Estimation of glass eel (Anguilla anguilla) exploitation in the Severn Estuary,England

Mark-release-recapture trials were conducted to determine the exploitation rate of glass eel Anguilla anguilla (L.) by handheld dip nets in the Severn Estuary in the spring of 2020. The glass eel were marked with Rhodamine B at a concentration of 0.1 g/L, 200 glass eel/L for 4.5 hr and then placed in fresh water for 36–48 hr to monitor mortality. In trial 1, 891 ± 100 of the 20,455 glass eel were recaptured while in trial 2,373 ± 172 of the 27,923 glass eel released were recaptured. The exploitation rate was estimated to be 4.36% (±0.49) in trial 1 and 1.33% (±0.62) in trial 2. The size of the glass eel population from trial 1 was estimated to be 24.69 t (22.46 – 28.81), and the overall exploitation rate of the fishery for the season was 7.8% (6.7% – 8.6%). Comparisons are made with studies in other estuaries and with conservation targets set by the EU Eel Regulation and the Eel Management Plan for the River Severn. The study suggests the fishery is not the main cause of the Severn RBD failing to meet escapement targets.