Using new tag attachments to study humpback whale fine-scale spatiotemporal dive behavior, habitat use, and reaction to ships off Northern California

• Main Author: Szesciorka, Angela R.
• Format: Text
• Language: unknown
• Published: SJSU ScholarWorks 2015
• Subjects: biologging; dive behavior; foraging behavior; habitat use; ship strike; whales; Ecology; Animal behavior; Conservation biology; Balaenoptera musculus; Humpback Whale; Megaptera novaeangliae
• Online Access: https://scholarworks.sjsu.edu/etd_theses/4560; https://doi.org/10.31979/etd.r4u6-dkau; https://scholarworks.sjsu.edu/context/etd_theses/article/8107/viewcontent/Szescior.PDF; https://scholarworks.sjsu.edu/context/etd_theses/article/8107/filename/0/type/additional/viewcontent/Szesciorka_Angela_thesis_supplementary_files.docx

Understanding the foraging behavior of humpback whales (Megaptera novaeangliae) is important for ethology and monitoring ecosystem-level health. Because humpback whales are generalist foragers, regional dive differences should reveal information about prey preference and availability. Any external influences of foraging behavior has important conservation implications because disruptions to foraging may impact individual fitness. From 2013 to 2014, I opportunistically tagged 22 humpback whales and 12 blue whales (Balaenoptera musculus) to test eight tag attachments, which were used to study the fine-scale dive behavior of humpback whales in four regions off California, and when they encountered ships. Four-barb tag configurations remained on the longest with no difference in reaction and no infection; however, some breakage occurred. Whales in Bodega Canyon and on the continental break/slope made deeper, longer foraging dives to feed on krill, while whales in Monterey Bay and on the continental shelf foraged in shallow waters on more fish species. Encounters between ships and whales showed changes to overall dive behavior depending on dive type, but responses varied. Whales, mostly juveniles and injured whales, were more at risk in the upper 50 m of the water column during the daytime. This study provided insight into how humpback whale dive behavior differenced among regions and how ship encounters affected dive behavior.