Juan Fernández Archipelago IMMA
Size in Square Kilometres
83 409 km2
Qualifying Species and Criteria
Juan Fernandez fur seal – Arctocephalus philippii
Criterion B (2), C (1, 2)
Marine Mammal Diversity
Mirounga leonina, Arctocephalus tropicalis, Balaenoptera physalus, Balaenoptera musculus, Balaenoptera acutorostrata, Balaenoptera borealis, Balaenoptera edeni, Megaptera novaeangliae, Physeter macrocephalus, Delphinus delphis, Orcinus orca, Tursiops truncatus
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Summary
The Juan Fernández Archipelago includes the islands of Robinson Crusoe (48 km2), Alejandro Selkirk (50 km2), and Santa Clara (2,2 km2). The archipelago is situated 600 km offshore from the Chilean mainland. The surrounding marine environment is characterised by the presence of seamounts and volcanoes, which strongly influence the oceanographic patterns in the area. The Juan Fernandez fur seal (Arctocephalus philippii) is an endemic species of pinniped with a restricted area of distribution, associated in environments characterised by seamount topography and the presence of eddies which generate high primary production. Juan Fernandez fur seals are recovering from intense hunting in the 19th century and have passed a severe genetic bottleneck. Both reproductive processes and the feeding activities occur within this IMMA. The species is categorised as Least Concern (LC) on the IUCN Red List of Threatened Species, with recent exponential growth following the cessation of hunting. The area also hosts a number of other marine mammal species, including both pinnipeds and cetaceans.
Description of Qualifying Criteria
Criterion B: Distribution and Abundance
Sub-criterion B2: Aggregations
The Juan Fernández fur seal (Arctocephalus philippii) is an endemic species with a limited distribution between Desventuradas Island and the Juan Fernández Archipelago. The population is recovering after intense hunting during the 19 nineteenth century. The Juan Fernández Archipelago currently hosts a total of 63 colonies: 47 in Robinson Crusoe, and 8 each in Santa Clara and Alejandro Selkirk Islands (Alvarez, 2019). Between 1965 and 2018, the Juan Fernández fur seal population has been growing exponentially in the three islands of the Archipelago (Dúran et al., 2019). The estimated population for the year 2018 was around 220,000 individuals (Durán et al., 2019), making it the most abundant otariid species in the south east Pacific. During the 1980s and 1990s the species was declared as Vulnerable (VU) on the IUCN Red List of Threatened Species, changing to Least Concern (LC) in 2015 (Aurioles-Gamboa, 2015). However, the limited distribution of the species, the restricted habitat for which it shows preference, the limited breeding space available and the genetic bottleneck through which it passed, are factors that make the Juan Fernández fur seal a species vulnerable to natural disturbances or of anthropic origin (Aurioles-Gamboa, 2015).
Criterion C: Key Life Cycle Activities
Sub-criterion C1: Reproductive Areas
Juan Fernández fur seal reproduction has not been documented anywhere outside of the Juan Fernández Archipelago IMMA (Torres, 1987). In 2018, 19 rookeries were registered in Robinson Crusoe and 6 in Santa Clara Island. The newborn pups comprised 25% of the total population (Durán et al., 2019).
Sub-criterion C2: Feeding Areas
Juan Fernández fur seals have an oceanic diet associated with the Humboldt Current and its diet consists mainly of cephalopods and myctophids (Ochoa & Francis, 1995, Diaz, 2007). The Humboldt squid (Dosidicus gigas) represents the most frequent prey item for females (Diaz, 2007). On the other hand, the myctophid Symbolophorus barnardi and the squid Onychoteuthis banksi have also been identified in the Juan Fernández fur seals diet (Ochoa & Francis, 1995). The presence of this myctophid, which is distributed between 100 and 800 m in the water column, in Juan Fernández fur seal scat contents suggests that the seals are foraging in deep waters within the IMMA. Instrumented animals were documented diving to depths between 88.5 and 169.5 m. For three instrumented females, the mean duration of the foraging trips was 18 days and the mean travel distance was 336 km (Osman, 2007).
Supporting Information
Aguayo, A., Maturana, R., & Torres, D. 1971. El Lobo Fino de Juan Fernandez. Revista de Biología Marina 13(3):135–148.
Alvarez, D., 2019. Cambios en la abundancia poblacional de Arctocephalus philippii en el Archipiélago de Juan Fernández. Tesis para optar al grado de Licenciado en Ciencias, Mención Biología, Universidad de Valparaíso.
Aurioles-Gamboa, D. 2015. Arctocephalus philippii, Juan Fernández Fur Seal. The IUCN Red List of Threatened Species, 12. https://doi.org/http://dx.doi.org/10.2305/IUCN.UK.2015- 2.RLTS.T2059A61953525.
Castilla, J.C. & D. Oliva. 1987. ‘Islas Oceánicas Chilenas: Aspectos descriptivos y potencialidades’. In J.C. Castilla (ed.) Islas Oceánicas Chilenas: Conocimiento Científico y Necesidades de Investigaciones, pp 15-35. Santiago: Ediciones Universidad Católica de Chile.
Diaz, M.P. 2007. Dieta de las hembras de Arctocephalus philippii (Peters, 1866) durante la temporada reproductiva en el Archipiélago de Juan Fernández. Marine Biology Thesis, Universidad Austral de Chile.
Durán, L.R., G. Araya, D. Alvarez, R. Schiller, D. Arredondo, A. Garcia, J. Meza & D. Oliva. 2019. Population recovery of Arctocephalus philippii in the Juan Fernández Archipelago, southeastern Pacific. World Marine Mammal Conference, Barcelona 2019.
Fernández, M. & Hormazábal, S. 2014. Overview of recent advances in oceanographic, ecological and fisheries research on oceanic islands in the southeastern Pacific Ocean. Latin American Journal of Aquatic Research 42(4): 666-672.
Ochoa, H., & Francis, J. 1995. Spring and summer prey of the Juan Fernandez fur seal, Arctocephalus philippii. Canadian Journal of Zoology, 73(8), 1444–1452. https://doi.org/10.1139/z95-170
Osman, L., 2008. ‘Population status, distribution and foraging ecology of Arctocephalus philippii (Petres 1866) at Juan Fernández Archipelago’. Doctoral Thesis. Doctor in Science with mention on Systematic and Ecology by Universidad Austral de Chile. 106 pp.
Thiel M, Macaya EC, Acuña E, Arntz WE, Bastias H, Brokordt K, Camus PA, Castilla JC, Castro L, Cortés M, Dumont CP, Escribano R, Fernandez M, Fajardo JA, Gaymer CF, Gomez I, Gonzalez AE, González H, Haye PA, Illanes JE, Iriarte JL, Lancellotti DA, Luna-Jorquera G, Luxoro C, Manriquez PH, Marín V, Muñoz P, Navarrete SA, Perez E, Poulin E, Sellanes J, Hito Sepúlveda H, Stotz W, Tala F, Thomas A, Vargas CA, Vasquez JA & JM Alonso Vega. 2007. The Humboldt current system of northern and central Chile. Oceanographic processes, Ecological interactions and socioeconomic feedback. Oceanography and Marine Biology: An Annual review 45: 195-344.
Torres, D., 1987. ‘Antecedentes sobre el lobo fino de Juan Fernández, Arctocephalus philippii, y proyecciones para su estudio’. In: J.C. Castilla (ed.). Islas Oceánicas Chilenas: Conocimiento Científico y Necesidades de Investigaciones, pp 287-317. Santiago: Ediciones Universidad Católica de Chile.
