Christopher Newport University bottlenose dolphin sightings in Virginia estuaries 2000-2006

Original provider:
Andrew DiMatteo, US Navy

Dataset credits:
Kevin Foss, Christopher Newport University;
U.S. Department of the Navy

Abstract:
The Elizabeth River is bounded almost totally by industrial, urban, suburban, commercial shipping and military facilities. Tidal in nature, the river has low flow, resulting in heavy contamination loads. The population studied is the Northern Migratory Stock of the US Atlantic coast, appearing in this area from May through November. Standard small boat, focal group follow, passive observation techniques were used, along with photography of individuals. Data on location, group size estimates, activities observed and relevant environmental observations were recorded every five minutes. The dolphins appear as individuals or pairs in April and May, with group size increasing in June to a peak mean of 29 animals sighted per encounter. Group size then decreases in October and November. Probability of encountering dolphins ranges from 0% during the winter and early spring to over 80% in July, tapering off towards fall. Activity patterns show greatest diversity in July and August, with travel constituting the main activity early and late. Despite a peak of births in the area in May-June, there is little mating until July, with the incidence of sexual activity peaking in September.