Feeding ecology of age-0 polar cod (Boreogadus saida) in the Greenland Sea

Abstract

Polar cod (Boreogadus saida) play a crucial role as a key species in Arctic marine ecosystems. The importance of successful feeding of particularly their sensitive early life stages for survival and later recruitment into the adult population is known. This study investigated the diets of age-0 polar cod in the Greenland Sea (Northeast Greenland) during the summer and fall of 2017, focusing on regional feeding patterns and prey preferences. Stomach contents were analyzed in conjunction with environmental data, including oceanographic conditions and zooplankton distributions, to identify and quantify prey taxa, estimate ingested carbon contents, and assess prey selectivity. The findings revealed two regional groups characterized by differing oceanographic conditions and dietary patterns. Consistent with findings from other regions, Calanoid copepods were the predominant and preferred prey across both groups. Age-0 polar cod in the shelf group consumed a higher number of prey items with lower overall carbon contents, showing a preference for Calanus spp. nauplii. The basin group ingested fewer, but higher carbon content prey items, with a preference for Pseudocalanus spp. nauplii. These results illustrate the differences in polar cod diets at a regional scale. Investigating the feeding ecology of early life stages in East Greenland is an important tool to understand their role in a changing Arctic.