Abstract

The western North Atlantic right whale (Eubalaena glacialis) is among the most critically endangered whales worldwide, with a current population of about 450 individuals. Because their known habitats are within 50 miles of the heavily-populated eastern U.S. coastline, these whales are subjected to multiple stressors from human-activities, and have thus been called an "Urban Whale."¹ Lack of recovery of this population has been attributed to mortalities from ship collisions and entanglement in fishing gear, along with reduced and highly variable reproductive success, which remains unexplained.² Rates of non-lethal fishing gear entanglement and ship collisions have been determined by analyzing characteristic scars on 21 body regions using all photographs of northern right whales taken from 1935–2006.³ Trends in population health have been evaluated using visual health assessment of body condition for over 200,000 right whale images taken from 1980–2002,⁴ along with a detailed analysis of skin lesions in the population.⁵ In this study, we applied these same methods to evaluate health and human impacts in a population of about 938 (95% CI = 740–1140) southern right whales⁶ (Eubalaena australis) inhabiting the remote sub-Antarctic Auckland Islands, and compared the results with those from North Atlantic right whales. In July-August 2007, over 13 days we collected photographs of 101 individual (non-calf) southern right whales. A total of 80 whales were photographed adequately to perform visual assessments of body condition, skin lesions and scarring. All southern right whales had the best possible body condition scores, whereas 16% of North Atlantic right whales overall had compromised or poor scores. Similarly, there were no visible skin lesions for the southern population, while more than 50% of northern right whales have been documented with skin lesions. None of 58 adequately photographed southern whales had any scars suggesting prior entanglements, nor was there any evidence of shipstrike or propeller scars. In contrast, in the North Atlantic, 76% of the population had entanglement scars³ and 7.4% had scars from ship collisions. In conclusion, the southern right whales showed no evidence of compromised health or the high rates of anthropogenic scarring observed in North Atlantic right whales. These results suggest that the Auckland Island right whales can serve as a valuable reference population of whales that are almost completely un-impacted by certain anthropogenic activities.

Acknowledgements

The authors are very grateful to Heather Pettis, Amy Knowlton, Philip Hamilton and Marilyn Marx of the New England Aquarium for their work documenting the visual health, scarring rates and skin lesions in North Atlantic right whales. Our thanks to Brian Skerry, Simon Childerhouse and the captain and crew of the S/V Evohe for making the Auckland Islands expedition a reality. We would like to gratefully acknowledge the funders for this project, National Geographic Society, Brian Skerry Photography, and the International Fund for Animal Welfare.

References

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