Date of Completion

2025

Document Type

Honors College Thesis

Department

Department of Biology

Thesis Type

Honors College, College of Arts and Science Honors

First Advisor

Dr. Laura May-Collado

Second Advisor

Dr. Paige Brochu

Third Advisor

Dr. Elise Lauterbur

Keywords

acoustic communication, passive acoustic monitoring, boat noise, tourism, acoustic masking, marine conservation

Abstract

This study examines the impact of boat noise on the singing activity of “Breeding Stock G” humpback whales at two locations in Costa Rica: Cuajiniquil Bay and Caño Island. Cuajiniquil is dominated by fishing boats, whereas Caño Island is dominated by tourism (e.g., whale-watching). Passive acoustic monitoring was used to collect underwater sound data at the two locations from select days in July-September of 2022, 2023, and 2024. Presence-absence of whales and boats were manually annotated, and a generalized linear model (GLM) and cumulative link model (CLM) were used to assess the relationship between whale singing activity and boat presence. The results found song activity was consistently higher at Caño Island than Cuajiniquil. Whale presence peaked in August and September at both locations, coinciding with the northern migration of BSG whales to Costa Rica during this season. Diel patterns showed song activity decreased when boats were present during the day. Boat activity had an overall stronger impact on whale singing at Caño Island than at Cuajiniquil. These findings reinforce the conclusions of previous studies that demonstrate whale singing activity declines in the presence of boat noise, especially tour boats. This study highlights the importance of acoustic monitoring in marine conservation.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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