Almirantazgo Sound IMMA
Size in Square Kilometres
1 143 km2
Qualifying Species and Criteria
Southern elephant seal – Mirounga leonina
Criterion C (1)
Leopard seal – Hydrurga leptonyx
Criterion C (1)
Commerson’s dolphin – Cephalorhynchus commersonii
Criterion B (1)
Marine Mammal Diversity
Lagenorhynchus australis, Orcinus orca, Cephalorhynchus eutropia
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The Almirantazgo Sound is located between high mountains on the western coast of the Isla Grande de Tierra del Fuego. Glacial melt introduces cold waters to the adjacent fjords and the area is also characterised by strong winds from the west. The area hosts two species of seals, the southern elephant seal (Mirounga leonina) and the leopard seal (Hydrurga leptonyx). The southern elephant seal has a circum-Antarctic distribution, and in the last 50 years two breeding colonies have been registered in the Sound, one in Ainsworth Bay and another in Jackson Creek. These fjord systems provide suitable habitat for the southern elephant seal colonies to breed and nurse their pups. The Parry Fjord supports a leopard seal colony, where pupping has been documented. This fjord is within the pack ice zone, and thus includes habitat similar to the Antarctic waters. Commerson’s dolphins (Cephalorhynchus commersonii) have also established a small resident population in the Almirantazgo Sound, which appears to be isolated from the principal stock of the species on the Atlantic coast.
Description of Qualifying Criteria
Criterion B: Distribution and Abundance
Sub-criterion B1: Small and Resident Populations
Commerson’s dolphins (Cephalorhynchus commersonii) are found in shallow waters mostly along the Atlantic coast of South America, from the Gulf of San José to the tip of Tierra del Fuego of Argentina (Goodall et al., 1988; Goodall, 1994). In Chilean waters, Commerson’s dolphins occur frequently in the eastern area of the Magellan Strait, although small groups have also been observed occasionally inside the Patagonia system. The paucity of records of Commerson’s dolphins inside the fjords and channels to south of 40° S in the Pacific suggests that its occurrence is unusual (Aguayo et al. 2006, Acevedo et al. 2016a). Nevertheless, in Almirantazgo Sound a resident population has been registered since 1995 (Gibbons et al., 2000, Lescrauwaet et al., 2000). According to genetic studies (mitochondrial DNA) the population of Tierra del Fuego in Chile showed significant genetic differentiation with the Atlantic population. The gene flow between local areas is low and also the dispersal rates in both sexes (Pimper et al., 2010).
Criterion C: Key Life Cycle Activities
Sub-criterion C1: Reproductive Areas
Southern elephant seals (Mirounga leonina) are listed as VU(C1) in Chile under the Chilean Regulation for the Classification of Wild Species. This reflects that there are currently few breeding or regular haul-out locations along the Chilean Pacific coast as the species was nearly extirpated in this area due to hunting (Cárcamo et al., 2018). Southern elephant seals in Chile inhabit three main haul-out sites in the Magallanes Region: Ainsworth Bay (54°24′S) and Jackson Creek (54°26′S), both located in Almirantazgo Sound in Tierra del Fuego Island, and the Poca Esperanza Estuary (52°14′S) (Acevedo et al., 2016a, Capella et al., 2017). The presence of southern elephant seals in Almirantazgo Sound has been reported since the 1970s and the population is growing (Acevedo et al., 2016a, Acevedo et al., 2016b). Ainsworth Bay (54°24′S) and Jackson Creek (54°26′S) in Almirantazgo Sound are two of the three northernmost breeding colonies of southern elephant seals in Chile. The population is estimated at around 160 animals, with pupping observed at Ainsworth in 2003 and at Jackson Creek in 2012 (Acevedo et al 2016b). The southern elephant seal populations in Ainsworth Bay and Jackson Creek within this IMMA are probably connected with those colonies in the nearby Atlantic (Hindell et al., 2016, Rodrìguez et al., 2016), which have an estimated population estimation of 67,000 animals in Península Valdés and 1,700 in the South Shetland Islands (Carcano et al., 2018). In Almirantazgo Sound the maximum observed animals are 162 with 19 pups (Acevedo et al., 2016b).
Leopard seals (Hydrurga leptonyx) are widely distributed within the Antarctic pack ice. Recently they have been reported further north, in the fjords of southern Chile, where individuals remain year-round including on Tierra del Fuego Island. Little was known of the leopard seals reproductive biology or breeding distribution, and more specifically, whether they use southern Chilean waters to breed. However, two recent opportunistic sightings of leopard seal adult–pup pairs were observed in Parry Fjord, Almirantazgo Sound, on 2 December 2012 and 6 October 2015 (Acevedo et al., 2017). Although the pups reported here were dead, these records provide further information of rare pupping in South American waters. The habitat in Parry Fjord is similar to the Antarctic waters and pack ice of Antarctica, and thus could provide important breeding habitat for those limited few numbers of the species which reside in the fjords of southern Chile.
