Assessment of the migration of Atlantic cod (Gadus morhua L.) between the stocks off West and East Greenland in 1984-86 by means of otolith typing

Abstract

A method to identify individual cod originating from either of the nursery areas off West (Davis Strait) or East Greenland (Norwegian Sea, Denmark Strait) is based on a visual classification of individual annuli of the cod otoliths (sagitta) into three different types based on the formation of opaque and hyaline zones. The different hydrographic conditions off East and West Greenland probably affected the growth of the cod and were thus manifested as natural tags, in the form of different annuli of the otoliths. The calculation of emigration and immigration rates using the otoliths as natural tags confirmed the cod migration derived from tagging experiments, ie a one-way migration from West to East Greenland. -from Author