Behavioural responses of eel (Anguilla anguilla) approaching a large pumping station with trash rack using an acoustic camera (DIDSON)

• Published in: Fisheries Management and Ecology
• Main Authors: van Keeken, Olvin Alior, van Hal, Ralf, Volken Winter, Hendrik, Tulp, Ingrid, Griffioen, Arie Benjamin
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: Fish behaviour; conservation; fish migration; imaging sonar; migration barriers; Anguilla anguilla
• Online Access: https://research.wur.nl/en/publications/behavioural-responses-of-eel-anguilla-anguilla-approaching-a-larg; https://doi.org/10.1111/fme.12427

European eel, Anguilla anguilla L., migrating to the sea encounter many man-made structures that can hamper and delay migration or induce mortality. Studying smallscale behavioural movements in front of these man-made structures could provide insight in further mitigating adverse effects. The behaviour of eel approaching a trash rack in front of a large pumping station was investigated using a dual-frequency identification sonar (DIDSON). Eels approaching the trash rack swam through the rack (40.5%) but also showed turning behaviour at (44.7%) or in front of the rack (14.7%). Eels approaching the rack had varying body positions, predominantly head or tail first, but also curled up into a ball or drifted sideways. After turning in front or at the trash rack, eels showed upstream and downwards swimming towards the canal bottom. The results suggest a stepwise response to potential cues, when firstly the body position is changed in such a way that secondly, later on, enhances eventual fastupstream escapement when perceived necessary. Implications for management of these behavioural observations are discussed.