Models of cargo vessel strike risk on the United States East Coast from 2009-2024 highlight increasing and shifting anthropogenic threats to humpback whales

Accounting for changes to vessel strike risk is essential for effective management of large whales. Elevated strandings of humpback whales ( Megaptera novaeangliae ) along the East Coast of the United States has led to growing public concern and prompted the declaration of an unusual mortality event (UME) in 2016, associated with vessel strikes. Here we model risk of vessel strike for humpback whales throughout the U.S. East Coast from 2009 to 2024, encapsulating periods before and during the ongoing UME. We incorporate vessel density from publicly available cargo vessel Automatic Identification System (AIS) data and humpback whale density models adjusted for population growth to assess temporal changes in risk. Cargo vessel strike risk increased from 2009 to 2024 near all five ports examined, and the Port of New York & New Jersey exhibited the greatest increase in risk due to increases in vessel traffic. Increases in vessel size also contributed to higher risk. Spatial analyses identified New York/New Jersey and Mid-Atlantic regions as hotspots of risk during the UME. Elevated risk in these hotspots, which show comparatively low humpback whale densities, was driven by high vessel density and was highest from fall through spring. Massachusetts showed high vessel strike risk from spring through early fall driven by high whale densities. These vessel strike risk assessments broadly align with recent stranding patterns due to vessel strike. Our results demonstrate how shipping traffic changes in key ports can drive change in vessel strike risk, and highlight how models can aid management strategies to reduce vessel strike risk.