Document Type

Honors Thesis

Major

Wildlife Ecology

Advisor(s)

Joseph Zydlewski

Committee Members

Stephen Coghlan, Michael Kinnison, Lindsay Seward, Sharon Tisher

Graduation Year

May 2020

Publication Date

Spring 5-2020

Abstract

Alewife are a commercially, economically, and ecologically important fish, that expend large amounts of energy during their long migrations to spawning habitat. This energy demand can influence an individual’s chances of surviving and reproducing successfully. To understand how energy use may affect fitness, we captured alewife from the Souadabscook Stream over the course of their spawning migration. Fifty fish were sampled each week from May 12th to June 10th 2019. The lipid content of each individual was measured by using i) a Distell Fatmeter and ii) gravimetric analysis by measuring muscle moisture as an indirect method to assess lipid content. Population demographics such as length, mass, and sex were recorded. Otoliths and scales were used to estimate age and spawning history respectively. Fish with higher lipid content were found during the tail end of the spawning run, and tended to be smaller than those who migrated earlier. Males were also found to have more stored lipids than females. Model selection was used to test the hypotheses that i) early migrants and ii) smaller fish have elevated lipid densities. The hypothesis that demographics such as length, mass, age, sex, and spawning history differ overtime was also tested. These findings provide information regarding the bioenergetics of alewife during migration, and may inform conservation strategies.

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