The effect of zooplankton abundance on feeding behaviour and prey size selection in Atlantic salmon, Salmo salar, alevins 1

• Published in: Ecography
• Main Authors: Browman, Howard I., Marcotte, Brian M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1987
• Subjects: Ecology, Evolution, Behavior and Systematics; Atlantic salmon; Salmo salar; Copepods
• Online Access: http://dx.doi.org/10.1111/j.1600-0587.1987.tb00754.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1600-0587.1987.tb00754.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1600-0587.1987.tb00754.x

In an experiment on the effect of zooplankton density on feeding behaviour and prey size selection in Atlantic salmon ( Salmo salar ) alevins, total behavioural activity (feeding, social, ambiguous) was positively related to prey abundance up to a density of 350 items 1 −1 , after which activity peaked. Feeding error (missed attacks and/or rejected ingestions) increased with prey density. The likelihood that an alevin would attack an item upon which it had binocularly fixed (no. bites/no. visual fixes) peaked at densities of 270 items 1 −1 and then declined. Feeding success (no. ingestions per bite or per fixation) also peaked and then declined. Changes in success were reflected in total number of items found in the gut. At high prey abundance (608 items 1 −1 ) only 0.5 – 0.9 mm copepods were preferred components of alevin diets. Over all prey densities, preferred sizes of cladocerans and copepods did not overlap. These results may reflect a perceptual constraint (at high zooplankton densities) on alevin feeding behaviour.