Identification of geographic origin of Norwegian spring-spawning herring (Clupea harengusL.) based on measurements of scale anuli

Abstract

The Norwegian spring-spawning herring stock is characterised by a highly variable recruitment. The juveniles are found from the fjords of west Norway to the north-eastern Barents Sea, in a nursery area covering both temperate and boreal waters. High recruitment to the spawning stock is associated with year-classes that are mostly distributed in the Barents Sea as juveniles. The growth, maturation, and recruitment patterns of the fish spending their first years of life in the Barents Sea are distinct from those of the herring further south along the Norwegian west coast. For the management of this stock, it is important to identify the fish from the different nursery areas as they recruit to the fishery and the spawning stock. A method to discriminate the fish from the Barents Sea and the Norwegian west coast nursery areas is based on the width of the scale annuli. The success rate of the derived classification rule is estimated to be about 90%. The proportion of fish from each area in a sample can be estimated with a precision of ±4%.