The invasive black catfish is increasingly threatening local ecosystems in the Czech Republic, causing both ecological and economic problems. Scientists from the Institute of Vertebrate Biology at the Czech Academy of Sciences are therefore monitoring the black catfish, and cooperating with experts from the Mendel University in Brno, local fishing companies and fishing associations on effective regulation methods. The aim is to protect the original biodiversity of aquatic ecosystems while minimising the economic losses caused by this invasive species.
Native to North America and introduced to Europe in the 19th century, the black catfish (Ameiurus melas) is known for its rapid reproduction, aggressive feeding habits and ability to form large populations. Equipped with venomous, lockable spines in its pectoral and dorsal fins, it has few natural predators. In 2003, it was introduced into the Czech Republic through carp stocks from Croatia and is currently found in a few isolated areas such as Mělník, Telč, Kroměříž, Prostějov and Pasohlávky. Despite its limited distribution, the species poses a serious threat to native fish by competing for resources and preying on their eggs and fry, resulting in a significant decline in these native species.
“In areas such as the ponds around Telč, the black catfish causes significant economic damage, with losses estimated at more than CZK 20,000 per hectare. In the case of fishing grounds, it can proliferate to such an extent that the given area is no longer important,” explains Pavel Jurajda from the Czech Academy of Sciences. “To give you an idea, 750 kg of catfish were caught in four days in a recreational pond of 0.7 hectares, the size of a football field, equivalent to a biomass of about 1 t/ha, which is often higher than the biomass of carp in breeding ponds,” he explained.
Students from the Faculty of Fisheries at MENDELU have participated in the catfish reduction project as part of their compulsory practical training. This year they will also participate in the reduction of catfish in Kroměříž, Mělník and Telč. A pilot study carried out last year, in which MENDELU students also participated, demonstrated the effectiveness of various fishing techniques, such as fishing under the outfall with a special net, fishing with traps, catching juveniles with a cast net or with a modified landing net. The most effective method so far seems to be fishing with traps, when the experts caught 2.2 tonnes of adult black catfish from five ponds around Telč, equivalent to 57,000 individuals.
Successful control of the black catfish will take time and effort. Experts are therefore trying to further reduce known populations of this invasive species. At the same time, they are monitoring other areas to detect the possible arrival of new individuals. Black catfish can be confused by the public with the similar American catfish.
“Our goal is to further reduce the population, especially in areas of high density, and to reduce the risk of reckless release of this species into the wild,” Jurajda added. “In cooperation with the town of Telč, local fishing companies, the Vysočina Regional Administrative Organisation and the Moravian Fishing Association, we are planning a regional project focused on further regulation of black catfish in order to protect the biodiversity of our waters.”
