Graduate Thesis Or Dissertation
 

Spatial distribution and the probability of occurrence of beluga whales (Delphinapterus leucas) in Alaskan Arctic

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  • The known distribution of beluga whales ranges from sub-Arctic to Arctic waters where they migrate in pods in response to environmental factors such as the presence of sea ice and prey. This study uses bivariate and multivariate analysis techniques to measure how environmental covariates are associated with the spatial-temporal distribution of beluga whales. Exploratory data analysis was used to determine the relationship among environmental covariates: bathymetry, slope, sea surface temperature, and distance to sea ice. Spatial analyses were used to determine the probability of occurrence of beluga whales in the northeastern Chukchi and southwestern Beaufort seas, based on each environmental covariate for the autumn months of the two study periods, from 2000 to 2006 and from 2008 to 2012. Findings from this study suggest that correlations exist between SST and distance to sea ice, and depth and distance to sea ice, and that beluga whales may prefer areas of relatively steep slope and associated increasing depth along the continental slope. Probability of occurrence maps were created for September and October for each year, based on beluga whale preference and avoidance for each environmental covariate. Areas of preference, or high probability of occurrence, had more beluga whale sightings than expected. And areas of avoidance, or low probability of occurrence, had less beluga whale sightings than expected. Model validation included randomly dividing observational data from September of 2011 into a training (70%) and testing (30%) dataset, then creating a probability of occurrence model based on the training dataset and comparing the results to the locations of the testing dataset. Outputs from the analyses can help guide studies of beluga environmental covariate preferences and the possible influences on their occurrence. Better understanding of the spatial distribution of beluga whales can provide a tool for better management practices. Improved practices in management and conservation of habitat for beluga whales will impact indigenous communities who rely on marine mammals as cultural and consumable resources.
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