Round Goby Abundance in Lake Huron: An Exploratory Modeling Approach Based on Predator Consumption

Session: Exploring Predator-Prey Dynamics and Feeding Ecology in the Great Lakes (2)

Norine Dobiesz, Michigan State University, Dept. of Fisheries & Wildlife, [email protected]
James Bence, Michigan State University, Dept. of Fisheries & Wildlife, [email protected]
Jixiang He, Michigan Department of Natural Resources, Lake Huron Research Station, [email protected]
Charles Madenjian, U.S. Geological Survey, Great Lakes Science Center, [email protected]

Abstract

The Lake Huron’s prey fish community underwent substantial changes during the 1990s and 2000s, including the range expansion of non-native round gobies and a dramatic decline in alewife abundance and biomass.  Diet studies show that lake trout and walleye increased consumption of rainbow smelt and added round goby to make up for alewife declines.  Changes to the benthic community resulted in increased piscivory by lake whitefish, with round gobies exceeding 35% of their diet after 2007.  We adjusted recruitment in an age-structured population model for round gobies to match external estimates of round goby consumption by predators from coupled age-structured population and bioenergetics models (estimated consumption during 2008 and 2010 was 23 kilotonnes (kt)).  We calculated, under different assumptions, that between 648 and 1, 915 billion age-0 round gobies are required to produce a population of sufficient size to support the mean consumption of gobies by the key predators in Lake Huron.  Model estimates of population biomass of age-1 and older round gobies in the main basin of Lake Huron ranged between 32 and 185 kt, which are more than an order of magnitude higher than the peak bottom trawl "swept-area" estimate on record for Lake Huron’s main basin.