Yellow perch genetic structure and habitat use among connected habitats in eastern Lake Michigan.

Gregory M Chorak,David J Janetski,Carl R Ruetz,Tomas O Höök,Ryan A Thum,Charlyn G Partridge,David F Clapp

doi:10.1002/ece3.5219

Abstract

Maintenance of genetic and phenotypic diversity is widely recognized as an important conservation priority, yet managers often lack basic information about spatial patterns of population structure and its relationship with habitat heterogeneity and species movement within it. To address this knowledge gap, we focused on the economically and ecologically prominent yellow perch (Perca flavescens). In the Lake Michigan basin, yellow perch reside in nearshore Lake Michigan, including drowned river mouths (DRMs)—protected, lake‐like habitats that link tributaries to Lake Michigan. The goal of this study was to examine the extent that population structure is associated with Great Lakes connected habitats (i.e., DRMs) in a mobile fish species using yellow perch as a model. Specifically, we tested whether DRMs and eastern Lake Michigan constitute distinct genetic stocks of yellow perch, and if so, whether those stocks migrate between the two connected habitats throughout the year. To do so, we genotyped yellow perch at 14 microsatellite loci collected from 10 DRMs in both deep and littoral habitats during spring, summer, and autumn and two nearshore sites in Lake Michigan (spring and autumn) during 2015–2016 and supplemented our sampling with fish collected in 2013. We found that yellow perch from littoral‐DRM habitats were genetically distinct from fish captured in nearshore Lake Michigan. Our data also suggested that Lake Michigan yellow perch likely use deep‐DRM habitats during autumn. Further, we found genetic structuring among DRMs. These patterns support hypotheses of fishery managers that yellow perch seasonally migrate to and from Lake Michigan, yet, interestingly, these fish do not appear to interbreed with littoral fish despite occupying the same DRM. We recommend that fisheries managers account for this complex population structure and movement when setting fishing regulations and assessing the effects of harvest in Lake Michigan.

Highlights

Understanding population genetic structure is crucial for conser‐ vation and management of fishes
Most fish stocks are not as easy to identify as salmonids; pop‐ ulation genetics is central for identifying cryptic stocks in the sustain‐ able management of exploited fishes
We aimed to address three questions: (a) Are Lake Michigan yellow perch genetically distinct stocks from drowned river mouths (DRMs) yellow perch? (b) If so, do yellow perch from Lake Michigan stocks use DRM habitats during any season where they may be harvested at the higher rate allowed in DRMs? and (c) Are yellow perch stocks distinct between DRM

Summary

Introduction

Understanding population genetic structure is crucial for conser‐ vation and management of fishes. Cryptic stock sorting may occur in species whose ranges span a variety of connected habitats that allow distinct stocks to reside in sympatry during different seasons or stages of the life cycle (Brenden et al, 2015; Hilborn et al, 2003; Wilson, Liskauskas, & Wozney, 2016). This is relevant to management, because unex‐ pected harvest of a specific stock can occur when the stock is har‐ vested in a location that is used seasonally and/or during a specific life stage migration. Understand‐ ing cryptic stock sorting is especially important where different stocks can reside in sympatry during seasons where harvesting occurs

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