LE3 .A278 2018

2018

Stokesbury, Michael
Spooner, Ian

Acadia University

Master of Science

Masters

Biology

Biology

Dams are prevalent throughout North American river systems and affect river hydrology, and aquatic and terrestrial ecology. The decline in abundance of many anadromous fish species on the east coast of North America has been partially attributed to the presence of dams, and their effect on critical habitat and river connectivity. Obstruction of anadromous fish migrations has broad ecological effects, including reduced biotransport of Marine Derived Nutrients (MDN) into freshwater systems. Technical fishways have been used since the beginning of the 20th century to mitigate the effects of dams on migrating fishes. However, studies of the effectiveness and dynamics of fish passage began only recently, and most fishways remain unstudied. In this study, I assess fishway passage efficiency based on Passive Integrated Transponder (PIT) telemetry. During 2013 to 2016, from 24 April to10 June; 5,423 Alewife with a mean fork-length of 227 (± SD of 18) mm were tagged with PIT tags in three rivers on the Isthmus of Chignecto, Nova Scotia and New Brunswick, Canada. Measurements of passage and attraction efficiency were calculated for each fishway and Generalized Linear Models (GLM) were applied to determine how variables such as fish length, sex, and the number of years post-tagging were related to Alewife passage efficiency. During their year of tagging, approximately half of individuals (40 -64%) were not detected. Alewife that were detected used fishways from 16 April to 8 July. Attraction rates to fishway entrances in 2013 and 2016 ranged from 85% to 98% and fishway passage rates ranged from 0.5% to 97%. Larger individuals, males and previously tagged returnees, had higher passage success indicating that some fishways apply population-level selective pressures for size, sex and age. Alewife had greater passage in two Denil style fishways than in the single pool-and-weir style fishway. I also attempted to quantify historical MDN transfer by Alewife into lakes associated with these rivers using paleolimnological methods. One sediment core was taken from each of two lakes and was analyzed using Stable Isotope Analysis (SIA) and X-Ray Fluorescence (XRF). However, the rivers chosen for the analysis did not have historical records of fish abundance, so a baseline against which the new SIA data could be compared was not available. The methods and results presented here can be used to guide future research. Marine sediment in both cores showed a change in the concentration of S, 34S, 13C, 14N, K and Ba/Ca ratio, which could (along with other potential marine proxies such as Sr) be used to measure relative MDN input by anadromous fish. Any such projects should use similar lakes with known Alewife abundances and records of land use and alteration to effectively apply the methods presented here and determine historical input of MDN from Alewife during their spawning run.

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https://scholar.acadiau.ca/islandora/object/theses:2701