Feeding and growth of Atlantic cod (Gadus morhua L.) in the eastern Baltic Sea under environmental change

Stefan Neuenfeldt*, Valerio Bartolino, Alessandro Orio, Ken Haste Andersen, Niels Gerner Andersen, Susa Niiranen, Ulf Bergström, Didzis Ustups, Nataliia Kulatska, Michele Casini

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Five decades of stomach content data allowed insight into the development of consumption, diet composition, and resulting somatic growth of Gadus morhua (Atlantic cod) in the eastern Baltic Sea. We show a recent reversal in feeding level over body length. Present feeding levels of small cod indicate severe growth limitation and increased starvation-related mortality. For young cod, the low growth rate and the high mortality rate are manifested through a reduction in size-at-age. The low feeding levels are likely the result of a decrease in benthic prey abundance due to increased hypoxic areas, while decreasing abundances of pelagic species in the area of cod distribution have prevented a compensatory shift in diet. Our study emphasizes that environmental forcing and the decline in pelagic prey caused changes in consumption and growth rates of small cod. The food reduction is amplified by stunted growth leading to high densities of cod of smaller size competing for the scarce resources. The average growth rate is negative, and only individuals with feeding levels well above average will survive, though growing slowly. These results suggest that the relation between consumption rate, somatic growth and predatorprey population densities is strongly environmentally mediated.
Original languageEnglish
Article numberfsz224
JournalICES Journal of Marine Science
Volume77
Issue number2
Pages (from-to)624-632
Number of pages9
ISSN1054-3139
DOIs
Publication statusPublished - 2020

Keywords

  • Baltic Sea
  • Bioenergetics modelling
  • Environmental change
  • Gadus morhua
  • Growth
  • Predation
  • Stomach data

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