A method for estimating the consumption of capelin by cod in the Barents Sea

Abstract

A method for estimating how much capelin ( Mallotus villosus Müller) is consumed by cod ( Gadus morhua L.) during the winter capelin spawning migration has been developed. The method is based on an analysis of cod stomach content data and a model for stomach evacuation rate, and rests on various assumptions about temperature, stock size, and age distribution of cod, an initial stock size estimate of maturing capelin, and overlap between cod and capelin in space and time.

The methods is now in use by the ICES Atlanto-Scandian Herring and Capelin Working Group for stock assessment purposes. The maximum amount of Barents Sea capelin consumed by north-east Arctic cod in winter of the years 1991-1993 has been estimated in the range 500 000-800 000 tonnes. This is a substantial part of the total amount of capelin at the start of the spawning migration, which in these years ranged from 2.1 to 2.6 million tonnes.