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    Diets, distribution and population dynamics of Arctic cod (Boreogadus saida) in Arctic shelf ecosystems

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    Author
    Marsh, Jennifer M.
    Chair
    Mueter, Franz
    Committee
    Danielson, Seth
    Iken, Katrin
    Quinn, Terrance J. II
    Keyword
    boreogadus saida
    food
    Arctic regions
    geographical distribution
    Metadata
    Show full item record
    URI
    http://hdl.handle.net/11122/10516
    Abstract
    With climate warming and longer open-water seasons in the Arctic, there is an increased interest in shipping, oil exploration and the expansion or development of commercial fisheries. Anticipated natural and anthropogenic changes are expected to alter the Arctic shelf ecosystems, including their fish communities. As a component of the Arctic Ecosystem Integrated Survey (Arctic Eis), this project presented a unique opportunity to assess the ontogenetic, spatial and temporal variability in the distribution, abundance and trophic roles (trophic level and diet sources) of key fish species in the Chukchi Sea. For my dissertation, I addressed three objectives to advance our understanding of Arctic cod (Boreogadus saida) as a key component of Arctic ecosystems. First, I characterized the current range of variability in trophic roles within the system and explored the role of advection in shaping the fish communities' diet (isotopic signatures) with a focus on Arctic cod. Second, I examined environmental and biological influences on the distribution and abundance of Arctic cod and provided an updated stock assessment for the Chukchi Sea. Finally, I broadened the geographic scope and used available time series of survey data at the southern margin of their range in the Pacific (eastern Bering Sea) and Atlantic (Newfoundland/Labrador shelves) sectors to assess the influence of temperature, predators and competitors on their distribution. Compared to age-1+ Arctic cod, age-0 Arctic cod had a less diverse diet regardless of water mass and were limited to colder temperatures. Together, this suggests that younger Arctic cod are more vulnerable to climate change. Estimates of egg production and early survival suggest that the numbers of mature Arctic cod present in the survey area during summer are unlikely to produce the observed high abundances of age-0 Arctic cod in the Chukchi Sea. Moreover, Arctic cod distributions in their southern ranges were highly influenced by temperature and to a lesser extent by competitors and predators. When temperatures were warmer, Arctic cod occupied a smaller area. These results inform the management of Arctic cod in a rapidly changing environment and provide benchmarks against which to assess future changes.
    Description
    Dissertation (Ph.D.) University of Alaska Fairbanks, 2019
    Table of Contents
    General introduction -- Chapter 1. Ontogenetic, spatial and temporal variation in trophic level and diet of Chukchi Sea fishes -- Chapter 2. Environmental and biological influences on the distribution and population dynamics of Arctic cod (Boreogadus saida) in the US Chukchi Sea -- Chapter 3. Influences of temperature, predators and competitors on Arctic cod (Boreogadus saida) at the southern margin of their distribution -- General conclusions -- References.
    Date
    2019-05
    Type
    Dissertation
    Collections
    Fisheries

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