Graduation Year

2024

Date of Submission

4-2024

Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts

Department

Environment, Economics, and Politics (EEP)

Reader 1

Branwen Williams

Reader 2

Sarah Gilman

Abstract

Long-term analyses of environmental trends in the Arctic Ocean show a substantial decline in sea ice area and thickness over the last 30-40 years, affecting primary productivity and marine species abundance or distribution. Though research in the Beaufort Sea clearly shows changes in sea ice and productivity, few studies have considered the Beaufort Large Marine Ecosystem (LME), an ecologically significant area designated by the Arctic Council’s Protection for the Marine Environment that includes the Beaufort Shelf and western Canadian archipelago. We examined trends in four environmental variables (sea ice area, sea surface temperature, Mackenzie River water discharge, and chlorophyll-a concentration) over a 40-year period from 1979 to 2019 and assessed whether the annual catch of cod species and Arctic char related to environmental changes. Between the 1980s and 2010s, annual minimum sea ice coverage in the Beaufort Sea contracted by about 60%. In contrast to other studies on subregions of the Arctic Ocean, Beaufort Sea primary productivity did not increase as a function of longer open water season or larger open water areas from contracting sea ice area. Instead, open ocean chlorophyll-a varied interannually, with large spikes in 2006 and 2013. Despite one statistically significant relationship, reconstructed annual fish catch did not reflect trends in environmental variables. Coastal sea surface temperatures and chlorophyll-a concentrations exhibited slower rates of change than in the open ocean, demonstrating a need for more integrated studies across the LME. In future studies, fisheries-independent data are necessary to assess how Arctic Char and cod species respond to environmental changes in the Beaufort LME.

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