Passive Acoustic Beaked Whale Monitoring Survey of the Channel Islands, California.

摘要

Beaked whales (family Ziphiidae) are a poorly understood group of cetaceans, known for their deep diving capabilities. Recently, interest in beaked whales has increased due in part to well publicized stranding events associated with military sonar exercises (Johnson et al., 2004). Mass strandings of beaked whales were first linked to Naval sonar exercises in the Canary Islands (Simonds and Lopez- Jurado, 1991). Pathological examinations of the heads of stranded whales following naval maneuvers in the Bahamas (Balcomb and Claridge 2001) and the Canary Islands (Jepson et al. 2003) confirmed the existence of lesions. Although the exact causal factors resulting in these stranding events remains unclear, it has been hypothesized that an acoustically induced, maladaptive behavioral flight response that elicits long bouts of shallow dives above lung compression depth could result in gas bubble formation and ultimately stranding (Cox et al. 2006; Falcone et al., 2009). Beaked whales spend the majority of their time at depth and are relatively inconspicuous at the surface of the water. As such, they are difficult to detect using standard visual survey methods. Visual surveys are further constrained by poor weather and light conditions. This has resulted in difficulty in gathering basic abundance and distribution information about these animals in the field. The lack of information regarding abundance and distribution of beaked whale species impedes the ability of researchers to accurately characterize and define beaked whale habitat. This in turn limits the researchers capacity to effectively inform policy makers and resource managers about conservation, management and mitigation measures for these species.