Presencia y comportamiento de dos especies de delfines en el Pacífico Central de Costa Rica
Archivos
Fecha
2006
Autores
Palacios Alfaro, José David
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Editor
Universidad Nacional (Costa Rica)
Resumen
En Costa Rica se conocen cerca de 30 especies de cetáceos tanto en el Océano Pacífico y/o en el Mar Caribe. En la Zona Económica Exclusiva del Pacífico de Costa Rica se ha confirmado la presencia de 19 especies de cetáceos y, donde los estudios desarrollados se han concentrado en el Pacífico Norte y Sur mientras que el Pacífico Central no se ha realizado ningún estudio. Por lo tanto, se llevó a cabo un estudio de cetáceos en la zona del Pacífico Central del país, con el fin de generar información básica (presencia, densidad relativa, tamaño y estructura grupal, comportamiento e interacción con la pesquería camaronera). Este inicio en diciembre del 2004 y finalizó en marzo del 2005. Durante este período se avistaron tres especies de cetáceos, el delfin nariz de botella (Tursiops truncatus) se observó en 106 ocasiones, seguido del delfin manchado (Stenella attenuata, n = 26) y de un balaenoptérido no identificado (Balaenoptera sp. n = 1). La mayoría de los avistamientos se presentaron en la parte más externa del Golfo de Nicoya y en sus zonas aledañas. En el delfin manchado la densïidad relativa (0.03 + 0.05 Avist. / Km.) fue menor con respecto a la del delfin nariz de botella (0.15 + 0.16 Avist. / Km.). El tamaño grupal fue mayor para el delfín nariz de botella (7.05 + 7.14 ind.), mientras para el delfin manchado fue 5.15 (+ 5.58 ind.). Para arabas especies de delfines los grupos estuvieron formados en mayor frecuencia por individuos adultos con un 61% (S. attenuata) y 65% (7. truncatus). El delfin manchado presentó una mayor frecuencia de actividades de alimentación (49 %), seguido de las actividades sociales (40%) y de desplazamiento (11%). En el delfin nariz de botella las actividades de alimentación se presentaron con mayor frecuencia (74%), seguidas de las sociales (22%), de desplazamiento (3%) y finalmente de las actividades de descanso (1 %). Con respecto -a la interacción con la embarcación camaronera tanto el delfin manchado como el delfin nariz de botella presentaron asociación, donde en el 73% de los avistamientos de cada especie hubo interacción con la embarcación. Este último factor tiene gran influencia sobre la presencia, tamaño grupal y comportamiento de las especies de delfines avistadas, ya que ambas siguen a las embarcaciones camaroneras para alimentarse de la fauna acompañante del camarón “FACA” que es descartada después de la selección del producto. Este es el primer reporte de interacción de cetáceos con este tipo de pesquería en el país. La estructura grupal encontrada sugiere que ambas especies siguen los purones de sociedades de fusión-fisión reportados para otras poblaciones costeras de delfines, aunque es necesario desarrollar investigaciones para confirmar este patrón. Además, se recomienda realizar estudios para conocer el rango espacial en el cual se presenta la interacción de los cetáceos y este tipo de pesquería a lo largo de la costa Pacífica del país.
