The ever changing prey of lake trout in Lake Michigan

J.L. Jonas, C.R. Bronte, S.J. Czesny, A. Happel, M.S. Kornis, J. Rinchard, S. Schaick

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

A rapidly changing forage base in Lake Michigan, precipitated by invasive species, has complicated our understanding of foraging patterns for native lake trout. We evaluated spring diet observations from 1996-2016 gill net surveys in Michigan waters (MIDNR) and summer diet assessments from 2015 angler catches lake-wide (USFWS/INHS) to explore spatial and temporal patterns. Spring lake trout diets in Michigan waters were comprised primarily of pelagic species like alewife, rainbow smelt, and bloater prior to 2002, after which round goby began to play an increasingly important role. Increased reliance on round goby was first observed in southern Lake Michigan, followed by the north when in 2012 gobies began to compose a large portion of the diet. By contrast, diets in angler harvested fish from May - August 2015 indicated a higher proportion of alewife in lake trout diets than in those captured in spring gill nets, both in Michigan waters and lakewide. Fatty acid signatures were assessed on from subsets of fish collected in both efforts which suggest spatial segregation in lake trout diets. We suggest the influence of season (goby migrations), location and collection method (benthic gillnets vs. pelagic angling) are important when interpreting diet information and assessing the relative importance of species like round goby.
Original languageEnglish (US)
Title of host publicationFrom Cities to Farms: Shaping Great Lakes Ecosystems
Pages191-192
StatePublished - 2017

Keywords

  • INHS

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