Polar Cod (Boreogadus saida) Stomach Contents from 5 Arctic Seas - Fine resolution taxonomy

• Main Authors: Bouchard, Caroline, Fortier, Louis
• Format: Dataset
• Language: unknown
• Published: Canadian Cryospheric Information Network 2019
• Subjects: Arctic; Boreogadus saida; Calanus glacialis; polar cod; Copepods
• Online Access: https://dx.doi.org/10.21963/13131; https://www.polardata.ca/pdcsearch/PDCSearch.jsp?doi_id=13131

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 2014. 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 < 15 mm was sourced primarily from calanoid copepods eggs and nauplii which were positively selected from the plankton. With increasing length, carbon sources shifted from eggs and nauplii to the copepodites of Calanus glacialis, C. hyperboreus and Pseudocalanus spp. Calanus glacialis copepodites were the main carbon source in polar cod > 15 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 < 13 mm and by the size of prey in juveniles > 25 mm.