MEPS 520:235-243 (2015)  -  DOI:

Effects of copepod size on fish growth: a model based on data for North Sea sandeel

Mikael van Deurs1,3,*, Christian Jørgensen2, Øyvind Fiksen2

1DTU Aqua National Institute of Aquatic Resources, Technical University of Denmark (DTU), Jægersborg Alle 1, Charlottenlund Castle, 2920 Charlottenlund, Denmark
2Thormøhlensgate 53B 3rd floor, Department of Biology, University of Bergen, PO Box 7803, 5020 Bergen, Norway
3Present address: Lund University, Sölvegatan 37, International Postal Code 50, Lund, Sweden
*Corresponding author:

ABSTRACT: In productive marine off-shore ecosystems, the flow of energy from zooplankton to large predators is channeled through a few species of short-lived, highly abundant schooling planktivorous fish. There are indications that these species respond to qualitative and phenological changes in the zooplankton. If so, the climate-induced alterations of the local copepod communities that we see in temperate and arctic regions may influence the energy flux in marine food chains. In order to investigate how different processes contribute to the relationship between copepod size and fish growth, we merged 2 mechanistic models from relevant data: (1) a model of the bioenergetics and stomach filling/evacuation dynamics, and (2) a Holling type II functional response model that encompasses visual range from basic principles. The model predicts that going from a situation where large Calanus copepods (2 mm) dominate the prey field of lesser sandeel Ammodytes marinus in the central North Sea to a situation where only relatively small (1 mm) and less energy-rich copepods are available roughly halves the energy intake of sandeels even if prey biomass concentration remains constant. Visual constraint on foraging was the most important factor, followed by handling time limitation and prey energy content. These limitations became stronger with increasing fish length, showing that copepod size and energy content have a strong effect on the specific growth potential of these fish.

KEY WORDS: Prey preference · Bioenergetics · Optimal foraging · North Sea regime-shift · Climate change · Ammodytes · Holling disc · Calanus · Handling time limitation · Food quality

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Cite this article as: van Deurs M, Jørgensen C, Fiksen Ø (2015) Effects of copepod size on fish growth: a model based on data for North Sea sandeel. Mar Ecol Prog Ser 520:235-243.

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