LE3 .A278 2021

2021

Stokesbury, Michael

Acadia University

Bachelor of Science

Honours

Biology

Biology

Alewife (Alosa pseudoharengus) is an anadromous fish that spawn between late April-July in freshwater lakes in the Isthmus of Chignecto, NB, Canada. Alewife populations support both recreational and commercial fisheries for food and bait fisheries. These fish are major vectors of marine derived nutrients into coastal freshwater systems. Rivers within the Isthmus of Chignecto have been heavily influenced by the construction of culverts dams, and tide gates which may delay or impede the movements of alewives. Differential success in navigating barriers has the potential to bias upstream sex ratios in preferred spawning grounds. Using data collected during tagging and sampling activities between 2016-2019 from estuarine sites (n=3658), freshwater riverine sites (n=914), and a known spawning site (n=201) were used to document sex ratios. The spawning run was split into early (April 24 -15 May), mid (16 May -6 June,), and late (7 June -28 June) periods, including all fish captured in each year. Male to female sex ratios in estuary study sites were not significantly different (ANOVA, p>0.05). Sex ratios at estuarine sites did not differ significantly during the early, mid and late periods (ANOVA, p>0.05). A general linear model with binomial distribution was used to examine if the probability of passage success through three fishways as a function of sex, total length, returnees, and site. It was found that with increasing total length, fish passage increased significantly. Returnees also differed significantly from first time spawners and were more successful in passing the fishways which was also found by Nau et al (2017) in the Isthmus of Chignecto between 2013 –2016. Sex was not a significant factor in determining passage success. However, trends show that males are better at passing tide gates than females. This is likely due to the relative muscle of males compared to females. Future research should focus on the analysis of telemetry data at tide gates and antenna array sites throughout the river to identify sources of potential sex bias.

The author retains copyright in this thesis. Any substantial copying or any other actions that exceed fair dealing or other exceptions in the Copyright Act require the permission of the author.

https://scholar.acadiau.ca/islandora/object/theses:3595