One researcher is developing a new explanation for this heartbreaking phenomenon. According to Moore, a member of the rescue team working on his master’s degree has found a correlation between the North Atlantic Oscillation Index, which shifts between positive and negative phases and mass stranding rates. The index affects sea surface temperature, prey distribution, and other environmental factors, and when it shifts into a negative phase and the water temperature drops, an increase in common dolphin strandings occurs the following year. A negative phase in 2011 preceded this year’s strandings. In 2013, the number of strandings of white-sided dolphins is expected to peak.
“So next year it will be interesting if this proves true, because this past year it shifted into a really negative phase,” says Moore. “I told the researcher he better get an A on this thesis because so far it’s proving true, which is interesting. But the key part is to tease out what factors are driving [this]. It’s a correlation; it’s not cause-and-effect.”
Moore hopes all the data she and her team have collected, including blood tests from live animals and necropsy results from those that didn’t survive, will shed light on what drove so many common dolphins inland last winter. The work will take months, and to help solve the mystery she’ll collaborate with other scientists, including those at the Provincetown Center for Coastal Studies, who were studying an early return of whales to Cape Cod Bay and higher water temperatures last winter. Preliminary results have shown no patterns or evidence of disease among the dolphins.
Marine mammal rescue and its accompanying data-sifting are critically important because the well-being of the dolphins is related to the health of the ocean and its impact on humans, Moore notes. What’s more, the ocean data her team gathers is shared with the National Oceanic and Atmospheric Administration, which is charged with making fishery management decisions.