Golfo Dulce IMMA

Size in Square Kilometres

910 km2

Qualifying Species and Criteria

Common bottlenose dolphin – Tursiops truncatus 

Criterion B (1)

Pantropical spotted dolphin – Stenella attenuata

[Coastal – S. a. graffmani]

Criterion B (1)

Humpback whale – Megaptera novaeangliae

[North Pacific – M. n. kuzira]

Criterion C (1)

[Southern – M. n. australis]

Criterion C (1)

Marine Mammal Diversity 

Pseudorca crassidens, Steno bredanensis

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Golfo Dulce is a rare ‘tropical fjord’ in southwestern Costa Rica that provides several critical habitats for cetaceans. North of the mouth of the gulf (500-m), two resident populations of coastal dolphins show year-round site fidelity for foraging and calving. They exhibit habitat partitioning, with common bottlenose dolphins (Tursiops truncatus) occurring primarily close to shore, especially near river mouths, and inshore pantropical spotted dolphins (Stenella attenuata graffmani) foraging in the deeper waters of the middle of the gulf. Two populations of humpback whales (Megaptera novaeangliae) from both the Northern (M. n. kuzira) and Southern Hemispheres (M. n. australis) use the Golfo Dulce as critical calving and reproductive habitat, evidenced by observations of mother-calf pairs engaged in nursing behaviour and singing males. False killer whales (Pseudorca crassidens) are also commonly seen in the Golfo Dulce IMMA, adding to the abundance of marine life that marks the inlet as a biodiversity hotspot.

Description of Qualifying Criteria

Criterion B: Distribution and Abundance

Sub-criterion B1: Small and Resident Populations

Sympatric common bottlenose dolphins (Tursiops truncatus) and coastal pantropical spotted dolphins (Stenella attenuata graffmani) are considered year-round residents (Acevedo-Gutiérrez & Burkhart, 1998; Cubero-Pardo, 2007; Oviedo, 2007) with a significant level of photographic recaptures and site fidelity (Pacheco-Polanco, 2016; Oviedo, 2018; Oviedo et al., 2018). Calving areas for bottlenose dolphins have been identified in coastal areas near river mouths, where resident females form nursing groups (CEIC, unpubl. data). River mouths also serve as key foraging habitat for that species (Oviedo, 2007; Herra-Miranda et al., 2016; Pacheco-Polanco, 2016; Oviedo et al., 2018, 2019). Pantropical spotted dolphin nursing groups have been recorded in the species’ core foraging habitat (CEIC, unpubl. data), which covers a sizeable area of the deep inner basin, where the dolphins follow the movement of preferred prey species, such as ballyhoo (Hemiramphidae sp.) and flying fish (Exocoetidae sp.) (Oviedo 2007; Oviedo et al., 2018). Modelled photo-identification data indicate relatively small populations of 119 (95% CI: 108.55–130.35) bottlenose dolphins and 368 (95% CI: 341.51–396.31) spotted dolphins (Oviedo, 2018).

Criterion C: Key Life Cycle Activities

Sub-criterion C1: Reproductive Areas

North Pacific humpback whales (Megaptera novaeangliae kuzira) belong to the Central America Distinct Population Segment, designated under the United States Endangered Species Act (Bettridge, 2015). Southern Hemisphere humpback whales (Megaptera novaeangliae australis) belong to the population designated by the International Whaling Commission as Breeding Stock G. Both these populations seasonally migrate to the Eastern Tropical Pacific, and use Golfo Dulce for reproduction during their respective wintering seasons (Acevedo-Gutierrez & Smultea 1995; Oviedo et al; 2009, 2015). This unusual geographical overlap allows potential trans-equatorial genetic exchange (Medrano-González et al., 2001). The whales spend time in both the inner basin and sill area (Oviedo et al., 2015; Herra-Miranda et al., 2016; Pelayo-González et al., in review). Neonates have been documented (Bessesen, 2015), and mothers with nursing calves have been demonstrated to prefer the coastal areas, especially along western portion of the sill area, while singing males and competitive groups remain in the deep waters (Herra-Miranda et al., 2016).

