Diet and Digestion Rates of Slimy Sculpin, Cottus cognatus, in an Alaskan Arctic Lake

Authors:
  • AHAnne E. Hershey
    Anne E. Hershey
  • MMMichael E. McDonald
    Michael E. McDonald
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Abstract
In arctic Toolik Lake, slimy sculpin (Cottus cognatus) rely on a diet of larval chironomids (Diptera: Chironomidae). Dry weight of sculpin gut contents was not correlated with fish wet weight. This finding, combined with age and growth data, suggested that sculpin may be food limited in Toolik Lake, particularly as they approach reproductive size. Since three taxonomically distinct chironomids were digested at similar rates, one chironomid species was used as a marker to measure gut passage. Gut passage rate as a function of temperature fits an inverse quadratic model slightly better than a negative exponential model. Sculpins took approximately 1 d to digest food at typical summer temperatures (8–16 °C), but approximately 2 d at a typical winter temperature (4 °C). Since winter is three times longer than summer, winter feeding by sculpins may have greater impact on chironomid density than summer feeding. If sculpin are important in the diet of other Toolik Lake fishes, they may serve as an important trophic link between benthic and pelagic production.

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