The Relationship between Sea Height and Sea Surface Temperature on Strandings of Harbor Porpoise along the North Carolina Coast

Interns for the summer of 2004 assisted with determining whether an unusually high number of strandings of harbor porpoise during the winter of 1999 was due to an unusual juxtaposition of oceanographic features in the western the mid-Atlantic. The goal were to investigate whether a narrow band of cold water near shore followed by a strong warm water front results in higher numbers of stranded harbor porpoise than when the front is further offshore. This question has been a concern because an alternative explanation for unusually high numbers of strandings is entanglement of porpoises in gillnets along the mid-Atlantic coast. The interns worked on compiling extracted sea surface temperature (SST) and sea level data, created graphs and GIS plots, and assisted with analysis of the data. Only one other episode of alarming numbers of strandings of harbor porpoise in North Carolina has occurred in recent times and that was in 1977. Interns used SST and sea level data for years when it was available to ensure that the convergence of oceanographic events seen in 1999 did not occur in other years when high numbers of strandings also did not occur. Although comparable data do not exist for the 1970’s, oceanographic sampling cruises did collect data that may be useful. Access to these results required a literature search.