The Southeast Pacific humpback whale carries out long seasonal migrations from feeding grounds off the coasts of southern Chile and Antarctica to winter calving grounds in tropical waters. Humpback whales from the Southern Hemisphere have multiple wintering areas comprising a large breeding habitat in Central America including Golfo Dulce, Costa Rica. The region is utilized between July and November with high numbers of documented observations of mother-calf pairs and mature males (Acevedo-Gutierrez & Smultea, 1995). By contrast, the number of observations of the Central American humpback whales in both Golfo Dulce and Osa Peninsula IMMAs, recorded between December and April, have declined in recent years(Pelayo-Gonzalez et al., in press), and sightings of this subpopulation are not as frequent as those whales migrating from the Southern Hemisphere. Calves from the Northern Hemisphere are commonly observed (Bessesen, 2015) but behaviours related to reproduction such as competitive groups have yet to be documented during the Northern Hemisphere breeding season.

According to historical data in Golfo Dulce (July–October 2010–2019), humpback whales primarily occur in the channel that communicates the inner basin with the Pacific within 100 m isobaths. Single adults concentrate in the central part of the mouth while mothers with calves are found nearer the coast, primarily in the western portion between Puerto Jimenez and Cabo Matapalo. Two additional areas are identified by a spatial usage trend: the coastline from the entrance of Golfito towards Punta Gallardo; and along the northern coast of Golfo Dulce from the western side of Punta Estrella towards the Esquinas River. These aggregation areas could result from calving females moving away from the sill area where they are most likely to encounter males. Competitive groups and singing males are mainly observed in the sill area (Herra-Miranda et al., 2016).

Supporting Information

Acevedo-Gutierrez, A., and Smultea, M. 1995. First records of Humpback whales including calves at Golfo Dulce and Isa del Coco, Costa Rica, suggesting geographical overlap of northern and southern hemisphere populations. Marine Mammal Science 11(4):554–560.

Acevedo-Gutiérrez, A., and Burkhart, S. 1998. Seasonal distribution of bottlenose (Tursiops truncatus) and pan-tropical spotted (Stenella attenuata) dolphins (Cetacea: Delphinidae) in Golfo Dulce, Costa Rica. Revista de Biología Tropical 46:91–101.

Acuña-González, J.A., Vargas-Zamora, J.A., and Córdoba-Muñoz R. 2006. A snapshot view of some vertical distributions of water parameters at a deep (200 m) station in the fjord-like Golfo Dulce, embayment, Costa Rica. Revista de Biología Tropical 54 (Suppl.1):193–200.

Alvarado, J.J., Cortés, J., Esquivel, M.F., and Salas, E. 2012. Costa Rica’s Marine Protected Areas: status and perspectives. Revista de Biología Tropical 60 (1):129–142.

Bessesen, B. 2015. Occurrence and distribution patterns of several marine vertebrates in Golfo Dulce, Costa. Revista de Biología Tropical 63(2): 261–272.

Bessesen, B., Oviedo, L., Burdett Hart, L., Herra-Miranda, J.D., Pacheco-Polanco J.D., Baker, L., Saborío-R, G., Bermúdez-Villapol, L., and Acevedo-Gutiérrez, A. 2014. Lacaziosis-like disease among bottlenose dolphins Tursiops truncatus photographed in Golfo Dulce, Costa Rica. Diseases of Aquatic Organisms, 107:173–180.

CBD. 2022. Ecologically or Biologically Significant Areas (EBSAs): Corredor Marino del Pacífico Oriental tropical. Center for Biological Diversity,

Cubero-Pardo, P. 2007. Distribución y condiciones ambientales asociadas al comportamiento del delfín bufeo (Tursiops truncatus) y el delfín manchado (Stenella attenuata) (Cetacea: Delphinidae) en el Golfo Dulce, Costa Rica. Revista de Biología Tropical 55:549–557.

