Spawning in swift water currents: Implications for eggs and larvae
Different behavioural strategies have been developed by fishes to protect their progeny during embryonic and larval development. Many rheophilous species spawn on the stream gravel substratum in swift current areas. This spawning localization ensures a good oxygen supply but involves the risk for the eggs to be swept away by the flow. Salmonids avoid this risk by burying their eggs deeply under the gravel. After hatching, vesicled alevins develop under the gravel until the time of emergence. This article reviews current knowledge about intragravel life, emergence and early dispersion in salmonids, and compares the characteristics of these behaviours and their consequences for survival with the situation encountered by embryos and larvae of lithophilous cyprinid species reproducing in swift water current areas.