Morgan Pirozzi

The effects of vessel noise on humpback whales in proximity to Chesapeake Bay shipping lanes

Abstract
Instances of humpback whale (Megaptera novaeangliae) mortality have been increasing in recent years along the United States East coast, with higher concentrations occurring in the Mid-Atlantic region. An Unusual Mortality Event was declared by NOAA Fisheries and their investigations found around half of the animals died as a result of human interaction (NOAA Fisheries 2021). Ship strikes in particular have proven to be an ongoing crisis in the humpback population, particularly in areas with high vessel traffic. In the Chesapeake Bay, dredged shipping channels are places of potential substantial interaction between foraging humpbacks and approaching vessels. Digital acoustic tags (DTAGs) were deployed on humpback whales off the coast of Virginia Beach at the mouth of the Chesapeake Bay to collect data on animal behavior in response to ships, including the intensity of received vessel noise and foraging lunge behavior, but not in conjunction with satellite tracking. It was hypothesized that a predictive model might be established between acoustic data received by the tags and vessel distance, which could be used to determine close approaches between the vessel and the animal without a focal follow. Although there is a trend of decreasing vessel noise with distance, there is considerable variation, and the linear relationship is not strong enough to establish an accurate predictive pattern. Additional analysis on the effect of close vessel approaches on humpback whale feeding behavior in the vessel lanes was also conducted, which indicated that current interactions with vessel traffic might be disrupting the humpback’s foraging behavior. In the future, further modelling refinements will hopefully add stability to modeling efforts and allow for a more robust assessment of humpback behavior in response to ship approaches.

Avery West

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