Acoustic and visual monitoring for marine mammals at Cortez and Tanner Banks

Abstract

We have implemented continuous acoustic monitoring for baleen whales in the region surrounding Cortez and Tanner Banks, offshore of Southern California, complemented by bimonthly ship-based visual and acoustic observations. Our objective is to develop methods for acoustic monitoring of baleen whales using seafloor acoustic recording packages, the results of which will be used to produce abundance estimates. The joint acoustic and visual effort will answer questions regarding the probability for acoustic detections of individual animals, the quantitative association of calls with a particular species, and how well the number of animals in an area can be assessed acoustically. These findings can then be used to generate a detectability curve for each baleen whale species, from which the seafloor recorder data can be translated into absolute abundance estimates. The use of continuous acoustic monitoring with seafloor recording packages offers the potential for efficient and economical monitoring of marine mammals. The continuous acoustic census approach will be discussed, and compared to opportunistic visual and acoustic survey methods.