The low flow of the Onyar River, as it passes through the center of the city of Girona, has forced the City Council to carry out a new day of electrofishing. This morning, a specialized brigade combed a stretch of river in order to remove the maximum number of fish to avoid episodes of mass mortality due to lack of oxygen in the water.
As was done last April, carp, an exotic species that is the most abundant in that stretch of the river, will be sacrificed, as mandated by regulations. The native species that are found, such as mountain barbel, eel or catfish, will move to the Ter River.
This wildlife rescue plan wants to avoid a sudden and massive mortality of the species that inhabit this stretch of river, caused by the reduction in flow and poor water conditions. Two elements that have been aggravated by the lack of precipitation.
The system used for captures is electrofishing. Through the use of devices, electric fields are created in the water that allow fish that are within reach of the generated field to be stunned, the amplitude of which ranges between one and six meters. This electric field causes the species to become immobilized and can be removed from the water more easily.
The main fish present in this stretch of the river is carp, an invasive species that was introduced to Catalonia about 120 years ago. Being an exotic species, regulations require it to be sacrificed. Other foreign fish such as percasols, rutiles or piscados are also found in the Onyar River.
