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12.1 Pacific Coast
The list of cetacean species for the Pacific coast of Costa Rica includes about 28
species. However, information about the ecology and conservation status for most
of these species remains unknown. In the past 20 years research has focused primarily on three coastal species: bottlenose dolphins, spotted dolphins, and humpback
whales (e.g., Acevedo-Gutierrez and Burkhart 1998; Cubero-Pardo 1998;
Calambokidis et al. 2000; Garcia and Dawson 2003; May-Collado and MoralesRamirez 2005; May-Collado and Forcada 2012; Herrera-Miranda et al. 2016). We
will start providing a general background on what we know so far about these three
species.
The coastal subspecies of the spotted dolphin (Stenella attenuate graffmani) is
one of the 16 dolphin species inhabiting Costa Rican and Panamanian waters (MayCollado et al. 2005; May-Collado 2009) and possibly the most common dolphin off
the Pacific coast of both Costa Rica and Panama. In Costa Rica, coastal spotted
dolphin are commonly observed throughout the Pacific coast, however most of what
we know about these dolphins comes from a handful of locations: Cuajiniquil and
Gulf of Papagayo in the north Pacific and from Drake Bay, Osa Peninsula, and Gulf
Dulce and Isla del Caño in the south Pacific (e.g., Cubero 1998; Oviedo 2007;
Oviedo et al. 2014; May-Collado et al. 2005; Martinez-Fernandes et al. 2011, 2014).
In the north Pacific, coastal spotted dolphins appear to be resident year round
(Martinez-Fernandez et al. 2011; May-Collado et al. 2005; May-Collado and
Forcada 2012). The gulf is characterized by dry and rainy seasons. During the dry
season strong northeast trade winds generate the richest coastal upwelling of the
country, and spotted dolphin’s abundance seem to be associated to it. May-Collado
and Forcada (2012) found that the abundance of coastal spotted dolphins increased
linearly with water depth and transparency, and non-linearly with the dissolved oxygen concentration. Also, they found that high variability in the relative dolphin
abundance occurred during the dry season, a time where a higher number of spotted
dolphin groups were observed primarily in foraging activities (May-Collado and
Morales-Ramirez 2005). Therefore seasonal changes in relative abundance for these
dolphins probably are associated with food availability. Similar patterns were
described for the spotted dolphins of the Gulf Dulce by Cubero-Pardo (1998), but
no estimates of relative abundance were made, hindering further comparisons.
There is some evidence that at least some coastal spotted dolphins show high site
fidelity (May-Collado 2001). Thus, there is concern about the impact coastal human
activities may have on these animals. For instance, Montero-Cordero y Lobo (2010)
studied the impact of dolphin watching activities on coastal spotted dolphins that
inhabit the waters between Drake Bay and Caño Island. They found that the highest
density of dolphin groups accompanied by tour boats was near Caño Island. They
also found that when operators did not comply with conduct guidelines, the spotted
dolphins responded negative towards the boat, by swimming away. What this study
suggest is that even dolphin species that live in large group sizes are affected by
L.J. May-Collado et al.
12.1 Pacific Coast
The list of cetacean species for the Pacific coast of Costa Rica includes about 28
species. However, information about the ecology and conservation status for most
of these species remains unknown. In the past 20 years research has focused primarily on three coastal species: bottlenose dolphins, spotted dolphins, and humpback
whales (e.g., Acevedo-Gutierrez and Burkhart 1998; Cubero-Pardo 1998;
Calambokidis et al. 2000; Garcia and Dawson 2003; May-Collado and MoralesRamirez 2005; May-Collado and Forcada 2012; Herrera-Miranda et al. 2016). We
will start providing a general background on what we know so far about these three
species.
The coastal subspecies of the spotted dolphin (Stenella attenuate graffmani) is
one of the 16 dolphin species inhabiting Costa Rican and Panamanian waters (MayCollado et al. 2005; May-Collado 2009) and possibly the most common dolphin off
the Pacific coast of both Costa Rica and Panama. In Costa Rica, coastal spotted
dolphin are commonly observed throughout the Pacific coast, however most of what
we know about these dolphins comes from a handful of locations: Cuajiniquil and
Gulf of Papagayo in the north Pacific and from Drake Bay, Osa Peninsula, and Gulf
Dulce and Isla del Caño in the south Pacific (e.g., Cubero 1998; Oviedo 2007;
Oviedo et al. 2014; May-Collado et al. 2005; Martinez-Fernandes et al. 2011, 2014).
In the north Pacific, coastal spotted dolphins appear to be resident year round
(Martinez-Fernandez et al. 2011; May-Collado et al. 2005; May-Collado and
Forcada 2012). The gulf is characterized by dry and rainy seasons. During the dry
season strong northeast trade winds generate the richest coastal upwelling of the
country, and spotted dolphin’s abundance seem to be associated to it. May-Collado
and Forcada (2012) found that the abundance of coastal spotted dolphins increased
linearly with water depth and transparency, and non-linearly with the dissolved oxygen concentration. Also, they found that high variability in the relative dolphin
abundance occurred during the dry season, a time where a higher number of spotted
dolphin groups were observed primarily in foraging activities (May-Collado and
Morales-Ramirez 2005). Therefore seasonal changes in relative abundance for these
dolphins probably are associated with food availability. Similar patterns were
described for the spotted dolphins of the Gulf Dulce by Cubero-Pardo (1998), but
no estimates of relative abundance were made, hindering further comparisons.
There is some evidence that at least some coastal spotted dolphins show high site
fidelity (May-Collado 2001). Thus, there is concern about the impact coastal human
activities may have on these animals. For instance, Montero-Cordero y Lobo (2010)
studied the impact of dolphin watching activities on coastal spotted dolphins that
inhabit the waters between Drake Bay and Caño Island. They found that the highest
density of dolphin groups accompanied by tour boats was near Caño Island. They
also found that when operators did not comply with conduct guidelines, the spotted
dolphins responded negative towards the boat, by swimming away. What this study
suggest is that even dolphin species that live in large group sizes are affected by
L.J. May-Collado et al.