FISHERMEN on the Tarn are used to seeing birds diving into the water to catch fish – but have now spotted fish lunging out of the water to catch birds.
The fish – which were up to two metres long – were spotted surging out of the river in the middle of Albi to snap up pigeons drinking and preening themselves in the shallows.
Fishermen had talked among themselves for some time about the catfish and researchers from the Laboratoire Évolution & Diversité Biologique at Toulouse decided to investigate. They confirmed the claims and filmed the European catfish hunting pigeons on the riverbanks.
See the video of the catfish in action here on YouTube
The fish often had half their bodies out of the water as they snapped up the birds.
In a report published on open access science journal PLoS ONE the researchers, led by Julien Cucherousset, said they set up a watch from a bridge above a shinglebank in Albi where pigeons gathered for drinking and cleaning.
Over 24 three-hour sessions in 2011 they spotted 54 attempts by catfish to catch birds – with 15 successful and the bird dragged under the water and eaten. In one case the fish was completely out of the water – but missed its target.
However, birds standing in the water were not targeted by the fish, which only chased birds moving and causing vibrations in the water; walking or cleaning themselves.
The researchers said it was like watching killer whales surgeing out of the water to catch seals on the beach.
The catfish, Silurus glanis, is the largest freshwater fish in Europe and was first introduced into the river in 1983. The researchers say they are simply adapting to catch whatever food is available. They said in the report: “Some individuals in introduced predator populations may adapt their behavior to forage on novel prey in new environments, leading to behavioral and trophic specialization to actively cross the water-land interface.”
Tissue samples showed that some catfish did not eat pigeons at all, while for others it made up 80% of their diet. One of the research team, Frédéric Santoul, told Le Monde : “These catfish were not interested in their usual prey, chub and barbell, which could pass close by without sparking any attack.”
He added that the pigeons had still not wised up to the dangers – they still looked to the skies for possible danger, from hawks.