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These data show information from 16 ship-based assessment surveys by the Southwest Fisheries Science Center from 1986-2006. Predicted annual densities were smoothed into a continuous grid of density estimates for the surveyed area. Annual grids were averaged and represent the best estimate of Risso's dolphin density in Washington over the past 20 years.
Risso's dolphins are found in temperate, subtropical and tropical waters that are generally deeper than 3,300 feet and seaward of the continental shelf. They inhabit all oceans and seas and little is known of their migration patterns. NOAA's Office of Protected Resources estimates approximately 13,000-16,000 animals in the California, Oregon, and Washington stock. This species is protected under the 1972 Marine Mammal Protection Act. |