The biology of the River lamprey (L. fluviatilis L.) was investigated by relating ecological observations to neurophysiological studies of olfaction. The larval life of L. fluviatilis in British rivers is estimated as 4 1/2 years, and the morphology of spring-caught downstream migrants is compared with that of newly transformed animals. A high proportion of downstream migrants were successfully acclimated to high salinities but could not be induced to feed under laboratory conditions. It is postulated that high autumnal river flows direct the movements of upstream migrants and the hydrographic conditions for spawning are described. The possibility of hybridisation with L. planeri, and the accumulation of lampreys on the spawning grounds are discussed. The brain activity of lampreys was related to that of other vertebrates and the olfactory brain response to stimulation with dissolved chemicals, ''home" and other natural waters was explored. The stimulant effect of river water was enhanced if it had contained lampreys, and the electrophysiological results are discussed in relation to homing and other aspects of the biology of the River lamprey.
|Date of Award||1973|