Female Productivity and Calf Survivorship of Bottlenose Dolphins (Tursiops truncatus) in Bocas del Toro, Panama
Conference Year
January 2021
Abstract
The resident bottlenose dolphins of the Archipelago of Bocas del Toro, a small populations which shows high levels of philopatry, are regularly exposed to intense interactions with dolphin-watching boats. Previous research has shown that Bocas dolphin foraging and social behavior is disrupted throughout the day by tour boats. This has created concerns about the health of the population, in regards to calf survival and female fecundity. In this study we used photo-identification data of the natural marks on the dorsal fins on the females from 2004 to 2015 to infer female fecundity and calf mortality rates. 44 females and 56 calves were identified from 140 dolphins in the current catalogue. A total of 23 females reside in Dolphin Bay, the area where most interactions with tour boats occur. The other 12 females have home ranges primarily outside the bay. Our results indicate that during the study period, females had between one and three calves, with a median calving cycle of 72 months and mean of 60.8 months (SD: 22.75 months, Range: 18-96 months). Calf mortality was estimated to be 0.55 with a survival rate of 0.45. These results indicate that females in Bocas del Toro have longer resting time between calves and that the calf mortality rate is greater than other bottlenose dolphin populations considered at risk. While we do not know what is driving these patterns, it is important to highlight that during the years when the data was collected, a separate study found that dolphin watching tour boats significantly decreased dolphins foraging budgets while increasing avoidance behavior, such as traveling. Such interruptions can result in high energetic cost to nursing mothers and their calves. While compliance to whale-watching regulations by tour operators is urgent, we urge the establishment of a Marine Protected Area that regulates boat traffic.
Primary Faculty Mentor Name
Dr. Laura May-Collado
Status
Undergraduate
Student College
College of Arts and Sciences
Program/Major
Zoology
Primary Research Category
Biological Sciences
Female Productivity and Calf Survivorship of Bottlenose Dolphins (Tursiops truncatus) in Bocas del Toro, Panama
The resident bottlenose dolphins of the Archipelago of Bocas del Toro, a small populations which shows high levels of philopatry, are regularly exposed to intense interactions with dolphin-watching boats. Previous research has shown that Bocas dolphin foraging and social behavior is disrupted throughout the day by tour boats. This has created concerns about the health of the population, in regards to calf survival and female fecundity. In this study we used photo-identification data of the natural marks on the dorsal fins on the females from 2004 to 2015 to infer female fecundity and calf mortality rates. 44 females and 56 calves were identified from 140 dolphins in the current catalogue. A total of 23 females reside in Dolphin Bay, the area where most interactions with tour boats occur. The other 12 females have home ranges primarily outside the bay. Our results indicate that during the study period, females had between one and three calves, with a median calving cycle of 72 months and mean of 60.8 months (SD: 22.75 months, Range: 18-96 months). Calf mortality was estimated to be 0.55 with a survival rate of 0.45. These results indicate that females in Bocas del Toro have longer resting time between calves and that the calf mortality rate is greater than other bottlenose dolphin populations considered at risk. While we do not know what is driving these patterns, it is important to highlight that during the years when the data was collected, a separate study found that dolphin watching tour boats significantly decreased dolphins foraging budgets while increasing avoidance behavior, such as traveling. Such interruptions can result in high energetic cost to nursing mothers and their calves. While compliance to whale-watching regulations by tour operators is urgent, we urge the establishment of a Marine Protected Area that regulates boat traffic.