Assessing the use of Inland Wetlands by fish in the Lower Tagus Basin (Portugal)

The study consisted in one single sampling event for each of the inland wetlands, between 6th of May to 10th of June 2021, using a combination of multiple techniques to assess community composition, which included electrofishing, seine netting and minnow traps.This dataset encompasses data only from identified freshwater fish with a total of 8 272 records from 13 different species, where 5 are native (one regional endemics) and 8 introduced species, namely native species found European eel (Anguilla anguilla), Thinlip grey mullet (Chelon ramada), Southern Iberian spined loach (Cobitis paludica), Lisbon arched-mouth nase (Iberochondrostoma olisiponense) and Iberian barbel (Luciobarbus bocagei).

Introduced species were Bleak (Alburnus alburnus), Black bullhead (Ameiurus melas), Common carp (Cyprinus carpio), Goldfish (Carassius sp.), Eastern mosquitofish (Gambusia holbrooki), Pumpkinseed sunfish (Lepomis gibbosus), Largemouth bass (Micropterus nigricans) and Pikeperch (Sander lucioperca). This study highlights that fish communities are dominated by non-native fish, although some inland wetlands still harbour threatened native species, including regional endemics.