You are here:
FORAGE FISH AND ZOOPLANKTON COMMUNITY COMPOSITION IN WESTERN LAKE SUPERIOR
Citation:
Johnson, T. B., M. Hoff, A S. Trebitz, C. Bronte, P. Brown, T D. Corry, J. Kitchell, S J. Lozano, D. M. Mason, S. Schram, D. Schreiner, AND D. Schreiner. FORAGE FISH AND ZOOPLANKTON COMMUNITY COMPOSITION IN WESTERN LAKE SUPERIOR. Presented at 44th International Conference of International Association for Great Lakes Research, Green Bay, WI, June 10-14, 2001.
Description:
We assessed the abundance, size, and species composition of the fish and zooplankton communities of western Lake Superior during 1996 and 1997. Data were analyzed for 3 ecoregions (Duluth-Superior (1), Apostle Islands (2), Minnesota coast (3) differing in lake bathymetry, phsiodochemical, and biological patterns. Zooplankton abundance was 3 times higher in ecoregions 1 and 2, where rotifers comprised 2/3 of the individuals. Copepod zooplankton taxa was similar between ecoregions. Fish abundance was correlated with zooplankton abundance. Total fish biomass was highest in the Apostle Islands region and lowest on the Minnesota coast. Lake herring, rainbow smelt, and chubs (Xoewgonus spp.) comprised over 90% of the abundance and biomass of fishes caught in midwest trawls and recorded with hydrocoustics. Fish were size-selective in their feeding, showing preference for larger taxa. Musis was more important in smelt diets, while D. sillis was more important in Lake herring stomachs. Few consistent patterns in diet differences were found between ecoregions. Growth and condition of fish does not suggest they are resource limited. We discuss the role of fish and zooplankton community composition on system production relative to other Great Lakes examples.