Intra‐annual variation in feeding of Atlantic cod Gadus morhua: The importance of ephemeral prey bursts

P. Grønkjær*, R. Ottosen, T. Joensen, L. Reeve, E.E. Nielsen, R. Hedeholm

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Seasonal prey bursts are important for the lifecycles and energy budgets of many predators. Here we document the diet and, especially, the importance of the ephemeral occurrence of capelin as prey for Atlantic cod (Gadus morhua) in Godthaabsfjord, west Greenland, over an annual cycle. The cod showed clear differences in diet composition on the eleven sampling dates resulting in a spring–summer, late summer‐autumn and winter cluster. Moreover, a single sampling date, May 12th, was defined by cod gorge feeding on spawning capelin, which led to average stomach contents 4.3 times higher than the average for the remaining sampling dates. Changes in nitrogen stable isotope values from April 22nd to July 7th in cod liver and muscle tissue was used to calculate the consumption of capelin. Based on this, the consumption of capelin varied between 538–658 g wet weight for a 1.3 kg cod. Using published consumption/biomass estimates and observed growth rates, the capelin intake corresponds to 10.1% – 33.3% of the annual food consumption and accounts for 28.1% – 34.5% of the annual growth of the cod. The present study documents the omnivorous feeding mode of Atlantic cod, but highlights the utilization and importance of ephemeral prey bursts for the annual energy budget of the cod. We hypothesize that access to capelin is critical for the post‐spawning recovery of Godthaabsfjord cod.
Original languageEnglish
JournalJournal of Fish Biology
Volume97
Issue number5
Pages (from-to)1507-1519
Number of pages13
ISSN0022-1112
DOIs
Publication statusPublished - 2020

Keywords

  • Atlantic cod
  • Diet
  • Capelin
  • Stable isotopes
  • Consumption
  • Greenland

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