Interactions between whale-watching boats and humpback whale (Megaptera novaeangliae) singing cycle in the Colombian North Pacific soundscape

Abstract

Noise in marine ecosystems has increased significantly in the last decades. One of the most significant sources is vessel traffic. This affects animals that depend on sound to interact within their ecosystems, like interrupting communication which could lead to adaptive strategies to avoid the noise. We recorded the soundscape from 0 to 15 kHz in Morro Mico and Nuqui, Colombia, from 2018 and 2019—one of the most biodiverse locations in the world, and one that has never experienced high levels of vessel traffic and has no shipping lanes. Here, humpback whale Stock G migrates to their breeding ground. The species is well-known for its songs and social calls that facilitate biological and ecological processes. One process that could shape these vocalizations is noise generated by the artisanal fishing family boats. We explored correlations between the sound energy from the humpback whale song cycle, temporal features of the song structure, other biological acoustic signals, physical acoustic cycles, and the presence of small boats. These comparisons are important because there are no large vessels (requiring AIS) that transit closely to the study area. Therefore, we focused on soundscape cycles and acoustic responses of humpback whales from purely small vessel noise.