309
Photo-identification work by Gamboa-Poveda (2009) suggested that overall residency rate is low for both dolphin species. Only 14% of Guiana dolphins and 12%
of bottlenose dolphins seem to regularly use the refuge. This result is likely biased
due to survey effort been limited to the refuge, as shown by recent boat surveys
extending from Gandoca to Changuinola. During this recent surveys, Guiana dolphin were observed south the Changuinola River, suggesting that their distribution
is larger than previously thought. Interestingly this does not seem to be the case for
the bottlenose dolphins from Gandoca-Manzanillo, whose seem to include offshore
waters.
Bottlenose dolphins have been documented in several parts of the Caribbean
coast of Panama including the Laguna of Chiriquí, but only those from the
Archipelago of Bocas del Toro are considered residents. In Bocas del Toro, the
population of bottlenose dolphins is small, highly predictable, and it appears to be
genetically isolated. Barragan-Barrera et al. (2015) described a unique mtDNA haplotype for this population, not found anywhere else in the Caribbean suggesting
some extent of genetic isolation. Microsatellite data also support the isolation of this
population even from neighboring Costa Rican bottlenose dolphins. Based on preliminary estimates, the population is considered to be between 80–100 animals, and
it seems to be organized into two communities one that has low residency rate
(<38.5%) and wider distribution, and a smaller communities that has more restricted
movement patterns and higher residency rate (38.5–100%) (May-Collado et al.
2015a).
This small community seems to be restricted in great part to a small semienclosed bay called Dolphin Bay, where due to its high predictability it is in constant interactions with dolphin-watching boats. May-Collado et al. (2012) found
that the number of boats interacting with these animals has increased exponentially
in the Bay; up to 40 boats have been counted to interact with the same group of
dolphins within a period of an hour (May-Collado et al. 2015). The increase in the
number of boats is correlated with an increase in underwater engine noise and dolphins seem to respond to this noise by modifying their whistles presumably to
reduce masking and by switching to avoidance behaviors (Kassamali-Fox et al.
2015; May-Collado and Wartzok 2008 2015, Sitar et al. 2016). Data shows that
these dolphins do not respond acoustically in the same way to other watercraft, for
example transport and other passing boats that are not directly targeting the animals,
rarely elicit changes in their acoustic behavior (May-Collado 2015). Interestingly,
interactions with dolphin watching boats vary depending on the animal behavior at
the moment of the interaction. For example, foraging dolphins interrupted by
dolphin watching boats lower the frequency and increase the duration of their communicative signals but when the animals were socializing not significant changes in
the acoustic structure of their signals were noted.
12 Ecology and Conservation of Cetaceans of Costa Rica and Panama
Photo-identification work by Gamboa-Poveda (2009) suggested that overall residency rate is low for both dolphin species. Only 14% of Guiana dolphins and 12%
of bottlenose dolphins seem to regularly use the refuge. This result is likely biased
due to survey effort been limited to the refuge, as shown by recent boat surveys
extending from Gandoca to Changuinola. During this recent surveys, Guiana dolphin were observed south the Changuinola River, suggesting that their distribution
is larger than previously thought. Interestingly this does not seem to be the case for
the bottlenose dolphins from Gandoca-Manzanillo, whose seem to include offshore
waters.
Bottlenose dolphins have been documented in several parts of the Caribbean
coast of Panama including the Laguna of Chiriquí, but only those from the
Archipelago of Bocas del Toro are considered residents. In Bocas del Toro, the
population of bottlenose dolphins is small, highly predictable, and it appears to be
genetically isolated. Barragan-Barrera et al. (2015) described a unique mtDNA haplotype for this population, not found anywhere else in the Caribbean suggesting
some extent of genetic isolation. Microsatellite data also support the isolation of this
population even from neighboring Costa Rican bottlenose dolphins. Based on preliminary estimates, the population is considered to be between 80–100 animals, and
it seems to be organized into two communities one that has low residency rate
(<38.5%) and wider distribution, and a smaller communities that has more restricted
movement patterns and higher residency rate (38.5–100%) (May-Collado et al.
2015a).
This small community seems to be restricted in great part to a small semienclosed bay called Dolphin Bay, where due to its high predictability it is in constant interactions with dolphin-watching boats. May-Collado et al. (2012) found
that the number of boats interacting with these animals has increased exponentially
in the Bay; up to 40 boats have been counted to interact with the same group of
dolphins within a period of an hour (May-Collado et al. 2015). The increase in the
number of boats is correlated with an increase in underwater engine noise and dolphins seem to respond to this noise by modifying their whistles presumably to
reduce masking and by switching to avoidance behaviors (Kassamali-Fox et al.
2015; May-Collado and Wartzok 2008 2015, Sitar et al. 2016). Data shows that
these dolphins do not respond acoustically in the same way to other watercraft, for
example transport and other passing boats that are not directly targeting the animals,
rarely elicit changes in their acoustic behavior (May-Collado 2015). Interestingly,
interactions with dolphin watching boats vary depending on the animal behavior at
the moment of the interaction. For example, foraging dolphins interrupted by
dolphin watching boats lower the frequency and increase the duration of their communicative signals but when the animals were socializing not significant changes in
the acoustic structure of their signals were noted.
12 Ecology and Conservation of Cetaceans of Costa Rica and Panama