Behavioural responses of eel (Anguilla anguilla) approaching a large pumping station with trash rack using an acoustic camera (DIDSON)
Keeken, Olvin Alior ; Hal, Ralf ; Volken Winter, Hendrik ; Tulp, Ingrid ; Griffioen, Arie Benjamin - \ 2020
Fisheries Management and Ecology (2020). - ISSN 0969-997X - 8 p.
conservation - Fish behaviour - fish migration - imaging sonar - migration barriers
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 fast
upstream escapement when perceived necessary. Implications for management of these behavioural observations are discussed.