Using non-traditional methodology to evaluate the influence of commercial operations on Great Slave Lake Trout, Salvelinus namaycush

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Chymy, Hailey
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Multiple surveys have taken place on Great Slave Lake with the aim of collecting data on fish populations to achieve sustainable management, however, a lack of consistency and lake coverage from these investigations’ limits data useability. Misinterpretations of data collected in early research likely contributed to the collapse of the Lake Trout, Salvelinus namaycush, stocks shortly after the commercial fishery began. The limited abundance indices available for Lake Trout, further complicated by inconsistent management areas and recording methods, prevents the incorporation of all available data into a conventional stock assessment model. Therefore, CMSY++, the most recent version of the data-limited, surplus production model, CMSY, was applied to assess the status of Great Slave Lake Trout populations. The results generated in this assessment predict that Lake Trout stocks in all current commercially fished regions are overfished, with combined Lake Trout and Lake Whitefish, Coregonus clupeaformis, quotas above estimated Lake Trout maximum sustainable yields. My findings indicate Lake Trout commercial harvest in recent years has surpassed the estimated maximum sustainable yield for the stock in some management areas. Inferences from modeling catch-time series of varied lengths suggest ~50 years of catch data should be sufficient for reference point estimation for these Lake Trout populations, as longer time series did not decrease uncertainty. The management areas with the most commercial harvest (Areas IW & IE) reveal the greatest uncertainty associated with biomass estimates, suggesting more data is required to better understand the current state of the stocks and any increases to quotas should not occur until this is done. Conclusions of my research support those suggested over 50 years ago; Lake Trout and Lake Whitefish, should be managed through separate commercial quotas to achieve sustainable management for these populations.
stock assessment, fisheries, data-limited, Arctic fish