Introduction: The invasive European catfish (Silurus glanis) is actively spreading across Iberian freshwaters, with no effective management measures in place to control its growing abundance or prevent its establishment in new localities. It poses a severe threat to endemic and already endangered species, and is simultaneously a preferred target by few anglers who continuously promote its spread. The LIFE-PREDATOR project aims to stop the spread of European catfish in lentic systems in Portugal and Italy, particularly in protected areas. Objectives: This talk will present the mid-term results of the LIFE-PREDATOR in Portugal, and discuss the difficulties and future challenges to reduce the size of local populations of European catfish. Methodology: The LIFE-PREDATOR team developed several tasks in Portugal: (1) established the reference situation of fish communities in six reservoirs in the Tagus Basin, using scientific fishing, fish telemetry and eDNA-based tools; (2) determined the optimal protocols for sampling catfish; (3) implemented an early detection programme based on warning teams, data-mining and eDNA tools; (4) developed population control actions in four reservoirs; and (5) organised dissemination events for the general public, anglers, and students from kindergarten to university levels. Results: Overall, there is a grim view about recipient communities in the studied lentic systems, which tend to be dominated by invasive fish species, including common carp (Cyprinus carpio), gibel carp (Carassius gibelio), European catfish, pikeperch (Sander lucioperca), European perch (Perca fluviatilis) and largemouth bass (Micropterus nigricans). At least three new localities harbouring catfish were identified from online data-mining and warning teams. A total of 8 tons of catfish were removed by mid-June of 2025, mostly from the Natural Park of International Tagus. Outreach activities were conducted in nearly 60 schools, reaching more than 5000 students. Moreover, 67 general public events have reached more than 4500 people since the project started (September 2023). Conclusions: Despite its positive outcomes, the LIFE-PREDATOR team has encountered challenges in engaging key stakeholders such as anglers, involving local municipalities, and implementing catfish removal actions in remote areas. Difficulties and challenges in catfish management must therefore be debated in order to assure the after-LIFE implementation across Portuguese protected areas.

Introduction: Knowledge of Iberian freshwater fish fauna among the general public is scarce and generally limited to a handful of species. Moreover, this knowledge gap increases as time goes by, particularly in younger generations, due to the lack of content on native fish fauna in school programmes. Nevertheless, schools across the country are proving increasingly receptive to innovative approaches that engage students in meaningful, real-world learning. Objectives: The LIFE PREDATOR programme leverages this opportunity to educate young people about freshwater fish communities. It aims to prevent the spread of the largest invasive fish in Portugal, the European catfish (Silurus glanis), by engaging students as active conservation ambassadors. Methodology: In inland Portugal, fishing is a cultural practice, and children frequently participate in angling activities alongside friends and family members. By reaching children, the programme simultaneously targets future anglers, potential decision-makers, and a channel for intergenerational knowledge transfer. Results: Thus far, the programme has reached over 5000 students and almost 60 schools, mostly throughout the Tagus basin. Preliminary assessments revealed improvements in students’ ability to name emblematic native fish species like the Iberian nase (Pseudochondrostoma spp.), European eel (Anguilla anguilla) and Iberian barbel (Luciobarbus spp.), and recognise the threats posed by invasives like the European catfish. To ensure national scalability, we have developed learning materials designed for use by teachers across Portugal, which are to be made available for free online. Beyond the dissemination directed to adult fishermen, which is often more demanding, Conclusions: LIFE PREDATOR ensures that knowledge about native river fauna, invasive species, and responsible fishing practices is conveyed through trusted, familiar voices. This intergenerational transmission model has the potential to embed long-lasting behavioural change within future fishing communities.

Introduction: The colossal European catfish (Silurus glanis) is the largest invasive freshwater fish on the Iberian Peninsula, reaching up to 2.8 metres and 130 kg in weight. Its large size makes it a highly valued target for recreational anglers, leading to repeated illegal introductions across several Iberian watersheds. Despite its appeal to anglers, this species is recognised as a high-impact invasive predator with substantial ecological consequences for European freshwater ecosystems. Recently, large catfish aggregations have been reported by anglers and environmentalists in several areas of Portugal and Spain. These impressive aggregations are frequently documented on videos and posted on social media networks (Facebook, WhatsApp groups, etc) or shared directly with our team members. Objective: Such records provide a valuable source of information for identifying the habitats and seasonal periods associated with aggregation behaviours and may therefore support more efficient management and population control actions. Methodology: We compiled information on European catfish aggregation events in Southern Iberia, namely date and location. The catfish aggregations were mapped, and their general habitat characteristics were described. Results: We recorded 10 catfish aggregation events, most of which occurred between May and June. These were generally located in transitional areas between lentic and lotic habitats, especially in narrower river sections. Possible explanations include hydromorphological constraints, seasonal environmental conditions, and species-specific behavioural responses, although these mechanisms require further investigation. Conclusions: Within the LIFE PREDATOR project, which focuses on the management of European catfish in the Tagus watershed, knowledge of aggregation locations is important to direct population control efforts aimed at reducing the abundance of this invasive fish. Moreover, the identification of common habitat characteristics may help predict other potential aggregation sites and improve the planning of future management actions.

