This study found ample evidence of vocally active right whales, humpback whales and fin whales and the abundance of detected calls showed patterns of seasonality and inter-annual variation. While, minke whales were not detected at the frequency level of the other species, their presence was confirmed in the study area, especially in waters further offshore. Peak presence in the winter months was contrasted by low periods of presence in the summer months, and while periods of time existed when no whales were detected, the variability between seasons and years, as well as the conservative approach to our study design supports a conclusion that for any given time, there is a chance of baleen whale presence in the area. Within the study area, whales were found across the recording transect, with different species having different distributions. Only the right whale had the largest proportion of detected presence within the WEA, but all four species did have some minimum level of presence inside the WEA. Our recommendations from these temporal and spatial results are that wind energy development poses the highest risks to right whales during their peak seasonal presence from November through April. Humpback, fin and minke whales are also at highest risk during their peak seasonal occurrence in the area, however that risk is somewhat lessened by their probability of being detected further offshore from the WEA. We caution that the variability between years makes defining peak seasonal presence difficult, and the potential environmental, anthropogenic or biological drivers of this variability are poorly understood. Based on the variable low-level monthly presence during the summer offseason months, we conclude that the risk posed by wind energy development cannot be completely mitigated through seasonal planning of activities.
Baseline ambient noise for the study area revealed a very high level of background noise at low frequencies, especially in the communication bandwidth of the right whale, minke whale and humpback whales. While we still do not fully understand how the current chronic noise conditions affect the whales on a population scale, we can conclude that the addition of turbine construction and operation would not represent a large increase in ambient noise levels, due to the current high levels of noise. We recommend measures that would mitigate risks to whales from pile driving and acute noise events and caution that even modest increases in ambient noise levels within the WEA may elicit behavioral responses from whales. Therefore, the risks of noise increases are highest for right whales that have the largest distribution in the WEA, and that further studies or analyses may be warranted to understand the potential impacts from these risks. Adding additional protections such as extending speed-restricted seasonal management areas boundaries to the WEA may mitigate some of the risks.
Odontocete acoustic signals were recorded along the continental shelf at all four high-frequency transect recording sites. Given visually observed occurrence of odontocete species in this region, we determined the ROCCA was not appropriate for signal classification on the species-level in this region. The ROCCA classified most signals as species that are less common, and infrequently classified the more common species in this region.