the catfish (Silurus glanis) is one of the invasive species that devastate the Iberian Peninsula, where not only does it seem to have settled, but in recent years it has expanded its domains. Now the institutions are trying to curb its expansion. The next battlefield will be the lower Guadalquivir.
A monster with a mustache.
Despite being a freshwater fish, the catfish stands out for its size, which usually exceeds the two meters and the 100 kilograms. It is, in fact, the largest freshwater fish in Europe. They are usually dark in color, sometimes green or bluish, and have a small dorsal fin and a slimy, scaleless body. However, its most striking feature is its “whiskers”, six perioral barbels that give the many fish in its family the nickname of catfish.
The danger of this species is closely linked to its size: it is a voracious predator that threatens smaller fish and invertebrates such as crabs. It even poses a threat to waterfowl like ducks (or anyone else unlucky enough to find themselves on shore).
It is a fish native to the rivers of central and eastern Europe, but introduced into rivers of the Peninsula in the second half of the 20th century. Although it was introduced for sport fishing, it soon became a threat to fishing activities by decimating the populations of other species.
On alert since 2011.
Already common in the waters of the Ebro, the first sighting of this species in the Guadalquivir basin was made in 2011, when a specimen was detected in the Iznájar reservoir. The Junta de Andalucía has since prohibited the capture of this species in the reservoir but does not have an eradication plan.
Surveillance and control plan.
The species has now been detected in the waters of the lower Guadalquivir, which has worried authorities and environmental groups. This has motivated a study promoted by the Ministry for the Ecological Transition (MITECO) and coordinated by the University of Córdoba. The University of Seville and the Andalusian Agricultural and Fisheries Training and Research Institute (IFAPA) also participate in it.
The objective is, explain from the EFE agency, locate where the specimens of this species live and create a protocol for action and control. Attempts to eradicate this species would be at a critical moment.
In the words of Carlos Fernández Delgado, professor of Zoology at the University of Córdoba, collected by the agency, “when a population is in the first phase of colonization, it is the only time to attack it and once it is established it is almost impossible to eradicate it.”
Ecological and economic danger.
The possible impacts of catfish are not restricted to the ecological but also have ramifications on the economy of the region. Specifically, the promoters of the new control plan mention the risk that the species poses to the red marsh crab (Procambarus clarkii, curiously another invasive species). This species is key for the local packaging industry.
Although this species is not expected to settle in the very saline waters of the Doñana park, it could pose a risk if it entered its waters, especially for some of the birds in the area.
A kind of many.
The catfish is one of dozens of species collected in the Spanish Catalog of Invasive Alien Species elaborated by MITECO itself. It covers varied species, not only animals but also mushrooms Y floors. The catalog not only includes species from the peninsula but also others that pose a risk in other areas of the country.
This particular most wanted list includes algae like killer algaeCaulerpa taxifolia) mammals like the raccoon (procyon lotor), insects like the tiger mosquitoAedes albopictus); Y various fish in addition to the catfish, like its close relative the black catfish (Ameiurus melas), common carp (Cyprinus carpio), or river perch (Perca fluviatilis).
There is hope.
Check invasive species It is a very laborious task but not impossible. One of the most widespread species in Spain is the pampas duster (Selvana Cortaderia), a common plant of riparian areas in the Peninsula, but also an unwelcome host.
In recent months, institutions and associations managed to clean this species 300 hectares on the Cantabrian coast, eradicating some 2,000 outbreaks in which this plant had settled. It is a small step, albeit significant because it is one of the first battles won in the fight against the extension of this plant.
Things are not looking good for now in the case of the catfish expansion. However, the example of the Pampas feather duster can serve as a guide to at least control the damage that species like these can cause in our ecosystems.
Image | Florian Dieter
