This 1991 line-transect survey was designed to make abundance estimates for the cetacean species commonly found in California waters and killed in commercial gill net fishing operations. This survey was conducted by the NOAA Southwest Fisheries Science Center aboard NOAA Ship McArthur for a total of approximately 10,000 kilometers surveyed from late July to early November 1991. This dataset provides the time-date and geographical coordinates, by species/stock, of all cetaceans detected during the survey, as well as the daily and intra-daily start and end points of the line-transect survey. Purpose The primary purpose of the cruise was to estimate the abundance and understand the distribution of dolphin and whale species that inhabit California waters and are killed in United States commercial gill net fishing operations.