Environmental Biology of Fishes

, Volume 97, Issue 4, pp 343–355 | Cite as

Dietary niche partitioning in sympatric gadid species in coastal Newfoundland: evidence from stomachs and C-N isotopes

  • D. Craig KnickleEmail author
  • George A. Rose


The feeding habits of co-occurring gadid species Atlantic cod (Gadus morhua) and Greenland cod (Gadus ogac) in coastal Newfoundland waters, examined using stable isotope (δ 13C and δ 15N) and stomach content analysis, indicated little dietary niche overlap and interspecific competition for food resources despite similar trophic levels. Both species consumed a variety of invertebrates and fish but showed a preference for different prey items. Polychaetes, fish and small crustaceans dominated G. ogac stomach contents while small crustaceans, in particular hyperiid amphipods and fish, dominated those of G. morhua. In general, G. morhua consumed more pelagic prey and had a significantly more pelagic (more negative) δ 13C signature while G. ogac consumed primarily benthic prey and had a more benthic (more positive) δ 13C signature. δ 15N levels were similar in these species suggesting similar trophic positions, with levels increasing with fish length in both species. Dietary overlap was not significant in both stomach and stable isotope analyses. We conclude that interspecific competition for food is low between G. ogac and G. morhua and is unlikely to be a factor in the slow rebuilding of Atlantic cod in this region.


Gadus Cod Niche partitioning Diet overlap Stable isotopes Stomach contents 



We thank E. Stern, D. Pike, and T. Clenche for support in the field and K. Krumsick and S. Fudge for lab assistance. This work was approved by the Animal Care Committee at the Memorial University of Newfoundland and was funded by grants from the Newfoundland and Labrador Department of Fisheries and Aquaculture and the Natural Sciences and Engineering Research Council of Canada to GAR, and a scholarship from the Institute for Biodiversity, Ecosystem Science & Sustainability (IBES), Department of the Environment of Newfoundland and Labrador, to DCK


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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  1. 1.Centre for Fisheries Ecosystems ResearchFisheries and Marine Institute of Memorial University of NewfoundlandSt. John’sCanada

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