The importance of Calanus glacialis for the feeding success of young polar cod: a circumpolar synthesis.

ABSTRACT: Understanding the feeding ecology of polar cod (Boreogadus saida) during its first year of life is crucial to forecasting its response to the ongoing borealization of Arctic seas. We investigated the relationships between diet composition and feeding success in 1797 polar cod larvae and juveniles 4.5-55.6 mm standard length (SL) collected in five Arctic seas from 1993 to 2009. Prey were identified to species and developmental stages when possible, measured, and their carbon content was estimated using taxon-specific allometric equations. Feeding success was defined as the ratio of ingested carbon to fish weight. Carbon uptake in polar cod larvae??25 mm and the only copepodite positively selected for. Pseudocalanus spp. copepodites became important replacement prey when C. glacialis left the epipelagic layer at the end of summer. Calanus glacialis was the preferred prey of polar cod, contributing from 23 to 84% of carbon uptake at any stage in the early development. Feeding success was determined by the number of prey captured in larvae??30 mm. As Arctic seas warm, the progressive displacement of C. glacialis by the smaller Calanus finmarchicus could accelerate the replacement of polar cod, the dominant Arctic forage fish, by boreal species.

SUBMITTER: Bouchard C 

PROVIDER: S-EPMC7437650 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature