Technology
AllWaysFish fish protection systemÂ
When we encounter an electric field in water
Low and alternating electric fields in aquatic environments occur naturally or can be generated by devices. Electricity in the form of an electric field generated in the aquatic environment is a widely used technology throughout the world, mainly for catching fish. These are mostly small size and low power portable devices used for spot fishing. Systems that generate electric fields in water are also mounted on boats designed for electrofishing on a larger scale.
What are electrical barriers and how are they constructed?
AllWaysFish Electrical BarriersAllWaysFish Electrical Barriers are devices used to block migrating fish and to direct them into migration paths such as fish ladders. They generate an electric field of an appropriate shape and intensity, which constitutes an invisible blockade for fish, at the same time not harming them when in contact with the electric field. It is an impulse field modelled within the frequency range from 10Hz to 10kHz and intensity from 0.1V/cm to 0.6V/cm.
An electric field is generated between positive and negative electrodes placed in an aqueous medium. The number of electrodes, their size and mutual positioning define the field shape and the space in which the electric field is generated. The electrodes can be mounted vertically in rows as lines of positive and negative electrodes between which the field is generated alternately in rows or individually, e.g. on the sides of water channels. The way the electrodes are mounted is determined at the individual project stage.
Depending on the object and purpose of the electric barrier, it can affect the body of fish by transverse or longitudinal lines of electric field force. When technical conditions do not allow us to install electrodes generating longitudinal lines of force, we use side electrodes generating transverse lines of force. Both types of fields provide the possibility to achieve high efficiency, but in the most demanding cases we design and use solutions that are a hybrid of both. Hybrid solutions are usually more expensive to implement but give much more space for field modelling and more effective action on the fish.
Effectiveness of AllWaysFish electric barriers
The effectiveness of electrical barriers depends on many factors that must be considered at the design stage. Electric barriers are not a solution that can be easily duplicated and installed 1 to 1 on different objects.
There are many factors that we consider in the design and implementation of electrical barriers in order to achieve the highest possible effectiveness.
These include:
- fish migration routes
- the structure of the river channel at the electric barrier installation site
- the type of bottom and the vegetation present
- cross-sectional dimensions at the installation site
- barrier environment: walls, steel elements
- water conductivity and its variability
- fish species to be affected by the barrier
- fish dimensions
- water flow rate
- direction of flow, direction of fish migration
- pollutants that travel downstream
- annual water level fluctuations
- existence of ice conditions
- undulations (in case of installation on water reservoirs)
- contamination level of electrodes
- -the shape of the electric field determined by the arrangement of electrodes and electrode supply voltage.