Baseline Soundscape Analysis of a Humpback Whale Breeding Ground before Port Construction in the Gulf of Tribugá

The Pacific Coast of Colombia, particularly the Gulf of Tribugá, is relatively untouched by human encroachment and is inhabited by a variety of marine species, including humpback whale stock G. The acoustic communication system of humpback whales and other vocal species relies on an individual’s ability to establish and maintain contact with conspecifics across vast and proximate distances. Current anthropogenic sound levels from tourism and artisanal fishing activities that support the livelihood of local communities are low. If pending construction of a new international port materializes, however, a significant increase in industrial and commercial maritime traffic could occur, (1) disrupting natural sound cycles and (2) masking critical communication space. As preparation for this construction project, passive acoustic monitoring devices (Ecological Acoustic Recorders (EARs)) were deployed in the Gulf of Tribugá from September to November, 2018, and from July to September, 2019, to collect baseline data that will be presented in two ways. First, hourly power spectral density (PSD) percentiles and manually classified acoustic presence of various sound sources will be shown as overlaid time series plots. This will create a visualization tool to understand current cycles of the Gulf’s ambient acoustic environment for comparison with any changes that could result from future port construction and operation. Second, plan view maps of the ranges over which each sound source can travel at varying locations in the Gulf will be presented. Plan view maps were created by extracting acoustic features of sound sources in the EAR data and modeling three-dimensional propagation with in-house parabolic equation (Peregrine) software. These baseline levels of sound cycles and propagation potentials in the Gulf will be discussed as the first part of a Before-After Control-Impact (BACI) marine study. This project is endorsed by the International Quiet Ocean Experiment.