The effect of fasting, prolonged swimming, and predator presence on energy utilization and stress in juvenile walleye (Stizostedion vitreum)

S. Czesny, J. Rinchard, M. A.Garcia Abiado, K. Dabrowski

Research output: Contribution to journalArticle


We evaluated how two diets with different lipid levels (4% vs. 10%) influenced nutrient expenditure in juvenile walleye Stizostedion vitreum subjected to starvation, prolonged swimming, and predator presence. We also determined how exercise and predator presence influenced stress indicators such as blood plasma cortisol and glucose. Groups of six fish were placed in triplicate rectangular wire cages per treatment and submerged randomly in three artificial stream compartments at a water temperature of 14°C. Three treatments were established: (A) no water current and no predator, (B) water current (1.5 body lengths s-1) and no predator, (C) water current and predator. Six 1-year-old muskellunge (Esox masquinongy, 28.4±2.3 cm) were used as predators. They were allowed to swim freely outside walleye cages and were fed with walleye. To simulate poststocking period of fasting, walleyes were exposed to experimental treatments for 6 weeks and were deprived of food. Regardless of the prior diet, fish weight significantly declined in all treatments but no differences were found among them. Lipids declined in both dietary groups of fish; in turn, body moisture increased. Protein levels were only affected in fish fed with high-lipid diet prior to the experiment and subjected to current and predator presence. Plasma glucose gradually declined in fish fed with high-lipid diet prior to the study; whereas in the fish fed with low-lipid diet before the experiment, it remained low regardless of the treatment severity. Plasma cortisol concentrations never exceeded 30 ng ml -1 indicating no signs of acute stress during the experiment. We concluded that fish fed with diet containing higher lipid levels prior to stocking would possess better potential of withstanding adverse conditions and better survival once released to the wild.

Original languageEnglish (US)
Pages (from-to)597-603
Number of pages7
JournalPhysiology and Behavior
Issue number4-5
StatePublished - Sep 2003



  • Cortisol
  • Esox masquinongy
  • Lipids utilization
  • Muskellunge
  • Protein
  • Stizostedion vitreum
  • Walleye

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Behavioral Neuroscience

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