Chiloé Interior IMMA
Size in Square Kilometres
2 794 km2
Qualifying Species and Criteria
Chilean dolphin – Cephalorhynchus eutropia
Criterion A; B (1)
Peale’s dolphin – Lagenorhynchus australis
Criterion C (1)
Burmeister’s porpoise – Phocoena spinipinnis
Criterion C (1)
Marine Mammal Diversity
Otaria byronia, Lontra felina, Lontra provocax
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The Chiloé Interior IMMA includes the east coast of Isla Chiloé Grande and the islands to the east extending to approximately the 100 m depth contour. The archipelago is home to three small cetacean species that differ in their fine scale habitat use. Cetacean habitat overlaps extensively with areas used for shellfish and salmon farming. Chilean dolphins (Cephalorhynchus eutropia) inhabit shallow waters (less than 30m deep), close to shore in sheltered bays and estuaries. Chilean dolphins seem to form resident populations of 40-120 individuals with no evidence of regular movements between adjacent areas. Peale’s dolphins (Lagenorhynchus australis) and Burmeister’s porpoises (Phocoena spinipinnis) are more widely distributed in the inner seas but consistently occupy the same areas between years. All three species use the area for reproduction, feeding and socialising. South American sea lions also abound, in particular in proximity to aquaculture installations. Marine otters and river otters are seen regularly off the southern Chiloé coastline.
Description of Qualifying Criteria
Criterion A – Species or Population Vulnerability
Chilean dolphins (Cephalorhynchus eutropia) are endemic to south-central and southern Chile and are listed as Near Threatened (NT) on the IUCN Red List (Heinrich and Reeves, 2017). The range-wide abundance is not known but the species is thought to number in the low thousands which, if confirmed, would meet the criteria for Vulnerable (VU) status (Heinrich and Reeves, 2017). An up-listing of the species’ conservation status to Vulnerable would reflect the ongoing concerns about bycatch affecting the dolphins along the open coast as well as in the Tenth (Xth) Region which includes Chiloé (Pérez-Alvarez et al., 2021). Chilean dolphins along the open coast to the north of Chiloé are considered genetically distinct from those of the southern fjord region (Pérez-Alvarez et al., 2015). The exact genetic boundary is not clear as samples have not been analysed from Chiloé but this area most likely constitutes the transition zone between northern and southern populations.
Criterion B: Distribution and Abundance
Sub-criterion B1: Small and Resident Populations
Chilean dolphins inhabit discrete nearshore habitat that is characterised by shallow depth (less than 30m), very near to shore (within 1 km), often with estuarine conditions and areas of strong tidal flow (Heinrich et al., 2019). Mother-calf pairs including neonates are observed during the spring to autumn period with dolphins breeding and feeding across the area they occupy (Heinrich, 2006; Heinrich et al., 2019). The populations of Quellón and Castro/Dalcahue have been studied since 2001 (Heinrich, 2006) and habitat preference has remained stable for decades with the same channels and bay occupied over years (Heinrich et al., 2019). Passive acoustic monitoring also indicates that Chilean dolphins also occupy the same channels and bays year-round (Filun, 2015, Hack et al., in prep) as do photo-identification studies (Heinrich, 2006, Heinrich and Espinosa-Miranda, 2019, Heinrich et al., in prep). In the Quellón area, where photo-ID effort spans 20 years, individuals show clear small-scale site fidelity (Heinrich, 2006) with one individual resighted in 2019 within 1,000 m of the 2001 sighting location (Heinrich, unpublished data). Chilean dolphins seem to form discrete local populations along the coast with no confirmed individual movement even between adjacent study areas (Heinrich et al., in prep). Local population size in Quellón seems to have remained stable at around 60 adult individuals (Heinrich, 2006, Heinrich and Espinosa-Miranda, 2019; Heinrich et al., in prep). For other areas within the IMMA population size estimates range from 40 to 120 individuals (Inio: 40; Quellón: 60, Queilen: 123, Castro/Dalcahue: 30-40, Quemchi: 44) giving a combined total of around 300 Chilean dolphins in the inner seas of Chiloé (Heinrich, 2021; Heinrich and Espinosa-Miranda, 2019; Heinrich et al., in prep). A compilation of sighting data from all other available sources further supports the discrete distribution patterns of Chilean dolphins in the inner seas of Chiloé with no sightings to the east into the Corcovado Gulf or in waters deeper than 100 m ( Hucke-Gaete et al., 2022).
Criterion C: Key Life Cycle Activities
Sub-criterion C1: Reproductive Areas
Peale’s dolphins and Burmeister’s porpoises share the inshore waters of Chiloé with Chilean dolphins, and although all three species overlap, their preferred habitat differs. Peale’s dolphins are more widely distributed, and use more exposed coastline with less reliance on estuarine characteristics than Chilean dolphins (Heinrich et al., 2019). Burmeister’s porpoises are usually seen in slightly deeper waters from 30 to 100m depth (Heinrich, 2006; Genov, 2012). In all areas both Peale’s dolphins and Burmeister’s porpoises are observed regularly with neonates and calves. There is no evidence for specific nursing areas but mother-neonate pairs of both species tend to be sighted along more sheltered coastline and closer to shore than groups without neonates. Both species also feed and socialise in the same area that they occupy regularly (Heinrich, 2006; Heinrich, unpublished data).
