Dolphin 1258 feeds on a sea robin in Sarasota Bay in June 2026.
Advancing quantitative fatty acid signature analysis (QFASA) for cetacean diet estimation: Methodological evaluation and ecological application
Ph.D. abstract by Theresa-Anne Marie Tatom-Naecker
Quantifying cetacean diet is critical for understanding ecological and physiological processes but remains inherently challenging.
Quantitative fatty acid signature analysis (QFASA) is a diet determination method with the potential to generate detailed, long-term diet estimates, but its use in cetaceans has been limited. My dissertation presents the first application of QFASA in bottlenose dolphins (Tursiops truncatus, hereafter “dolphins”). It addresses key impediments to QFASA’s broader application in cetaceans, evaluates its performance in professional-care 
and free-ranging dolphins, compares it to other diet determination methods, and explores the estimates’ ecological implications.
In Chapter 1, I used dolphins under professional care with known diets to derive calibration coefficients (CCs) and explore the temporal integration of blubber fatty acids. I found that dolphin-and blubber layer specific CCs produced lower-error estimates and identified major prey more accurately than non-dolphin CCs, and reflected prey consumption integrated over weeks to months. I also assessed how different model configurations impacted model performance and estimate accuracy, using professional-care dolphins in Chapter 1 and free-ranging dolphins in Chapter 2. While performance and estimates were sensitive to model configuration, the dietary suite of fatty acids and inner blubber yielded better-performing, more consistent results. In Chapter 2, prey distinctiveness and bootstrap uncertainty sometimes resulted in multiple plausible estimates, but the variation typically involved redistribution among trophically similar prey, suggesting that broader dietary patterns were robust for interpretation.
In Chapter 3, I estimated free-ranging dolphin diet using QFASA and stable isotope analyses to compare the methods and evaluate contemporary diets relative to historical studies. QFASA provided finer taxonomic resolution than stable isotopes but greater variability and uncertainty. However, both methods converged on broad dietary patterns, suggesting that dolphins selectively consumed a subset of available prey and exhibited modest individual- and demographic-level variation. Comparisons with previous studies suggested contemporary shifts in dominant prey that likely reflect both methodological differences and environmental changes.
Together, these studies demonstrate that QFASA can successfully provide detailed, long-term diet estimates and valuable ecological insights for dolphins. However, careful model configuration selection and interpretation of uncertainty are essential, and QFASA is most powerful when applied alongside other diet determination methods.
