinary project Sensorfisch, funded by ERS, aims to contribute to a solution to this problem.


What is the sensor fish?

Elena-Maria Klopries, doctoral candidate at the Institute of Hydraulic Engineering and Water Resources Management, proudly shows the device she has been using in her research for roughly the past one and a half years. The sensor fish's size and appearance resemble a film canister. However, the unspectacular exterior is deceiving: the small device is packed with highly sensitive sensors, with which different data like pressure, speed, rotation, and temperature can be measured [Image 1 and 2]. By using the sensor fish in a special testing set-up, a so-called current channel, it is possible to reproduce a fish's path through the various areas of a hydro plant and make detailed measurements. It doesn't not completely replace research with living animals, but – in adherence to strict guidelines – reduces it to an absolute minimum.

Species Extinction as the Initial Problem: Why is research with the sensor fish important?

For fish, which naturally swim along a natural stream of water, passing through a hydro plan can be problematic when they land in the turbines and are damaged. It is particularly problematic for migratory fish species that must migrate from rivers to the sea and whose population levels are threatened by this damage. So-called grills can help to protect the fish from being damaged by the turbines. Originally the grills were used to filter out branches and flotsam from the water in order to protect the turbines from damage. With sufficiently small slat spacing however, the grills can also help to prevent the fishes from entering the turbines [Image 4]. If the slats are incorrectly spaced though, the fish can be hurt by the intended protective measures. It is thus extremely important to size and space the slats in a way that they take both the construction challenges but also the challenges of the fish into consideration.

How exactly can the sensor fish be used in animal protection?

The sensor fish is intended to help avoid an injury to or death of the fish when passing through the hydro plant, says Klopries: "After evaluating the data I can predict where and in what conditions the fish collides with parts of the plant and where pressure rations abruptly change – resulting in a higher risk of injury to the fish." This particularly applies to turbines, which are the original area of application for the sensor fish. The sensor fish can also help to determine the stress on the fish when they come into contact with the grills. Optimizations can then be made in the necessary places in a later step.

Research with the sensor fish as an interdisciplinary …

The researchers have a 2,200 square meter hall with current channels and various other testing set-ups available to conduct trials [Image 5]. It is common for Elena-Maria Klopries to spend a majority of her week here. She regularly discusses her results with other involved colleagues. A range of disciplines are represented in the research project: engineers, behavioral biologists, electrical and control engineers, precision engineers, and bricklayers all contribute to the construction and alterations in the test hall.

… and international project

Because the technology for the sensor fish originated in the US, a collaboration with American scientists has resulted from the project. Dr. Zhiquin (Daniel) Deng from the Pacific Northwest National Laboratory, PNNL for short – where the sensor fish were developed – visited the Institute for Hydraulic Engineering and Water Resources Management in August 2016 for joint research and to exchange ideas [Image 6]. Elena-Maria Klopries reciprocated the visit from July to September 2017 with a stay at the PNNL, during which she could help plan and conduct the implementation of the sensor fish in American hydro plants. "The knowledge I gained in America is a difficult to directly transfer to application in Germany," explains Klopries, "as their plants are great deal larger and the constraints are completely different."

Long-term Importance of the Sensorfisch Project

It needs to be noted that projects like Sensorfisch with its networking with researchers abroad contribute to increasing RWTH's visibility in the research landscape worldwide. Simultaneously, all the participating scientists have the possibility to learn from and with one another. Even if there is still much for Elena-Maria Klopries and her allies to research, the relevance of such projects is unquestionable. The most recent discoveries of the massive decimation of native insect populations in the last three decades once again confirm that in order to maintain ecological balance long term, man-made environmental degradation must be kept at an absolute minimum. Public policy and research must continue to work toward this. One thing is certain: the Sensorfisch project is a wondeful contribution to these efforts.


Additional Literature

Klopries, E.-M.; Kroll, L.; Jörgensen, L.; Teggers-Junge, S.; Schüttrumpf, H. (2016): 20 Jahre aktive Partnerschaft für den Aal an Mosel und Saar. Aalschutz-Initiative Rheinland-Pfalz & innogy SE: Landesamt für Umwelt Rheinland-Pfalz