Population size estimates are not available for Peale’s dolphins or Burmeister’s porpoises. Both species are more frequently encountered in the central part of Chiloé. Photo-ID data indicated that Peale’s dolphins tended to be more abundant than Chilean dolphins in the long-term study areas of Quellón and Castro respectively (Heinrich, 2006). Individually identified Peale’s dolphins were resighted between months and years in the same areas indicating at least some degree of site fidelity (Heinrich, 2006). Peale’s dolphins and Burmeister’s porpoises seem to extend further into the deeper waters of Golfo Corcovado than Chilean dolphins. There are no data available on the year-round presence of either species as systematic surveys in winter are lacking. However, both species are seen regularly in the same species-specific areas indicating that their use of those areas has been stable over time (Heinrich et al., 2019).
Camus, P. A. 2001. ‘Marine biogeography of continental Chile.’ Revista Chilena de Historia Natural 74:587-617.
Espinosa-Miranda, C., Cáceres, B., Blank, O., Fuentes Riquelme, M. and Heinrich, S. 2020. ‘Entanglements and Mortality of Endemic Chilean Dolphins (Cephalorhynchus eutropia) in Salmon Farms in Southern Chile.’ Aquatic Mammals 46:337-343.
Filun Hernández, Diego A. 2015. Implementación de un monitoreo acústica pasivo para delfín chileno Cephalorhynchus eutropia (Gray, 1846) en el sur de Chiloé, para conocer su ocurrencia estacional y su interacción con la actividad acuicolar de la zona. Tesis de Grado, Biología Marina, Universidad Austral de Chile, Valdivia, Chile. pp. 65
Genov, T. 2012. Modelling habitat preference of small cetaceans in southern Chile. MRes thesis. University of St Andrews, UK.
Hack, F., Coram, A., Filún, D. and Heinrich, S. in prep. Occurrence trends and foraging activity of the Chilean dolphin (Cephalorhynchus eutropia), using passive acoustic monitoring, at Isla Chiloé, Chile.
Heinrich, S., 2021. First region-wide estimates of population size and status of endemic Chilean dolphins in southern Chile. IWC final report, https://iwc.int/population-endemic-chilean-dolphins-southern-chile
Heinrich, S. and Espinosa-Miranda, C. 2019. Counting needles in a complex haystack – first abundance estimates for endemic Chilean dolphins in northern Patagonia, Chile. World Marine Mammal Conference (SMM & ECS), Barcelona, Spain. December 2019. (Oral presentation).
Heinrich, S., Genov, T., Fuentes Riquelme, M. and Hammond, P. S. 2019. ‘Fine-scale habitat partitioning of Chilean and Peale’s dolphins and their overlap with aquaculture.’ Aquatic Conservation: Marine and Freshwater Ecosystems 29:212-226.
Heinrich, S. and Reeves, R. 2017. Cephalorhynchus eutropia. The IUCN Red List of Threatened Species 2017: e.T4160A50351955. https://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T4160A50351955.en. Accessed on 10 June 2022.
Heinrich, S. 2006. Ecology of Chilean dolphins and Peale’s dolphins at Isla Chiloé, southern Chile. Ph.D. thesis. University of St Andrews, St Andrews, UK. http://hdl.handle.net/10023/365.
Heinrich, S., Fuentes, M., Zuniga, N., Strange, S. and Espinosa-Miranda, C. in prep. Region-wide abundance estimates for local populations of Chilean dolphins in northern Patagonia, Chile.
Hucke-Gaete, R., L. Bedriñana-Romano, J. Acevedo, F. Viddi, S. Buchan, W. Sielfeld, A. Aguayo-Lobo, P. Zárate, I. Cari, A. Zerbini and J. Redfern. 2022. Diseño para la estimación poblacional de cetáceos en aguas jurisdiccionales de Chile, FIPA 2021-18. Pre-Informe final. Fondo de Investigación Pesquera y de Acuicultura, Subsecretaría de Pesca y de Acuicultura. Unpublished report. 229 pp.
Pérez-Alvarez, M.J., Olavarría, C., Moraga, R., Baker, C.S., Hamner, R.M. and Poulin, E. 2015. ‘Microsatellite Markers Reveal Strong Genetic Structure in the Endemic Chilean Dolphin.’ PLoS ONE 10(4): e0123956. Available at: DOI: 10.1371/journal.pone.0123956.
Pérez-Alvarez, M.J., Espinosa-Miranda, C., Santos-Carvalllo, M., Heinrich, S., Olavarría, C., Sepúlveda, M., Estévez, R., Gelcich, S. “Evaluación de la interacción entre el delfín chileno (Cephalorhynchus eutropia) y actividades de pesca costera y acuicultura a lo largo de su distribución: Fase 1”. FIPA 2018-41-PARTE 1. Pre-Informe final. Fondo de Investigación Pesquera y de Acuicultura, Subsecretaría de Pesca y de Acuicultura. Unpublished 264pp.