FY 1999

Passive acoustic methods applied to fin whale population density estimation

McDonald, M.A., and C.G. Fox

J. Acoust. Soc. Am., 105(5), doi: 10.1121/1.426880, 2643–2651 (1999)

Assessing the size of cetacean populations in the open ocean has traditionally relied on visual surveys alone. The addition of acoustic monitoring can complement these surveys if reliable protocols can be formulated and calibrated with visual techniques. A study is presented to estimate fin whale population statistics based on near-continuous recording from a single hydrophone. Range to calling animals is estimated by transmission loss and multipath methods to provide a minimum population density estimate. Results are derived from recordings at a hydrophone site north of Oahu, Hawaii that have been the focus of earlier studies. The average calling whale density is 0.027 animals/1000 km², while the seasonal maximum calling whale density is about three times the average, or 0.081 animals/1000 km². Over 30 fixed hydrophone sites are available around the world's oceans from which such statistics could be generated.