The attachment of dace, Leuciscus leuciscus L., eggs to the spawning substratum and the influence of changes in water current on their survival

Dace lay adhesive eggs in fast‐flowing water which they attach to the gravel substratum. Artificial spates, similar in magnitude to those occurring naturally during the incubation period in early spring, produced transient peaks in egg drift. Even a severe spate caused the loss of only 2.4% of the estimated egg population. Dace eggs are negatively bouyant and, at a current speed of 50 cm S‐1 and a depth of 26 cm, only 2.4% of dace eggs introduced at the surface failed to attach to a gravel substratum within 6 m of the point of release.