IMIS

This study was conducted by the NOAA Southwest Fisheries Science Center primarily in the southern Gulf of California aboard NOAA research ship McArthur from early September to early November 1995 for a total of approximately 6,000 kilometers surveyed. The project focused on two potential approaches to improve abundance estimates of long-diving whales: (1) acoustic detection of diving animals, and (2) collecting dive interval data on those species to serve as a basis for a model-based abundance correction factor. 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 this research was to learn how to better estimate the abundance of long-diving whales during ship line-transect surveys. These whale species, including beaked whales and dwarf and pygmy sperm whales, dive for such long periods of time that there is a high probability that they will never surface within the visual range of observers searching from a moving survey vessel with 25X binoculars.