Mortality induced by electrofishing and handling in five young-of-the-year cyprinids: effect of the fish size, species and anode size

Abstract

Immediate mortality induced by electrofishing and handling of young-of the-year (YOY) fish of five cyprinid species (bitterling Rhodeus amarus, chub Leuciscus cephalus, bleak Alburnus alburnus, barbel Barbus barbus, roach Rutilus rutilus) was quantified during routine YOY fish monitoring (point abundance sampling with backpack electrofisher, in situ identification and measurement). Sampled, identified and measured fish were held in screened containers immersed in the river for 5 h after electrofishing. Bleak exhibited significantly higher mortality (17%) than all other species (1–3%). Mortality decreased significantly with fish length; fish <35 mm exhibited the highest mortality. Anode size (10, 20, and 30 cm diameter) had no direct effect on mortality. Point abundance electrofishing with in situ identification and measurement is a safe method for sampling riverine YOY cyprinids.