DOES INTENSE SHIP NOISE DISRUPT FORAGING IN DEEP‐DIVING CUVIER'S BEAKED WHALES ( ZIPHIUS CAVIROSTRIS )?

While the auditory systems of cetaceans have evolved to cope with fluctuating noise levels from natural sources, there is a growing concern that underwater noise from some anthropogenic activities may disrupt their behavior or impair their hearing (Richardson et al. 1995). Beaked whales may have a particular susceptibility to the harmful effects of noise as certain species strand in conjunction with naval maneuvers (Simmonds and Lopez-Jurado 1991, Frantzis 1998, Balcomb and Claridge 2001, Jepson et al. 2003, Martı́n et al. 2003) at least some of which have been documented to involve the use of mid-frequency sonar used to detect submarines (Evans and England 2001, Zimmer 2003). There is, however, little published information on how species of beaked whales may be affected by other anthropogenic noise sources (Malakoff 2002). Concern about the impact of noise from motorized shipping has traditionally been focused on baleen whales, due to their use of sound at low frequencies that overlap with the main frequency band of shipping noise (Payne and Webb 1971, Richardson et al. 1995). Shipping is probably the main overall source of man-made noise in the marine environment (NRC 1994, 2003), and ambient noise levels at frequencies below 100 Hz in the deep ocean have increased by an estimated 15 dB since 1950 due to motorized shipping (Ross 1987, 1993; Mazzuca 2001; Andrew et al. 2002). While most ship noise is low frequency, Arveson and Venditis (2000) describe noise from a modern cargo ship traveling at 16 kn with third-octave source levels (SLs) over 150 dB rms re 1 Pa at 1 m at 30 kHz. Noise this high in frequency has the potential to interfere with the vocalizations of many toothed whale species. Broadband cavitation noise is a major component of the noise from fast-moving ships and this