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Marine Ecology Progress Series

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MEPS 677:141-159 (2021)  -  DOI: https://doi.org/10.3354/meps13878

Effects of sea ice cover, temperature and predation on the stock dynamics of the key Arctic fish species polar cod Boreogadus saida

Nicolas Dupont1,*, Joël M. Durant1, Harald Gjøsæter2, Øystein Langangen3, Leif Christian Stige1,4

1Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, 0316 Oslo, Norway
2Institute of Marine Research, Nordnes, 5817 Bergen, Norway
3Section for Aquatic Biology and Toxicology (AQUA), Department of Biosciences, University of Oslo, 0316 Oslo, Norway
4Norwegian Veterinary Institute, 1431 Ås, Norway
*Corresponding author:

ABSTRACT: Climate change has large effects on population dynamics of fish species in high latitude ecosystems. Arctic fish stocks experience multiple pressures with changing abiotic living conditions and increased competition and predation from boreal species. However, there are many unknowns regarding how environmental change influences the dynamics of those populations. Here, we focused on the Barents Sea polar cod, a pan-Arctic zooplanktivorous key fish species physiologically and ecologically adapted to the presence of sea ice. We developed an age-resolved Bayesian state-space model of the dynamics of polar cod based on 30 yr of survey data (1986-2015). Using this model, we quantified how inter-annual changes in abundance were associated with abiotic variables (temperature and sea ice cover) and biotic variables (prey biomasses and a predation index). Using the model output, we used a hindcast scenario approach to investigate to which degree the observed variations in total population size were related to the abiotic or biotic variables. Our results showed that variation in abundance of young polar cod (ages 0 and 1) was best explained by abiotic variables while variation in the older age groups (ages 3 and 4) was best explained by predation. Hindcast scenarios showed that the abiotic variables had a more evident effect than predation on population dynamics, but none of the variables we considered could explain the drastic population decline observed in recent years. Our work shows the advantages of studying age-specific responses as a stepping stone to understand changes at the population level.


KEY WORDS: Boreogadus saida · Sea ice · Temperature · Predation · Barents Sea · Arctic · Population dynamics · State-space model


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Cite this article as: Dupont N, Durant JM, Gjøsæter H, Langangen Ø, Stige LC (2021) Effects of sea ice cover, temperature and predation on the stock dynamics of the key Arctic fish species polar cod Boreogadus saida. Mar Ecol Prog Ser 677:141-159. https://doi.org/10.3354/meps13878

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