Date of Award

Winter 2025

Project Type

Thesis

Program or Major

Oceanography

Degree Name

Master of Science

First Advisor

Jennifer L Miksis-Olds

Second Advisor

S. Bruce Martin

Third Advisor

Elizabeth L Harvey

Abstract

Sei whales are difficult to visually monitor due to their cryptic presence and lack of breaching. Passive acoustic monitoring has the potential to expand knowledge of sei whale movement ecology. The present study characterizes sei whale movement patterns related to migration dynamics in the Gulf of Maine. Five bottom-mounted Acoustic Long-Term Observatory landers, each equipped with a tetrahedral array of omni-directional hydrophones, were deployed throughout the Gulf of Maine as part of the Acoustic and Environmental Observation Network (AEON) in the Northwest Atlantic project. A combination of manual and automated detections was used to assess sei whale daily and seasonal vocal presence. Horizontal bearing estimation of detected vocalizations was used to examine sei whale directional movement patterns among sites. Daily abundance was estimated per site and throughout the AEON network through the absolute minimum number method. Results suggested strong peaks in vocal presence in each spring and fall from the years of 2021-2024. Bearing estimation resulted in a hot spot of sei whale presence being identified near the Northern Edge of Georges Bank where they returned every spring and fall from 2021-2024. The greatest abundance per day was identified to be seven sei whales between April 29 and May 1, 2023, and on October 10, 2023. The peak abundance of seven sei whales corresponded to a monthly density estimation of 0.022, 0.078, 0.37 animals/100 km2 under NL 10, NL 50 and NL 90 conditions, respectively. These results provide the first acoustic estimate of sei whale abundance in the Gulf of Maine, further informing mitigation and management strategies.

Download

Share

COinS