2025/01/01 by Kaitlin E Yehle, Valentina Melica, Colin J. Brauner +1 · 1 voice
Environmental Science · Agricultural and Biological Sciences · #Marine animal studies overview #Marine Bivalve and Aquaculture Studies #Aquaculture Nutrition and Growth
paper · pdf · doi:10.1093/conphys/coaf070
openalex publication_date 2025/01/01 · openalex created_date 2025/10/14 · openalex updated_date 2026/07/28
Abstract Faecal hormone metabolite (FHM) analyses are increasingly used as a non-invasive method to evaluate physiological stress in wild populations, especially those of conservation concern. In cetaceans, faecal collection from the ocean surface results in considerable variation in sample volume and density. Knowledge of the distribution of hormone metabolites within a faecal sample is limited, but is an important consideration when interpreting values. Here we investigated the variability of glucocorticoid (fGCM) and thyroid (fTHM) metabolites within fish-eating resident killer whale faeces by comparing mean concentration, standard deviation (SD) and coefficient of variation (CV) among three treatment groups: sub-samples, pooled sub-samples and homogenized pooled sub-samples from the same defecation event. No significant difference was found in the mean concentration of fGCM and fTHM across treatment groups. The mean SD for fGCM was significantly higher in sub-samples than in pooled and homogenized treatment groups (P < 0.05), while differences in the mean SD of fTHM were not significant among treatment groups. Overall, the CV of FHM measurements was reduced to less than 15% and 10%, respectively, by pooling and homogenizing the sub-samples prior to analysis. We found high correlation in fGCM and fTHM across all treatments, suggesting that values from sub-samples were generally representative of the overall faecal sample. These findings help guide methods for processing cetacean faecal samples and interpreting associated FHM data.