Universal Behavioural Adaptations in Lampreys and Salmonids

Equal adaptations to environmental conditions form in representatives of various taxonomic groups dwelling in similar conditions during the evolutionary process. Multiple ecological parallels were found in salmonid fishes and lampreys which inhabit basins of boreal latitudes. Migrations of various directions and distances are integral part of life cycles of salmonids and lampreys. These migrations have definite patterns which are in relations with environmental conditions. All migrations occur in the time when conditions are optimal for this. Downstream migrations (including seaward migrations) are performed by ammocoetes and juveniles of salmonid fishes. Juveniles are more vulnerable to negative environmental conditions than mature organisms. General patterns and certain mechanisms of downstream migration were studied on the example of Arctic lampreys Lethenteron camtschaticum ammocoetes and juveniles of salmonids of genera Oncorhynchus, Parasalmo, Salvelinus in several rivers of Kamchatka (the Far East of Russia). It was argued that downstream migration is a unique adaptation for development and optimal exploitation of the habitat in various groups of low vertebrates.