Eavesdropping on whales: working on the challenges of estimating cetacean abundance using passive acoustic data
Speaker: Danielle Harris (CREEM)
Acoustic data are increasingly being used to infer cetacean abundance or density. Recordings of the vocalisations of many species are being collected from both dedicated and opportunistic surveys. In some circumstances, standard abundance estimation methods can be used to analyse the acoustic data. However, abundance estimation methods may need to be adapted or novel methods created, especially for use with opportunistic datasets. In this seminar, I aim to (a) give a general overview of abundance estimation using passive acoustic data and (b) highlight some of the current research areas by focusing on two specific examples. The first example involves adapting distance sampling methodology to deal with marine mammals at depth. The motivation for this work came from two sources: monitoring deep diving beaked whales using acoustic equipment towed by ships, and a recently completed project that investigated the potential to monitor fin whales using Ocean Bottom Seismometers. The second example involves the development of an abundance estimation approach where only the direction to a calling animal is known. This work is part of a new project that is utilising the Comprehensive Nuclear Test Ban Treaty network of instruments (primarily designed to detect nuclear weapons testing) to monitor blue and fin whales.