Determining the Effects of Landlocked Alewives on Anadromous Alewife Restoration

Dam removal and fish passage projects are a critical component of anadromous alewife restoration,
reconnecting runs to prime spawning habitat in coastal lakes. However, landlocked alewife populations
have become established in many coastal New England lakes. The effects of landlocked alewives on
anadromous alewife restoration are currently unknown. This proposed research examines these effects in
Rogers Lake, Connecticut. A decade-long plan to restore anadromous alewife access to Rogers Lake was
recently completed, and the first spawning adults will have access to the lake in spring 2015. Rogers Lake
once hosted one of the largest anadromous alewife runs in Connecticut. Thus, effective restoration could
substantially bolster regional alewife production. Our specific aims are to combine juvenile density
estimates with genetic assignments to determine the abundance of anadromous alewives, landlocked
alewives, and anadromous-landlocked hybrids in the lake following restoration and to use otolith-based
aging to determine spawning time for anadromous, landlocked, and hybrid alewives to assess the effects of
spawning time overlap on rates of hybridization. We have spent two years monitoring spawning time and
genetic diversity of anadromous and landlocked alewives before restored access. For the two-year duration
of the proposed research, we will sample anadromous adults entering the lake and juvenile alewives in the
lake to monitor abundances, spawning times, and hybridization rates. The Rogers Lake restoration project
provides a unique opportunity to follow anadromous alewife recovery from its onset. This project will
provide valuable information for future restoration projects where contact between anadromous and
landlocked alewives will occur.


We have successfully restored anadromous alewife access to Rogers Lake. We have collected samples for spawn timing and genetic monitoring in 2015 and 2016. We have assessed spawn timing overlap for anadromous and landlocked alewife populations from 2013-2015. We have developed genetic markers to assess hybridization.

Expected End Date: June 30, 2018

Project Leader

Name: Eric Palkovacs

Title: Associate Professor

Organization: Department of Ecology and Evolutionary Biology

Other Principal Investigators

Name: David Post

Title: Professor

Organization: Department of Ecology and Evolutionary Biology

Name: Steve Gephard

Title: Supervising Fisheries Biologist

Organization: Connecticut Department of Energy and Environmental Protection