New Directions in the Study of Low-Frequency Sound in Baleen

Abstract

Abstract : Integrated field research was conducted on the potential impact of man-made underwater sound on marine mammals and the functions of the low-frequency sounds of whales. This was accomplished using passive acoustics, active acoustics, tagging, vessel survey, biopsy sampling, and photo-ID. Relationships were determined between low-frequency vocal rates of individual fin (Balaenoptera physalus) whales; the identity and sex of singers; and the presence, number and distribution of animals. All singers (n = 9) were males. There were correlations between number of whales seen, level of vocal activity and number of singers. There were associations between where and when males sang, food distribution and feeding activity. Contrary to previous assumptions singers concentrated near high densities of food and sang more during periods of high feeding activity. Resultant data are important for estimating relative abundance based on passive acoustic monitoring systems and for models (e.g., AIM) used to predict acoustic impact for mitigation purposes. By placing the biologically important behavior of acoustic communication within the appropriate ecological context, hypotheses on communication functions (e.g., whale sounds are detected throughout the oceans on (USS) can be tested. This should result in a more rigorous understanding on the potential impact of human-produced LFS on large whales.