The dependence of target strength of the northern right whale (Eubalaena glacialis) on the acoustic properties of blubber

Whale detection and tracking using active sonar is a subject of recent study [J. H. Miller, D. C. Potter, T. Weber, and J. Felix, J. Acoust. Soc. Am. 105, 992 (1999)]. In that previous work, the measured target strength of a northern right whale (Eubalaena glacialis) was found to be less than that measured for a humpback whale (Megaptera novaeangliae) of the same size and aspect (about 0 and 5 dB, respectively). The difference was explained by modeling the thicker blubber of the right whale as a lossy layer in a plane wave reflection coefficient. However, values for the acoustic properties of the blubber were estimated from tissue properties of other mammals [R. C. Chivers and R. J. Parry, J. Acoust. Soc. Am. 63 (1978)]. In April, 1999, a 60‐ton northern right whale named Staccato was found dead near Cape Cod. Blubber samples were acquired by the National Marine Fisheries Service and acoustic properties determined using a multi‐sensor core logger in URI Marine Geomechanics Laboratory. Sound speed and density data have been used to refine the plane wave reflection coefficient model and corroborate the earlier work. [Work supported by NMFS.]