Acevedo, J., Aguayo-Lobo, A., Haro, D., Garrido, G., & Olave, C. 2016a. Occurrence of the Commersonʼs Dolphin (Cephalorhynchus commersonii) in Fitz Roy Channel, Pacific Coast of Chilean Patagonia. Aquatic Mammals 45(3): 266-273.
Acevedo, J., Aguayo-Lobo, A., Brito, J.L., Torres, D., Cáceres, B., Vila, A., Cardeña, M. and Acuña, P. 2016b. Review of the current distribution of southern elephant seals in the eastern South Pacific, New Zealand Journal of Marine and Freshwater Research, 50:2, 240-258, DOI: 10.1080/00288330.2015.1132746
Acevedo, J., González, A., Garthe, S., Gonzalez, I., Gómez, R., and A. Aguayo-Lobo. 2017. Birth of leopard seals in southern Chile. Polar Biology 40:713-717.
Aguayo-Lobo, A., Acevedo, J. and Olave, C. 2006. Actualización de las bases para una estrategia para la conservación de mamíferos marinos en la región de Magallanes y Antártica Chilena. Informe Final. Fundación CEQUA.
Capella, J., Toro, F., Kush, A. & Gibbons, J. 2017. New breeding colony of southern elephant seal Mirounga leonina (Linnaeus 1758) (Phocidae) in southern Chile. Anales Instituto Patagonia (Chile), 45(3):87-92.
Cárcamo, D., ·Pizarro, M., · Orellana, M., Muñoz, L., · Pavez, G., · Sepúlveda, M., Durán L.R. &· Oliva, D. 2018. Are southern elephant seals re‑invading mid‑latitude grounds? New sightings and first birth records off the Chilean Coast. Polar Biology, DOI: 10.1007/s00300-018-2433-z
Gibbons, J., Gazitúa, F. & Venegas C. 2000. Cetáceos en el Estrecho de Magallanes y Senos Otway, Skyring y Almirantazgo. Anales del Instituto de la Patagonia 28: 107-118.
Goodall, R. N. P., Galeazzi, A. R., Leatherwood, S., Miller, K. W., Cameron, I. S., Kastelein, R. A., & Sobral, A. P. 1988. ‘Studies of Commerson’s dolphins, Cephalorhynchus commersonii, off Tierra del Fuego, 1976-1984, with a review of information on the species in the South Atlantic’. In R. L. Brownell, Jr. & G. P. Donovan (eds.) Biology of the genus Cephalorhynchus, pp. 3-70. Cambridge, UK: International Whaling Commission.
Goodall, R. N. P. 1994. Commerson’s dolphin Cephalorhynchus commersonii (Lacépède 1804). In S. H. Ridgway & R. Harrison (eds.) Handbook of marine mammals, pp. 241-267. San Diego, CA: Academic Press.
Hindell, M. A., McMahon, C.R., Bester, M. N., Boehme, L., Costa, D., Fedak, M.A., Guinet, C., Herraiz-Borreguero, L., Harcourt, R.G., Huckstadt, L., Kovacs, K.M., Lydersen, C., McIntyre, T., Muelbert, M., Patterson, T., Roquet, F., Williams, G., and Charrassin, J.B. 2016. Circumpolar habitat use in the southern elephant seal: implications for foraging success and population trajectories. Ecosphere 7(5):e01213. 10.1002/ecs2.1213
Lescrauwaet, A-C., J. Gibbons, L. Guzmán & Schiavini, A. 2000. Abundance estimation of Commerson’s dolphin in the eastern area of the Strait of Magallan-Chile. Revista Chilena de Historia Natural 73:473-478.
Pimper, L.E., Baker, C.S., Goodall, R.N.P., Olavarria, C. & Remis, M.I. 2010. Mitochondrial DNA variation and population structure of Commerson’s dolphins (Cephalorhynchus commersonii) in their southernmost distribution. Conservation Genetics 11: 2157–2168. https://doi.org/10.1007/s10592-010-0102-z
Rodríguez, J.P., Fernández-Gracia, J., Thums, M., Hindell, M.A., Sequeira, A.M., Meekan, M.G., Costa, D.P., Guinet, C., Harcourt, R.G., McMahon, C.R., Muelbert, M., Duarte C.M., & Eguíluz, V.M. 2016. Big data analyses reveal patterns and drivers of the movements of southern elephant seals. Scientific Reports | 7: 112 | DOI:10.1038/s41598-017-00165-0
Valdenegro, A. and Silva, N. 2003. Caracterización Oceanográfica Física y química de la zona de canales y fiordos australes de Chile entre el Estrecho de Magallanes y Cabo de Hornos (CIMAR 3 Fiordos). Cienc. Tecnol. Mar, 26 (2): 19-60.