In Costa Rica, about 30 species of cetaceans are known both in the Pacific Ocean and/or in the Caribbean Sea. In the Exclusive Economic Zone of the Pacific of Costa Rica, the presence of 19 species of cetaceans has been confirmed and, where the studies carried out have concentrated on the North and South Pacific, while no study has been carried out on the Central Pacific. Therefore, a study of cetaceans in the Central Pacific area of the country was carried out, in order to generate basic information (presence, relative density, size and group structure, behavior and interaction with the shrimp fishery). This began in December 2004 and ended in March 2005. During this period three species of cetaceans were sighted, the bottlenose dolphin (Tursiops truncatus) was observed on 106 occasions, followed by the spotted dolphin (Stenella attenuata, n = 26). and from an unidentified balaenopterid (Balaenoptera sp. n = 1). Most of the sightings occurred in the outermost part of the Gulf of Nicoya and in its surrounding areas. In the spotted dolphin, the relative density (0.03 + 0.05 sights/km) was lower than that of the bottlenose dolphin (0.15 + 0.16 sights/km). Group size was greater for the bottlenose dolphin (7.05 + 7.14 ind.), while for the spotted dolphin it was 5.15 (+ 5.58 ind.). For Arabian dolphin species, the groups were formed more frequently by adult individuals with 61% (S. attenuata) and 65% (7. truncatus). The spotted dolphin presented a higher frequency of feeding activities (49%), followed by social activities (40%) and displacement (11%). In the bottlenose dolphin, feeding activities occurred more frequently (74%), followed by social activities (22%), movement activities (3%) and finally resting activities (1%). Regarding the interaction with the shrimp boat, both the spotted dolphin and the bottlenose dolphin presented an association, where in 73% of the sightings of each species there was interaction with the boat. This last factor has a great influence on the presence, group size and behavior of the species of dolphins sighted, since both follow the shrimp boats to feed on the accompanying fauna of the "FACA" shrimp that is discarded after the selection of the product. This is the first report of interaction of cetaceans with this type of fishery in the country. The group structure found suggests that both species follow the fusion-fission societies reported for other coastal populations of dolphins, although research is needed to confirm this pattern. In addition, it is recommended to carry out studies to know the spatial range in which the interaction of cetaceans and this type of fishery occurs along the Pacific coast of the country.
In Costa Rica, about 30 species of cetaceans are known both in the Pacific Ocean and/or in the Caribbean Sea. In the Exclusive Economic Zone of the Pacific of Costa Rica, the presence of 19 species of cetaceans has been confirmed and, where the studies carried out have concentrated on the North and South Pacific, while no study has been carried out on the Central Pacific. Therefore, a study of cetaceans in the Central Pacific area of the country was carried out, in order to generate basic information (presence, relative density, size and group structure, behavior and interaction with the shrimp fishery). This began in December 2004 and ended in March 2005. During this period three species of cetaceans were sighted, the bottlenose dolphin (Tursiops truncatus) was observed on 106 occasions, followed by the spotted dolphin (Stenella attenuata, n = 26). and from an unidentified balaenopterid (Balaenoptera sp. n = 1). Most of the sightings occurred in the outermost part of the Gulf of Nicoya and in its surrounding areas. In the spotted dolphin, the relative density (0.03 + 0.05 sights/km) was lower than that of the bottlenose dolphin (0.15 + 0.16 sights/km). Group size was greater for the bottlenose dolphin (7.05 + 7.14 ind.), while for the spotted dolphin it was 5.15 (+ 5.58 ind.). For Arabian dolphin species, the groups were formed more frequently by adult individuals with 61% (S. attenuata) and 65% (7. truncatus). The spotted dolphin presented a higher frequency of feeding activities (49%), followed by social activities (40%) and displacement (11%). In the bottlenose dolphin, feeding activities occurred more frequently (74%), followed by social activities (22%), movement activities (3%) and finally resting activities (1%). Regarding the interaction with the shrimp boat, both the spotted dolphin and the bottlenose dolphin presented an association, where in 73% of the sightings of each species there was interaction with the boat. This last factor has a great influence on the presence, group size and behavior of the species of dolphins sighted, since both follow the shrimp boats to feed on the accompanying fauna of the "FACA" shrimp that is discarded after the selection of the product. This is the first report of interaction of cetaceans with this type of fishery in the country. The group structure found suggests that both species follow the fusion-fission societies reported for other coastal populations of dolphins, although research is needed to confirm this pattern. In addition, it is recommended to carry out studies to know the spatial range in which the interaction of cetaceans and this type of fishery occurs along the Pacific coast of the country.
Descripción
Palacios Alfaro, J. D. (2006). Presencia y comportamiento de dos especies de delfines en el Pacífico Central de Costa Rica. [Tesis de Licenciatura]. Universidad Nacional, Costa Rica.
Palabras clave
CETACEA, DELFIN, DOLPHIN