Identifying variables for standardization of the Northern Abalone (Haliotis kamtschatkana) Index Site Surveys time series (1978-2018) based on survey methodology and environmental variability / by Sandra...: Fs97-6/3330E-PDF

"The Northern Abalone (Haliotis kamtschatkana) is a culturally and ecologically significant endangered marine snail. This report examines forty years of data from the Northern Abalone Index Site Surveys in British Columbia. Northern Abalone densities were generally insensitive to changes in the number of surveyed index sites and quadrats. There was high imprecision around the mean estimates in both the full and restricted datasets. Inclusion of environmental variables identified with generalized additive modelling in a standardized index yielded small improvements in precision of the annual indices. Trend detection using the existing survey data is limited by the large confidence intervals around the mean densities. Recommendations are to include the full dataset in further analyses, to use a subset of environmental variables to standardize the time series, and to increase the number of index sites surveyed in future Northern Abalone surveys"--Abstract, page vi.

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