Fargier, L., Hartmann, H., and Molina-Ureña, H. 2014. “Marine Areas of Responsible Fishing”: A Path Toward Small-Scale Fisheries Co-Management in Costa Rica? Perspectives from Golfo Dulce. In: Amezcua F, Bellgraph B (eds.) Fisheries Management of Mexican and Central American Estuaries, Estuaries of the World, pp. 155–181. Dordrecht: Springer.

Fournier, M.L., Castillo, L.E., Ramírez, F., Moraga, G., and Ruepert, C. 2019. Evaluación preliminar del área agrícola y su influencia sobre la calidad del agua en el Golfo Dulce, Costa Rica. Revista de Ciencias Ambientales 53(1):92–112.

GEBCO Compilation Group 2021. GEBCO 2014 Grid. doi:10.5285/c6612cbe-50b3-0cff-e053-6c86abc09f8f.

Herra-Miranda, D., Pacheco-Polanco, D., Oviedo, L., and Iñíguez, M. 2016. Análisis espacial de los hábitats críticos del delfín nariz de botella Tursiops truncatus y la ballena jorobada Megaptera novaeangliae en Golfo Dulce, Costa Rica: Consideraciones acerca de un proyecto de construcción de marina. Revista de Ciencias Marinas y Costeras REVMAR 8(1):9-27.

Hebbeln, D., Beese, D, and Cortés, J. 1996. Morphology and sediment structures in Golfo Dulce, Costa Rica. Revista de Biología Tropical 44(Supl.3):1–10.

MAG. 2018. Decree N° 41003-MOPT-SP-MINAE/N° 41086-MAG. Ministra A.I. De Agricultura Y Ganadería de Costa Rica, San Jose.

Medrano-González, L., Baker, C.S., Robles-Saavedra, M.R., Murrell, J., Vázquez-Cuevas, M.J., Congdon, B.C., Straley, J.M., Calambokidis, J., Urbán-Ramírez, J., Flórez-González, L., Olavarria-Barrera, C., Aguayo-Lobo, A., Nolasco-Soto, J., Juárez-Salas, R.A., and Villavicencio-Llamosas, K. 2001. Trans-oceanic population genetic structure of humpback whales in the north and south pacific. Memoirs of the Queensland Museum 47(2):465–479.

Mission Blue. 2019. Hope spot declared at Golfo Dulce, Costa Rica in support of nursery for endangered scalloped hammerhead sharks. Sylvia Earl Alliance.

Morales-Ramírez, A., Acuña-Gonzáles, J., Lizano, O., Alfaro, E. and Gómez, E. 2015. Rasgos oceanográficos en el Golfo Dulce, Pacífico de Costa Rica: una revisión para la toma de decisiones en conservación marina. Revista de Biología Tropical 63(1):13–160.

Oviedo, L. 2007. Dolphin sympatric ecology in a tropical fjord: habitat partitioning by bathymetry and topography as a strategy to coexist. Journal of Marine Biological Association of the United Kingdom 87:1327–1335.

Oviedo, L. 2018. Patrones y procesos de selección de hábitat en delfines simpátricos en Golfo Dulce, Costa Rica. PhD Thesis, Centro Interdisciplinario de Ciencias Marinas, IPN.

Oviedo, L., Fernández, M., Herra-Miranda, D., Pacheco-Polanco, J.D., Hernández-Camacho C. and Aurioles-Gamboa, D. 2018. Habitat partitioning mediates the coexistence of sympatric dolphins in a tropical fjord-like embayment. Journal of Mammalogy 99(3):554–64.

