The need to consider recreational vessels in risk assessments of vessel strikes to humpback whales (Megaptera novaeangliae)

Abstract

Automatic Identification Systems (AIS) data have been beneficial in understanding spatio-temporal patterns in marine traffic to inform assessments of vessel-strike risk to large whales. However, AIS does not represent all vessel classes, particularly recreational vessels that are not legally required to use AIS. Growing evidence suggests that recreational vessels do collide with large whales, and so risk assessments relying on AIS data can underestimate the threat and misguide conservation efforts. To address this, we conducted surveys of recreational vessel and humpback whale sightings to build density surface models and estimate relative vessel-strike risk by spatial co-occurrence in an urbanized embayment, Moreton Bay, Australia. We demonstrate that 93% of recreational vessels sighted in Moreton Bay did not use AIS and that vessel strike risk varies spatially according to vessel class (recreational vs. commercial). These results highlight the importance of including recreational vessels into vessel strike risk assessments to provide a more holistic view of vessel strike.