@ Cynthia Adina Kirkwood
Biggest Fish Caught in Tagus River: 2.17-Meter Predator
Updated: May 14, 2022
Joao Lobo Cristino donated his European catfish to the Center for Marine and Environmental Sciences (MARE) for study of the invasive species.
A fisherman ‘born’ on boats tangled alone with a European catfish fish that out-measured him in length at 2.17 meters (7.12 feet): the biggest fish caught in the Tagus River.
“It didn’t give much of a fight, but I had to be careful because it was very strong,” said Joao Lobo Cristino, 63, who lived on boats until he was 12. He returned to fishing in the Tagus 30 years ago in the municipality of Azambuja, Lisbon District. Cristino centers his activity in Porto da Palha, where he made his spectacular catch on May 4 at 7:40 a.m., reported Correio da Manha (May 6).
The fisherman tied up his catch on the boat and headed to the ramp. Other anglers rallied to his side to help drag the 60-kilogram (132.28-pound) fish ashore.
After a team of biologists weighed and measured the European catfish, Cristino donated it to the Center for Marine and Environmental Sciences (MARE) for the study of the movement and food chain of this invasive species.
Fisherman Joao Lobo Cristino’s catch broke the previous record of 56 kilos (123.46 pounds) and 1.98 meters (6.50 feet), also a European catfish, reported Correio da Manha (May 6).
The fisherman lamented: “It is a predator that eats everything, including lamprey. It also destroys nets, which can cost 300 euros. It is a pest only defended by some sport fishermen.”
Felipe Ribeiro, a MARE researcher at the Faculty of Sciences of the University of Lisbon said to Correio da Manha: “It is a species that reaches large dimensions: it has no predators.”
The European catfish already has been detected in the River Douro.
“It is important that the species isn’t taken to other rivers,” said researcher Felipe Ribeiro.
The catfish is an invasive species that becomes dominant. In the Po River, in Italy, the species first appeared in the 1950s. Today, 70 percent of the fish caught there are European catfish.
The Instituto da Conservaçao da Natureza e das Florestas (ICNF) is working on a plan of action to control the European catfish along with a study about the prevention and management of the introduction and propagation of invasive species, reported Correio da Manha. The ICNF is a Portuguese government agency established in 2012.
In Portugal, 20 invasive fish species have been identified with new species being detected at an unprecedented rate of one every two years, according to European catfish (Siluris glanis) movements and diet ecology in newly established population in the Tagus, University of Lisbon (2019), for which Felipe Ribeiro served as an advisor.
“The European catfish was one of the more recent introductions,” according to the University of Lisbon paper, “This top predator, native to Central and Eastern Europe, was first introduced in Spain and dispersed along the Tagus until reaching Portugal, probably helped by human actions.”
The catfish arrived in the Portuguese Tagus between 2006 and 2008, reported Correio da Manha.
Small catfish can lay 80,000 eggs. The recent catch, which must be 10 years old, could have laid as many as 500,000 eggs, said Ribeiro.
“There are hundreds of thousands of catfish in the Tagus, and it is necessary to mitigate the impact of the species,” emphasized the researcher.
The 2019 scientific paper said: “The fact that this is a recent arrival represents an opportunity to study the early stages of invasion and how this species may shape the aquatic community around it. This work focuses on two aspects of the habits of this species . . . : movement and diet.
“This species exhibited great spatial fidelity (84 percent). However, some individuals (16 percent) were capable of long-distance movements (up to 11.5 kilometers) that can help its dispersal.
“The observed eating habits are worrisome. This species has the ability to prey on the entire spectrum of available prey. . . . In the moving-water sections of the Tagus, a large percentage of their diet is composed of native fish and freshwater shrimp. Predation of European eel and sea lamprey represents a source of additional pressure on these endangered species. Catfish from still-water habitats, by contrast, fed almost exclusively on crustaceans (freshwater shrimp and red crayfish) with very few fish, which were mostly non-native.
“Biological invasions are one of the main causes of biodiversity loss in the world. The phenomenon of species introduction affects almost all ecosystems.
“Freshwater ecosystems are highly biodiverse . . . However, they are under tremendous pressure, between the consequences of climate change, pollution, and regulation of river systems (e.g. dams) that have left them vulnerable. Introduced species have been easier to establish, making these environments one of the most affected by introduced species.”