LE3 .A278 2019

2019

Stokesbury, Michael

Acadia University

Bachelor of Science

Honours

Environmental Science

Earth & Environmental Sciences

Alewife (Alosa pseudoharengus) are an anadromous species of herring that live in the Atlantic Ocean. Adult Alewife spend most of their lives in the marine environment, only travelling into freshwater lakes to spawn each year. As thousands of these fish pass upstream through rivers on their annual spawning migration, they have become a commercially valuable species for many maritime communities. Although research has been conducted on adult feeding behaviour and prey selection in both their estuarine and marine habitats, there is very little information on adult feeding behaviour in freshwater. As many larger predatory species feed on Alewife both in freshwater and at sea, whether or not Alewife are feeding at their spawning site could have large implications for nutrient transfer through trophic levels when they return to sea. In this study, I assess the evidence for Alewife feeding as well as the primary and secondary prey organisms important to freshwater Alewife diets. During the summer of 2019, 30 Alewife from the Missiguash Tide Gate and 202 from Jolicure Long Lake were sampled and dissected. Measurements of spawning stage were evaluated using gonad mass, Gonadosomatic Index (GSI), and visual spawning stage assessment. Measurements of stomach fullness were estimated using a Stomach Fullness Index (SFI). Overall, fish from the tide gate were found to be in an earlier spawning stage than fish at Jolicure Long Lake. Although all fish were found to have stomach contents, fish from the Tide Gate had a higher stomach fullness (0.015 ± 0.003) than fish at Jolicure Long Lake (0.011 ± 0.008). The primary and secondary prey species of Alewife feeding in freshwater were determined to be calanoid copepods (Calanoida spp.) and mayfly nymphs (Ephemeroptera Ephemeriidae).

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https://scholar.acadiau.ca/islandora/object/theses:3300