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Related Experiment Video

Updated: May 14, 2026

Methods for Image-based Surveys of Benthic Macroinvertebrates and Their Habitat Exemplified by the Drop Camera Survey for the Atlantic Sea Scallop
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Coexisting Atlantic Cod Ecotypes in the Barents Sea: An Issue for Managing Fisheries.

Torild Johansen1, Per Erik Jorde2, Jon-Ivar Westgaard1

  • 1Institute of Marine Research (IMR) Tromsø Norway.

Evolutionary Applications
|May 13, 2026
PubMed
Summary

The Northeast Arctic cod (NEAC) and coastal cod (CC) mix in the Barents Sea, with genetic evidence of CC and hybrids found offshore. Otolith type is an unreliable indicator of cod ancestry.

Keywords:
Gadus morhua Lhybridsmonitoringotolithsstock origin

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Published on: September 5, 2018

Area of Science:

  • Marine Biology
  • Population Genetics
  • Fisheries Science

Background:

  • The Northeast Arctic cod (NEAC) is the largest Atlantic cod stock, facing climate change and recruitment issues.
  • NEAC is presumed a single biological population, but it overlaps with coastal cod (CC) in Norwegian waters.
  • CC is managed as a distinct stock, raising questions about population structure and management.

Purpose of the Study:

  • To investigate the population structure of cod in the Barents Sea.
  • To identify potential mixtures of NEAC and CC ecotypes and their hybrids.
  • To assess the reliability of otolith analysis for determining cod ancestry.

Main Methods:

  • Analysis of otoliths from 3900 cod specimens.
  • Genotyping of cod to determine genetic ancestry and population structure.
  • Surveys covering NEAC spawning and feeding grounds in the Barents Sea.

Main Results:

  • First-time inference of CC presence and NEAC × CC hybrids far offshore in the Barents Sea.
  • CC distribution was heterogeneous, with higher concentrations in the west (including Svalbard), east, and near the Norwegian coast.
  • Most identified CC individuals possessed NEAC-type otoliths, indicating otolith morphology reflects environment, not genetics.

Conclusions:

  • Cod ecotype mixing occurs in the Barents Sea, challenging the assumption of a single NEAC population.
  • Otolith analysis is a poor predictor of genetic ancestry in this context, likely reflecting environmental influences.
  • Further research is crucial to understand the dynamics of stock mixing and its management implications for cod fisheries.