Characterizing movement and searching behavior of humpback whales at the North-Norwegian coast

• Main Author: Utengen, Ingvild Ytterhus
• Format: Master Thesis
• Language: English
• Published: UiT Norges arktiske universitet 2022
• Subjects: humpback whale; animal movement; Megaptera novaeangliae; Culpea harengus; satellite tracking; foraging; BIO-3950; Barents Sea; Norway; Norwegian Sea; Humpback Whale; Northern Norway
• Online Access: https://hdl.handle.net/10037/25753

Studying movement patterns of individual animals over time can give insight into how they interact with the environment and optimize their foraging strategies. Humpback whales (Megaptera novaeangliae) undertake long seasonal migrations between feeding areas in polar regions during summer/early winter and breeding areas in more tropical areas during late winter/spring. The Norwegian Sea is a part of the humpback whale migration route between the Barents Sea and their southern breeding grounds, and during the last decade several individuals have had up to a three month stop-over period around some specific fjord areas in Northern Norway. Here they feed on Norwegian spring-spawning (NSS-) herring (Culpea harengus L.) to seemingly re-fuel before continuing their southwards breeding migration. Their smaller scale movement and individual variation in behavioral patterns during this stop-over period are not well understood, including why some whales have been observed to leave the fjords and then later return within the same season. Therefore, this study used data from 12 satellite tagged humpback whales and for the first time segmented their tracks into five distinct movement modes; ranging, encamped, nomadic, roundtrip and semi-roundtrip. This was done by using a behavioral change point analysis (BCPA) to pick out homogeneous segments based on persistence velocity at relatively small scales, and then modeled the net squared displacement (NSD) over time to differentiate movement modes. This study also visually identified longer roundtrips away from the fjords that lasted several days and examined movement modes within these. The most common movement mode was ranging behavior (54%), particularly seen during the start of their southwards migration and in areas outside the fjord systems in late winter, indicating when the whales moved over larger distances in the offshore habitat. Inside the fjord systems, encamped, nomadic, round and semi-roundtrip modes were more prevalent in December-January, suggesting the whales are ...