Oviedo, L., Fernández, M., Pacheco-Polanco, J.D., and Herra-Miranda D. 2019. Spatial analysis on the occurrence of inshore and offshore bottlenose dolphins (Tursiops truncatus) in Osa Peninsula waters and Golfo Dulce. Journal of Cetacean Research Management 20:1–11.

Oviedo, L., Herra-Miranda, D., Pacheco-Polanco, J.D., Figgener, C., Marquez-Artavia, A., Quirós Pereira, W. and Iñiguez., M. 2015. Diversidad de cetáceos en el paisaje marino-costeros de Golfo Dulce, Península de Osa, Costa Rica. Revista de Biología Tropical 63(2):395–406.

Oviedo, L., Pacheco-Polanco, J.D., and Herra-Miranda, D. 2009. Evaluación de los riesgos de afectación por el establecimiento de granjas atuneras en relación con la distribución espacial de cetáceos en el Golfo Dulce, Costa Rica. Revista Ciencias Marinas y Costeras REVMAR 1:159–174.

Pacheco-Polanco, J.D. 2016. La población residente de delfines nariz de botella (Tursiops truncatus) ecotipo costero en el Golfo Dulce, Costa Rica: aspectos ecológicos y socio-económicos para una gestión integrada del recurso. Tesis para optar al grado y título de Maestría Académica en Gestión Integrada de Áreas Costeras Tropicales. Universidad de Costa Rica. Costa Rica. 128 pp.

Pelayo-González, L., Oviedo, L., Marques-Artavia, A., Herra-Miranda, D., Pacheco-Polanco, J.D., Bessesen, B., and H. M. Guzmán (in review). Habitat use of Southeast Pacific humpback whales (Megaptera novaeangliae; Borowski 1781) in Golfo Dulce, Costa Rica. Marine and Freshwater Research.

Pelayo-González L, Herra-Miranda D, Pacheco-Polanco JD, Guzmán HM, Goodman S and Oviedo, L. (in press). Decreases in encounter rate of endangered northeast Pacific humpback whales in Southern Costa Rica: Possible changes in migration pattern due to warming events. Front. Mar. Sci. 9:927276. doi: 10.3389/fmars.2022.927276

Quesada, M.A., Cortés, J. 2006. Golfo Dulce In: Nielsen Muñoz V, Quesada Alpízar MA (eds.) Ambientes Marino Costeros de Costa Rica, pp. 167–176. Informe técnico. CIMAR, CI, TNC, San José.

Quiros-Alvares, G. 2003. Circulación del Golfo Dulce: un fiordo tropical. Topografía Meteorología y Oceanografía 10(2):75–83.

Rincón-Alejos, F., Ballestero-Sakson, D. 2015. Hidrografía y plumas estuarinas en Golfo Dulce, Pacífico Sur de Costa Rica. Revista de Biología Tropical 63(2):161–181.

Sánchez-Robledo, Oviedo, L., Herra-Miranda, D., Pacheco-Polanco J.D., Goodman, S., and Guzmán, H. 2020. The Abundance of False Killer Whaler, Pseudorca crassidens (Artiodactyla: Delphinidae) in coastal waters of Golfo Dulce and Osa Peninsula, Costa Rica. Revista de Biología Ambiental 68(2):1–10.

Spongberg, A.L., Witter, J.D., Acuña, J., Vargas, J., Murillo, M., Umaña, G., Gómez, E., Prerez, G. 2011. Reconnaissance of selected PPCP compounds in Costa Rican surface waters. Water Research 45(20):6709–6717.

Svendsen, H., Rosland, R., Myking, S., Vargas, J.A., Lizano, O.G., and Alfaro, E.C. 2006. A physical oceanographic study of Golfo Dulce, Costa Rica. Revista de Biología Tropical 54(1):147–170.

Wolff, M., Hartman, H.J, Koch, V. 1996. A pilot trophic model for Golfo Dulce, a tropical fjord-like embayment, Costa Rica. Revista de Biología Tropical 44:215−231.


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