Long-term site fidelity of bottlenose dolphins in Cardigan Bay, Wales

Project Last Updated: 10/12/2004 20:52:00 Source : Sergi Perez

Collaborators: Sea Watch Foundation, Friends of Cardigan Bay and University of Wales, Bangor

Cardigan Bay, Wales, is one of the three places in the UK and Ireland where bottlenose dolphins can be seen regularly. Boat-based photo-identification surveys have been carried out in this area since the late 1980’s.

Photo identification effort has focused on an area of approximately 1,000 km2 that was designated as the Cardigan Bay candidate Special Area of Conservation (cSAC) in 1996. In this study, we compare identification catalogues of bottlenose dolphins that were obtained by different research teams.

The data sets include catalogues from two available reports and three sets of unpublished identification pictures. The study periods were 1990-1993, 2001 and 2003-2004. Sighting patterns were separated into 3 categories: 1) animals seen in all three periods (N= 12), 2) animals seen in 2001 and 2003-2004 (N= 29) and 3) animals only seen 2003-2004 (N=88). Re-sightings of dolphins range from 4 to 42 times. When possible, tentative sex, birth dates and reproductive histories were allocated to identified dolphins.

Plots of locations where dolphins identified more than 20 times were seen indicated that certain individuals exhibited a preference for specific areas within Cardigan Bay. The present study demonstrated for the first time that there is a population of bottlenose dolphins in Cardigan Bay whose long-term seasonal residency extends over more than 15 years.

In addition, we provided information, such as cross-referenced identification catalogues, sightings histories and demographic data, which are useful for future management and monitoring programmes.