Introduction: The most common method for controlling invasive fishes is mechanical removal, although it is time-consuming and operationally demanding. In Portugal, commercial inland fisheries are permitted, but the extent to which they could represent a complementary tool for invasive species control remains unknown. Objective: We compared fish assemblages in two sections of a branch of the Cedillo Reservoir where commercial fishing is allowed (i.e., downstream the Lentiscais bridge) and where it is prohibited under the regulations of the International Tagus Natural Park (i.e., upstream). Methodology: Fish were sampled in 2023 and 2024, using a total of 116 gillnets: 72 downstream and 44 upstream. The proportion of blank nets between sections was compared using Fisher’s exact test. Variations in community composition were assessed using NMDS and PERMANOVA, while homogeneity of multivariate dispersion was evaluated with PERMDISP. Total CPUE was compared between sections using Mann–Whitney tests. At the species level, CPUE were assessed using permutation-based Mann–Whitney U tests adjusted for multiple comparisons using the FDR procedure. The direction and magnitude of between-section differences were quantified using the rank-biserial correlation, and 95% confidence intervals were estimated by section-stratified bootstrap resampling. Results: In total, 20 gillnets yielded no fish, and there was no significant difference in their proportions between sections. Total CPUE per gillnet was significantly higher upstream than in the commercially fished section. Fish assemblage composition differed significantly between sections, and there were no dissimilarities in multivariate dispersion, indicating a genuine, although partial, separation between assemblages. The species contributing most to the dissimilarity between the two sections were Silurus glanis, Cyprinus carpio, Sander lucioperca, and Luciobarbus bocagei, which are also among the main target species for national inland commercial fisheries. Among these species, L. bocagei and S. glanis showed significantly lower CPUE in the commercially fished section, while S. lucioperca showed higher CPUE. Variations in C. carpio CPUE were barely significant. Conclusions: These results suggest that commercial fishing may at least partially influence fish catches and assemblage structure in this reservoir branch. Future studies should partition the influence of commercial fishing from other drivers of assemblage variation to further evaluate whether it may represent a complementary tool for managing fish invasions under specific management strategies.

Freshwater ecosystems in southern Europe are increasingly impacted by fish invasions from central and northern regions, often facilitated by warmer climates and reduced natural-enemy pressure. The European catfish (Silurus glanis), the largest freshwater fish in Europe, is now widely established across various southern European basins, where its high fecundity, ecological plasticity, and predatory behaviour pose significant risks to native communities. Despite its rapid spread, growth dynamics across native and non-native populations remains scatteredly described in studies with different approaches. Objective: This study compares growth rates between native populations in the Czech Republic and non-native populations in Portugal, Spain, and Italy, and assesses whether growth rates are influenced by introduction timelines, reflecting differences in population age and invasion stage. Methodology: Nine populations spanning the native range (central Europe) and non-native range (southern Europe) were analysed. A total of 427 different vertebrae were used to age the fish and growth was modelled using the von Bertalanffy growth function. Generalised linear models were used to identify environmental and demographic predictors of variation in the growth coefficient (K). Moreover, mark-recapture data from the native populatations was also analysed. Results: Preliminary results indicate substantial variation in growth among populations, with higher growth rates exhibited in non-native populations (Iberian), while native populations showed consistently lower growth rates. Growth was primarily associated with population age and minimum temperature, decreasing with increasing population age and increasing under warmer thermal conditions. These patterns suggest faster growth in recently established and warmer populations. Conclusions: Growth dynamics of European catfish vary markedly across native and non-native ranges, driven mainly by thermal conditions and invasion history. Faster growth in warmer and recently established populations may enhance invasion success by accelerating size-at-age and reproductive potential. This study highlights the importance of integrating environmental and demographic factors to improve predictions of invasion dynamics and ecological impacts in freshwater ecosystems.