NOAA EPP Summer Interns 2004

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

Karitsa WilliamsKaritsa Williams worked with Dr. Aleta Hohn (vitae) and Dr. John Hare (vitae) in 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 was 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.

Introduction to Research
Harbor Porpoise (phocoena phocoena) are the most familiar cetaceans distributed in the Northern Hemisphere. Harbor porpoise are not well understood as far as biology and ecology. They are hard to study in the wild and are also not easy to keep alive in captivity. In 1991 Harderwijk Marine Mammal Park was opened as a place where small cetaceans can adapt to sea conditions before returning to the wild. The staff kept records of techniques used and responses of the animals to their treatment. After improvement, porpoises were obtainable for research on their sensory capabilities and response to types of fishing nets.

There are several reasons that these marine mammals are interesting for study purposes. One reason is that they are one of the smallest of the cetaceans and face unusual set of problems dissimilar to most dolphins or other whales. Another reason is that their robust body shape and thick blubber layer allows them to adapt to cold water conditions. More than 40% of their body is composed of blubber and skin to keep them warm. The average size of a harbor porpoise is 2m long and because of the small size, not much energy can be stored in the animal. They have no beak or no defined pigmentation pattern. The dorsal fin is triangular and is located in the mid-body.

Harbour PorpoiseHarbor porpoise must stay close to their source of food or starve. Along the east coast of the USA, newly weaned calves appear stranded on beaches from Massachusetts to North Carolina due to not maintaining a good source of food. When calves are separated from their mother, they are faced with the challenge of survival on their own. Some are unable to feed on their own and therefore become emaciated and die. This brings us to the project in determining the relationship between sea height and sea surface temperature on strandings of harbor porpoise.

The problem in this research project was to determine what may have caused the high number of strandings during the winter of 1999 and compare it with other years ranging from a period of January to May from the years 1995-2001. Sea surface temperature (SST) and sea level data was only available for the years 1995-2001. Only one other episode of alarming numbers of stranding of harbor porpoise in North Carolina occurred in recent times and that was in 1977. Also in the year 1999, where there were a high number of stranding, a combination of oceanographic events were seen that contributed to the high number of strandings. In order to compare data of the 1970’s a literature research was required that allowed a comparison of the data collected by oceanographic sampling cruises during the 1970’s period. The goal was to use sea surface temperature (SST) and sea level data for the years when it was available to ensure that those same events did not occur in the years where high number of strandings did not occur.

This paper can be found in it's entirety at: