Behavioural Response Study

LONG-TERM GOALS

The long-term goals of this project are to contribute towards the development of a science-based sonar use policy for the US Navy which reduces the risk of injury to beaked whales from mid-frequency sonar. This project will also increase our understanding of the population and behavioral ecology of beaked whales and will contribute towards the assessment of impacts of naval activities at the Atlantic Undersea Test and Evaluation Center (AUTEC).

OBJECTIVES
The over-riding objective of this effort is to provide field support for Phase I of the Behavior Response Study (BRS). Specific objectives are:

1) To work with the Marine Mammal Monitoring (M3R) program at AUTEC to visually locate cetaceans detected acoustically on the AUTEC range, with a particular focus on finding beaked whales (Family Ziphiidae).

2) To photo-identify individual animals within each group found.

3) To attach digital acoustic tags or Dtags to beaked whales and pilot whales to prepare for playback experiments and to gather baseline data on the diving behavior of these species in Tongue of the Ocean (TOTO).

4) To conduct focal follows of the tagged whale before, during and after a playback experiment.

5) To conduct aerial surveys for stranded or injured cetaceans before BRS started, following each playback and after BRS ended, as part of the BRS mitigation.

6) To provide a team from a Bahamian non-governmental organization to allow independent observation of the experiment.

RESULTS
Blainville's beaked whales were regularly sighted on the AUTEC range during BRS-07 and appear to be one of the most frequently occurring species in the Tongue of the Ocean (TOTO). The mean group size was 2.5 whales (range 1 - 6, mode 2, median 2) and all age classes were found. Short-finned pilot whales were not sighted as frequently and were found transiting through the range. They were found in much larger groups, ranging from 30 - 40 whales.

Preliminary analysis of over 2,000 identification photographs taken during BRS-07 showed that there were 30 individual Blainville's beaked whales identified by their unique scarring patterns. Although the majority of individuals were only photographed once, there were 5 whales seen twice and 5 whales seen three times. Eight whales matched to BMMRO's existing photo-identification catalogue for TOTO from 2005 and 2006. These results suggest that there is residency in the area by some whales.

Important baseline or control data were collected from 5 Dtags deployed on Blainville's beaked whales during BRS-07. These data provided a comparison with data that were recorded from the tagged whale exposed to mid-frequency active (MFA) sonar and killer whales calls during the playback experiment. The four long tag deployments also provided valuable information on the foraging behavior of Blainville's beaked whales in TOTO. These data are also extremely useful for M3R to improve software to localize individual beaked whales by echolocation clicks detected by the AUTEC hydrophone array.

IMPACT/APPLICATIONS
Mass strandings of beaked whales in several areas (e.g. Simmonds and Lopez-Juraco 1991, Frantzis 1998, Jepson et al. 2003), including the northern Bahamas (Balcomb and Claridge 2001, NOAA 2001) have correlated with international naval operations, raising concern that beaked whales are particularly vulnerable to anthropogenic noise. Findings during BRS-07 will help to address these concerns in numerous ways. In addition to learning about the behavioral response of beaked whales and pilot whales to MFA sonar and killer whale calls during the playback experiment, we have also gathered important baseline data on their diving behavior, which will help with interpreting the results as well as elucidate information on the diving physiology of beaked whales and their foraging ecology. Equally important, we have also increased our understanding of the occurrence and residency patterns of beaked whales on the AUTEC range which will help assess current mitigation on the range and contribute much needed data for environmental reviews.

Mid-frequency active sonar is regularly used during tests on the AUTEC range, including two to three 53C sonar tests annually. With resident Blainville's beaked whales utilizing the range for foraging, it is important that the Navy ensure that their current mitigation is effective. The photo-identification data collected during BRS-07, when combined with data to be collected during BRS-08, will allow us to monitor the population status of beaked whales on the range. This 2-year sampling period will allow us to estimate abundance and rates of immigration and emigration of Blainville's beaked whales in Tongue of the Ocean to more thoroughly examine residency patterns and site fidelity. The photographic data and tissue samples collected will also contribute to a population structuring study currently being conducted on a larger scale, in the Great Bahama Canyon (TOTO forms the southern branch of this submarine canyon) to assess the relationship of beaked whales in TOTO to stocks identified elsewhere in the northern Bahamas.