Health status of stranded gray whales (Eschrictius robustus) in Washington State using multiple indicators

Health assessments of stranded cetaceans are determined from a variety of factors including sex, age class, length, girth, and other such parameters.  Gray whales (Eschrictius robustus) frequently strand along their migration route from Baja to Arctic waters including the waters of the Pacific Northwest. Between 1977 and 2016, we compiled records for 212 stranded gray whales from Cascadia Research Collective and other stranding network members for the outer coast and inland waters of Washington State.  This large dataset provides a wide array of factors to assess body condition and health parameters of stranded gray whales.  We examined a variety of morphometric data including quantitative values (body measurements and blubber thickness), as well as more subjective data (blubber composition and appearance, and external appearance of emaciation) to evaluate body condition and health. Of the 212 whales, 140 had length and blubber thickness, the minimum we required to include them in this analysis, with smaller subsets having some of the other elements we compared. When looking at multiple factors, we found a correlation between blubber thickness and sex, age, length and girth.  There were no correlations between blubber thickness and subjective body condition, or between blubber thickness and % lipids (r-squared= 0.001).  These results demonstrate that blubber thickness is not a good indicator of nutritional condition since even emaciated animals had significant blubber layer, though it appeared dry and fibrousy and tests of lipid composition in 43 of these animals showed lipid levels of < 5 %(n=15). This study shows that body condition on stranded cetaceans, specifically gray whales, cannot be determined from just analyzing a small number of indicators (including blubber thickness), but more a larger set of morphometric parameters and relative health information combined. 


Pasi, C., J. Calambokidis, J. Huggins. Health status of stranded gray whales (Eschrictius robustus) in Washington State using multiple indicators. Abstract (Proceedings) 22nd Biennial on the Biology of Marine Mammals, Halifax, Nova Scotia, October 22-27, 2017.