Singing patterns of humpback whales (Megaptera novaeangliae) in wintering grounds off the coast of Central America and potential negative effects of tour boat traffic

• Main Authors: Ziegler, Kate, Rosten, Shelby, Mcaree, Danielle
• Format: Text
• Language: unknown
• Published: UVM ScholarWorks 2019
• Subjects: Pacific; Humpback Whale; Megaptera novaeangliae
• Online Access: https://scholarworks.uvm.edu/src/2019/program/68

The waters off of the Pacific coast of Central America are important wintering grounds for humpback whales migrating from the Northern and Southern Hemispheres. Predictable humpback presence in these tropical areas has sparked a growing whale-watching industry, generating concerns surrounding potential communication masking from boat noise. This study investigates the daily song occurrence of humpback whales and the impact of low-frequency engine noise on those patterns. Passive acoustic monitoring was used to record activity of whales and boats in one wintering ground of Costa Rica, Isla del Cano, and two areas in Panama: Coiba National Park and Islas Secas between September and November 2016 and 2017, respectively. These recordings were also used for a preliminary analysis of the sonic structure of the songs, tracking any discrepancies between different populations and changes over time. Humpback whale singing activity and boat detections were higher in Costa Rica than in the Panama. In Costa Rica, male humpbacks sang throughout the day with a decrease during mid-day hours. This decrease in singing activity between 8 a.m. and 4 p.m. was correlated with an increase in boat activity. In contrast, humpback whales off the coast of Panama showed more variability in their singing patterns and did not appear to be influenced by boat presence. The discrepancies in humpback singing patterns may be attributed to the designation of Coiba and Secas as transit areas or female nursing grounds rather than singing grounds for the males. Differences could also be due to the time of the year in which the data was collected. Our study provides the first assessment of humpback whale singing activity for both countries, which can aid in informing conservation and management decisions.