Abundance of the Common Bottlenose Dolphin, Tursiops truncatus (Montagu, 1821) (Mammalia: Artiodactyla: Delphinidae) off the South and West Coasts of Puerto Rico

The abundance of the common bottlenose dolphin, Tursiops truncatus (Montagu, 1821), was investigated by mark-recapture methods using photographic surveys on the south and west coasts of Puerto Rico from 2013 to 2015. The number of individuals having distinctive marks was 62, representing 46.5% of dolphins observed. Additionally, two dorsal fins were matched with photos taken during a study in 2000, making this the first report of long-term resightings in Puerto Rico. The abundance estimate for the south and west coast of Puerto Rico was of 127 dolphins. This represents a statistically significant, 60% decrease from the reported estimate back in 2001. It is unclear whether this decline is due to emigration, mortality, or a combination of the two. Management should prioritize further studies on the health of this population and the potential factors contributing to the decline, such as overfishing or excessive boat traffic.