Thesis
Humpback Whale Abundance and Migratory Patterns in the North Pacific Ocean Assessed by means of Automated Photo-identification
Southern Cross University
Doctor of Philosophy (PhD), Southern Cross University
2025
DOI:
https://doi.org/10.25918/thesis.494
Appears in Recent Southern Cross PhD Theses
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Abstract
Following the end of commercial whaling in 1976, North Pacific humpback whale (Megaptera novaeangliae) populations showed prolonged recovery over 40 years. To better understand whale populations, this study began with development of a fully automated machine learning AI-based image recognition algorithm for matching individual identification photographs of whale flukes, reducing matching time by 98% and error rates from 6-9% to 1-3%.
This AI photo-ID system enabled creation of the largest individual marine mammal identification database to date through collaboration combining 39 separate photo-ID catalogs and community science data. The dataset documented 27,956 unique individual humpback whales in 157,350 encounters from 2001-2021, accessible through Happywhale.com. This living resource has grown to include 33,056 individuals identified from 1977-2023.
Analysis of migratory paths of whales documented in the dataset revealed that most individuals followed highly structured, consistent patterns that remained unchanged despite a multi-year marine heatwave causing severe food stress and apparent 20% mortality. While individuals occasionally diverged from expected routes, over 97% of encounters with multi-year histories occurred within defined home regions. Results suggest humpback whales are flexible with food choices but inflexible with home range selection, following largely invariant migration patterns. With climate-change-induced ecosystem shifts emerging as primary threats, conservation management must recognize that humpback whales are unlikely to relocate during food stress periods.
Using mark-recapture methods, the study estimated annual ocean-basin-wide abundance from 2002-2021. Results showed strong post-whaling recovery from 16,875 individuals (SE = 5,955) in 2002 to peak abundance of 33,488 (SE = 4,455) in 2012, followed by an apparent 20% decline to 26,662 (SE = 4,192) by 2021, suggesting the population reached carrying capacity due to environmental change-mediated prey loss. This was particularly evident for Hawaiian-wintering humpbacks, which declined 34% from 2013 peak levels by 2021, contrasting with stable Mainland Mexico breeding populations. The 2014-2016 marine heatwave, the strongest recorded globally, appeared to alter species recovery with enduring effects.
This thesis established enduring marine mammal photo-ID data management tools, ground breaking AI image recognition, and facilitated international collaborative research. These well-documented North Pacific humpback whale populations can serve as ecological indicator species in rapidly changing ocean ecosystems.
Details
- Title
- Humpback Whale Abundance and Migratory Patterns in the North Pacific Ocean Assessed by means of Automated Photo-identification
- Creators
- Ted Cheeseman
- Contributors
- Peter L Harrison (Supervisor) - Southern Cross UniversityDaniel Burns (Supervisor) - Southern Cross University
- Awarding Institution
- Southern Cross University; Doctor of Philosophy (PhD)
- Theses
- Doctor of Philosophy (PhD), Southern Cross University
- Publisher
- Southern Cross University
- Number of pages
- xix, 178
- Identifiers
- 991013291355502368
- Copyright
- © Ted Cheeseman 2025
- Academic Unit
- Faculty of Science and Engineering; School of Environment, Science and Engineering
- Resource Type
- Thesis