Evaluation of aerial surveys for assessing sardine abundance in British Columbia, 2008-2011 / by L. Flostrand and J. Schweigert. : Fs97-4/3041E

A variety of aerial survey methods were tested to detect and characterize summer Pacific Sardine (Sardinops sagax) biomass in British Columbia (BC) waters in 2008-2011. The interest to explore the feasibility of the different methods was linked to development of a United States (U.S.) aerial survey Sardine biomass index that was incorporated into the California Current Sardine population assessment in 2009. Between years, the methods deployed in BC varied by type of plane and aviation service, image recording method, survey designand spatial coverage. This report provides an overview of the methods and outcomes from the BC surveys and evaluates their effectiveness for acquiring data needed to develop indices of Sardine biomass. From evaluation of the methods tested in BC in relation to the methods deployed in the U.S., the authors conclude that the use of Compact Airborne Spectrographic Imager (CASI) technology to acquire and analyze imagery data appears to be superior to other methods if the data are collected from altitudes greater or equal to 4000 feet by a twin engine plane. However, the authors do not support aerial surveys as the most feasible option for developing an index of Sardine biomass in BC because of variable weather conditionsthat can obstruct survey efforts throughout the extensive coast, limited seasonal availability of applicable aviation services, and relatively high costs and uncertainty in the results associated with of image analyses.

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publications.gc.ca/pub?id=9.830431&sl=1

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