A Bioenergetics Model for Analysis of Food Consumption Patterns of Bloater in Lake Michigan

Abstract

We developed a bioenergetics model for bloater Coregonus hoyi based on a synthesis of studies on the energetics of bloater and other coregonines. This model was applied to the Lake Michigan population with information on water content, gonad weight, energy density, diet, and thermal history. Water content (inversely correlated with energy density) of nonspawning Lake Michigan bloaters decreased linearly with increasing weight for fish smaller than 155 g. Model results indicated comparatively small seasonal changes in consumption, a result of high consumption by bloaters at low temperatures and relatively small differences in the temperatures of occupied water between winter and summer. Growth rates and food conversion efficiencies of bloater estimated from the model were higher by factors of 2–4 than comparable values for the alewife Alosa pseudoharengus, indicating that Lake Michigan could support a higher biomass of native coregonines than of the introduced alewife. Bioenergetics estimates of annual consumption of Diporeia hoyi and Mysis relicta by both bloaters and alewives more than doubled between 1973–1975, when alewife dominated, and 1987, when bloater dominated. This increase was most evident in the winter, when bloater feeding rates were relatively high, and during summer, when alewives fed primarily on zooplankton.