Impacts of ship noise on the nighttime foraging behaviors of the North Atlantic humpback whale (Megaptera novaeangliae)

• Main Author: Blair, Hannah
• Format: Text
• Language: unknown
• Published: SURFACE at Syracuse University 2015
• Subjects: anthropogenic noise; foraging; Life Sciences; Pacific; baleen whale; Humpback Whale; Megaptera novaeangliae; North Atlantic
• Online Access: https://surface.syr.edu/thesis/89; https://surface.syr.edu/cgi/viewcontent.cgi?article=1090&context=thesis

The humpback whale (Megaptera novaeangliae) is an endangered baleen whale species with a cosmopolitan distribution. The coastal habitat of this species result in significant exposure to anthropogenic noise from human activities. Previous research in the well-studied Pacific populations has demonstrated changes in calling behavior in response to noise, but noise impacts on other critical behaviors such as foraging have not yet been investigated. This study examines the impacts of ship noise on the nighttime bottom foraging behavior of humpback whales in the North Atlantic – a region with substantial human activity including high levels of noise from commercial shipping traffic. Data were collected from 2006 to 2009 in the Stellwagen Bank National Marine Sanctuary in the southern Gulf of Maine during June and July. Data included underwater behaviors and acoustic recordings of surrounding environmental noise collected using an archival tag attached to nine individual whales. Here I use series of linear mixed models to assess the effects of ship noise on eight metrics of nighttime feeding behaviors. Fixed effects included the presence versus absence of ship noise, received level of ship noise, and the before, during, or after ship noise exposure period. These variables had significant influence on three metrics: dive descent rate, ascent rate, and number of rolls indicative of feeding events. Descent rate decreased as noise level increased, while ascent rate was significantly faster in the during or after period when compared to the before period. The number of rolls significantly increased in the after exposure period, but at the greatest received levels, feeding rolls were completely absent during dives. These findings indicate that humpback whales on Stellwagen Bank show small, but significant, changes in foraging activity when exposed to ship noise. This study supports the hypothesis that environmental noise has an impact on the nighttime foraging activities of this species.