Ship Noise and Killer Whales
Humans live in all sorts of environments. We have traveled to every conceivable place and habitat on land, from high mountains to low valleys and deserts. The seas and oceans are also full of human activity, with boats fishing, extracting other ocean resources, and traversing large stretches of water. There is no doubt that all this activity has a direct physical impact on marine ecosystems, but less is known about the significance of the side effects of these boats. This study looks at how the noise from large ships may have an effect on large aquatic mammals, and more specifically, killer whales. Because killer whales forage through the process of echolocation, their daily activities could be seriously disrupted by foreign sounds that frighten them or alter their courses.
This study looked at a collection of data from Northern resident killer whales on the West coast of Canada, to assess and understand “typical summer time conditions in important killer whale habitats.” The researchers found that the whales exhibited “moderate” responses to the presence of large ships, but also noted that evaluating the actual effects of ship traffic was “overwhelmingly influenced by a somewhat subjective and seemingly arbitrary decision about the severity score that one uses to indicate a response.” Though the responses they noted are not an immediate concern, they were not able to find data for responses to noises higher than 150db in the studied area, which would likely alter their findings. Furthermore, they note that additional research would be useful to better understand the overall impact of ship noise on whales and other species. The cumulative impact of “repeated disturbance” may be more damaging than we realize, and bigger than the limited data set of this study can show.