You are here:
INFLUENCE OF TURBIDITY ON FISH ABUNDANCE IN WESTERN LAKE SUPERIOR
Citation:
Swenson, W. INFLUENCE OF TURBIDITY ON FISH ABUNDANCE IN WESTERN LAKE SUPERIOR. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/3-78/067.
Description:
This research project was developed to improve understanding of the influence of turbidity on fish populations and the mechanism through which its effects are induced. Field and laboratory studies emphasized measurement of behavioral response of fish and resulting changes in fish species interrelationships in western Lake Superior. Direct effects of red clay turbidity on survival and growth of larval lake herring (Coregonus artedii) were also measured. Field measurements demonstrated that light penetration in western Lake Superior is reduced significantly even at very low levels of red clay turbidity. Zooplankton and fish abundance and distribution were influenced by turbidity. Zooplankton abundance and distribution was highest near the surface in red clay plumes. Smelt (Osmerus mordax) move into the upper 12 m of water in response to turbidity where their predation on larval fish increases. Predation by smelt on larval lake herring was identified as a potentially important factor contributing to the decline of the formerly abundant western Lake Superior lake herring population and the commercial fishery which depended upon it.