Prey consumption by the burbot (<i>Lota lota</i>) population in Green Bay, Lake Michigan, based on a bioenergetics model

Abstract

We estimated prey consumption by burbot (Lota lota) based on diet, mortality, growth, maturity, thermal history, population density and a bioenergetics model derived for a similar, cold-water gadoid, the Atlantic cod (Gadus morhua). In Green Bay, Lake Michigan, burbot &gt;400 mm fed primarily on fish; smaller burbot probably fed mostly on invertebrates and sculpins (Cottus sp.). Our calculations indicate that burbot of age ≥1 consumed 16 kg/ha of prey (12.2 kg/ha of fish) in 1988 in the Wisconsin waters of Green Bay including 3.3, 2.1, 1.9, 1.2, and 0.8 kg/ha of rainbow smelt (Osmerus mordax), sculpins, alewife (Alosa pseudoharengus), yellow perch (Perca flavescens), and bloater (Coregnus hoyi), respectively. On an areal basis, piscivory by burbot in Green Bay was higher than the reported lake-wide average for consumption by all salmonids in Lake Michigan. Burbot consumed about 25% of the lake-wide salmonid consumption of alewife per unit area and close to the estimated combined commercial and sport harvest of yellow perch in the Bay the same year (271 vs. 325 tons). Thus, burbot should be included when considering the balance between predatory demand and forage fish production in Green Bay and probably also in other areas of Lake Michigan.