PROJECT DESCRIPTION
BACKGROUND
Native to eastern Europe and western Asia, the wels catfish (Silurus glanis) is now established in many countries outside its native range. In Mediterranean countries, where temperatures are more favourable, it is considered highly invasive, threatening native fish and other biodiversity, mostly through predation and competition. This catfish is the largest freshwater fish species in Europe and in the introduced range, with adults at least twice as large as native predators. It is highly adaptable, capable of catching and ingesting a wide range of prey, long lived and fast growing. S. glanis also carries pests and diseases that may adversely impact native fish. Due to its large size, very fast metabolism and aggressive behaviour during the spawning period, the species has a great advantage compared to native top predators. By feeding on previously unexploited resources, such as terrestrial prey and larger native fishes, the catfish can alter ecosystem food webs by creating new links between groups of organisms or via novel predation pressure, often adapting easily to new local conditions.
While the species’ distribution in Italian rivers is well known, few studies have been conducted in lakes. Nevertheless, harvest data from commercial fisheries show a dramatic increase of the species in the last 5-10 years. In Portugal, the catfish was first introduced in 2008 in the Tagus River but it is now present in other sites, too. Although information on catfish abundance in reservoirs (i.e. lentic habitats) is still scarce, data from fishers’ and anglers’ records, as well as from recent field surveys, show a substantial expansion of the catfish.
The pre-operational context of LIFE PREDATOR has been chosen to include lakes with different morphological characteristics (depth and size), different stages of colonisation and different levels of catfish abundance, including lakes where the species has not yet been reported but is likely to be present in the near future.
The project area includes 23 lakes in northern Italy, 25 reservoirs (artificial lakes) in Portugal and 2 in Czechia (50 in total), divided in 4 types, according to their area and depth.
OBJECTIVES
LIFE PREDATOR aims to develop a transnational strategy for managing invasive wels catfish in southern European aquatic systems, thereby contributing to implementation of the EU Regulation on Invasive Alien Species. It will focus on natural and artificial lakes in Italy and Portugal, where populations are established and spreading across all river basins, with potentially severe impacts on native fauna and aquatic ecosystems.
The project is based on an integrative and engaging approach. Control and eradication actions will be designed and implemented, and their effects on native biodiversity, ecosystem functioning and ecosystem services evaluated. Other measures planned include the development of an early warning system, based on environmental DNA, and use of citizen science. By engaging key stakeholders from the beginning, the project aims to promote long-term effectiveness and efficiency in invasion management of catfish. Moreover, it hopes to ensure that lessons learned are made available for other similar southern European aquatic systems that are prone to catfish invasion or already invaded by this species.
The specific objectives are to:
- Develop, test, apply and disseminate an effective early detection system in lakes;
- Implement a network of ‘warning teams’ composed of properly trained citizen scientists (fishers, anglers and citizens) in Italy and Portugal;
- Develop, test, apply and disseminate effective and selective methods of capture to control the catfish population in lakes and reservoirs;
- Prevent the introduction and further spread of the catfish by tackling the main vector (transfer mechanism) of its introduction;
- Raise awareness of the public and target groups about the impacts of invasive fish species, especially the catfish, through a communication and outreach campaign;
- Control and eradicate catfish populations in large and small lakes and reservoirs by reducing the biomass. In particular:
- Reduce by 10% the catch-based biomass of catfish in Lake Maggiore, Cedillo Reservoir and Fratel Reservoir (39 tons, 6 tons and over 4 tons removed, respectively);
- Reduce by 90% the catch-based biomass in 5 small Italian Natura 2000 lakes (about 7 tons in Lake Comabbio, almost 2 tons in Lake Avigliana Grande, over 1 ton in Lake Avigliana Piccolo, 0.6 tons in Lake Sirio and 0.06 tons in Lake Campania); and
- Reduce by 50% the catch-based biomass in Belver Reservoir (more than 1 ton) and Meimoa Reservoir (0.6 tons);
- Improve the ecological status of lake ecosystems, by reducing the abundance of catfish and other exotic invasive fish species during sampling campaigns and removal activities; and
- Increase the use of catfish as food, reducing discards of unexploited catfish and promoting its use.
