Experimental Study of Rheoreaction of the European River Lamprey Lampetra fluviatilis (L.) Downstream Migrating Smolts under Various Illumination

Abstract

Rheoreaction of the downstream migrating smolts of the European river lamprey was studied in the experimental conditions at illuminations of day and night intensity. It was found that at the daytime the smolts are mostly dormant and if move downstream then in active-passive form (with the head against the stream, and their speed going beyond the velocity). This data is well within the findings on the night downstream migration of the smolts during the 24h period in natural conditions. Thus, the downstream migration of the smolts has an active form.