Ecological-parasitological method in studies of population biology of beaked redfish <i>Sebastes mentella</i> (Scorpaeniformes: Sebastidae) in the Irminger Sea

Abstract

The results of the analysis of the data set obtained in course of long-term studies of the population biology of beaked redfish Sebastes mentella are used as an interdisciplinary approach in the study of its geographical, biotopic, ontogenetic and phylogenetic features, population structure in the pelagic zone of the Irminger Sea and the adjacent bathyal zone of Greenland and Iceland. The approach is based on the ecological-parasitological method, which involves the use of data on the composition of parasite communities and the occurrence of their individual species as biomarkers for understanding the features of the hydrobionts ecology. The results obtained, which include information on the spatial distribution, functional subdivision of the area, ontogenetic migrations, maturation and growth rate, underwater marking, phenetic, genetic and other features of beaked redfish, made it possible to identify the conditions for divergent formation and significant isolation of its pelagic and benthic groupings, constituting the North Atlantic population. The colonization by this species of great depths of the oceanic pelagial and the near-bottom layer of the bathyal, accompanied with an increase in the rate of sexual maturation and migratory activity in the pelagial, characterizes the direction of the current stage of its phylogenesis. The unity of the pelagic grouping of beaked redfish in the vast water area and throughout the depth of its distribution in the Irminger and Labrador seas is substantiated. It is shown that significant differences in infestation rate between males and females of beaked redfish, stable in time and space, with the only species-specific parasite (the copepod Sphyrion lumpi), serve as a phene of the pelagic grouping of the North Atlantic population of the host.