The abundance of coastal morphotype bottlenose dolphins on the U.S. east coast: 2002-2016

The objective of this analysis is to estimate the abundance of the five defined coastal morphotype bottlenose dolphin stocks along the U.S. Atlantic coast. This analysis involves two steps. First, due to the spatial overlap between the coastal and offshore morphotypes south of Cape Hatteras, genetic identifications of skin biopsy samples were used to model the probability that a particular bottlenose dolphin was of the coastal morphotype as a function of depth and latitude. Second, line transect aerial survey data was analyzed following the “Distance analysis” framework accounting for imperfect detection on the trackline. Within the abundance estimation procedure, we accounted for the probability that observed bottlenose dolphins were of the coastal morphotype using the probability model derived from biopsy data. Survey data were post-stratified to estimate the abundance of the different stocks. The results provide both a current abundance estimate and an assessment of recent trends in the size of the coastal bottlenose dolphin stocks.