USE OF THE LATERAL-LINE IN PARTICULATE FEEDING IN THE DARK BY JUVENILE ALEWIFE (ALOSA-PSEUDOHARENGUS)

The alewife (Alosa pseudoharengus) is an obligate planktivore which uses a variety of methods for capturing zooplankton. Alewife eat Mysis relicta, especially larger individuals, at night during a vertical migration by both predator and prey. We proposed and tested the hypothesis that alewife use the lateral line to sense prey and feed particulately (single prey at a time) in the dark. We used Daphnia magna and Artemia salina adults as prey. Prey densities were such that they did not elicit filter feeding. Observations using infrared video showed that alewife captured individual prey and bit at a vibrating inert bead. We concluded that under appropriate conditions, alewife were size selective and that streptomycin (which blocks the lateral line sensory cells) eliminated this feeding behavior.