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Thursday, May 15, 2014

Why can't we save stranded dolphins?

It’s tragic when whales and dolphins strand themselves on beaches. It becomes even more sad when, despite heroic efforts by teams of veterinarians and volunteers, the animals still don’t survive. Why do some dolphins swim away and others restrand themselves and die?

To find out, scientists led by Sarah Sharp of the International Fund for Animal Welfare (IFAW) and Tufts Cummings School of Veterinary Medicine and her colleagues analyzed data from stranded common dolphins. Common dolphin strandings are unfortunately common at Cape Cod, Massachusetts where the research was conducted. During a 2 year period, the researchers responded to 143 stranded common dolphins where the animal was still alive.

Upon arriving on the scene, IFAW vets took measurements and blood samples and performed physical examinations while quickly preparing the animal for transport to a suitable release site. All dolphins were released the same day they were found. A subset of these were tagged for satellite tracking. Dolphins that were still swimming around after three weeks were considered ‘survived’. Dolphins that died during the initial response effort (but after blood drawing) or that restranded themselves or were found dead within that 3 week period were considered ‘failed’.

The researchers found blood chemistry differences between the survived and failed groups. Anemia was a very strong indicator that the animal would not survive. Failed dolphins also tended to have cardiovascular abnormalities, pneumonia or liver disease. There were also differences in length to girth ratio in surviving versus failing dolphins.

All of this suggests that by the time a dolphin strands himself on a beach, he's probably beyond saving. In many cases, nothing can be done for him. There are animals that do survive, however, and identifying them is critical, especially during mass strandings, when responders must quickly decide which animals to save first and which to euthanize. The data collected by Sharp and her colleagues could become valuable triage tools for managing marine mammals.

Sharp, S., Knoll, J., Moore, M., Moore, K., Harry, C., Hoppe, J., Niemeyer, M., Robinson, I., Rose, K., Brian Sharp, W., & Rotstein, D. (2013). Hematological, biochemical, and morphological parameters as prognostic indicators for stranded common dolphins ( from Cape Cod, Massachusetts, U.S.A. Marine Mammal Science DOI: 10.1111/mms.12093.