GillnetSelectivity

Gillnet selectivity is poorly known for most freshwater fish species, particularly for invasive alien species. However, their use to determine mesh selectivity could be essential for establishing management measures, such as selectively remove exotic invasive species. This study aims to assess size selectivity of exotic invasive species in a restored lentic freshwater ecosystem. So, we have analysed gillnet size selectivity based on experimental fishing trials performed by using multimesh gillnets. Twice a year, for 8 years, multimesh nylon gillnets were set up in the Estany d’Ivars i Vila-sana, a restored shallow lake in Catalonia (NE Iberian Peninsula). We caught 4105 individuals belonging to 3 widely-distributed freshwater fish species – 3583 pikeperches (Sander lucioperca (Linnaeus, 1758)), 115 common roaches (Rutilus rutilus (Linnaeus, 1758)) and 407 common carps (Cyprinus carpio, Linnaeus, 1758). The SELECT method was applied to fit six different gillnet selectivity uni- and bimodal models. As a result, bi-lognormal provides the best fit for the 3 species. This is in line with previous studies that found size-frequency data skewed to the right or to multimodal models when high numbers of fish are captured. These results provide the essential information to fish community management with the presence of these invasive alien species.