Laguna San Rafael IMMA

Criterion A – Species or Population Vulnerability

Chilean dolphins (Cephalorhynchus eutropia) are endemic to south-central and southern Chile and are listed as Near Threatened on the IUCN Red List (Heinrich and Reeves, 2017). Overall abundance is not known but the species is thought to number in the low thousands which, if confirmed, would meet the criteria for Vulnerable status (Heinrich and Reeves, 2017). Chilean dolphins in the southern fjord region are considered genetically distinct from those along the open coast to the north of Chiloé (Pérez-Alvarez et al., 2015). The exact genetic boundary remains unclear due to a 500 km gap in sampling locations. Chilean dolphins have become entangled and drowned in the nets of open-pen fish farms that abound in the region where the IMMA is located (Espinosa-Miranda et al, 2019) . Regular bycatch of only a few individuals could have negative effects on the small local dolphin population estimated to be around 100 individuals  (Heinrich, 2021, Heinrich and Espinosa-Miranda, 2019).

Criterion B: Distribution and Abundance

Sub-criterion B1: Small and Resident Population

A small population of Chilean dolphins has been documented in Laguna San Rafael and the adjacent Esteros Elefante and Cupquelán since at least 2000 (Hoelzel et al. 2003, Viddi et al., 2010). In 2018, the population was estimated at 98 adult individuals (C.I. 82-119) using mark-recapture photo-identification methods (Heinrich, 2021, Heinrich and Espinosa-Miranda, 2019). Chilean dolphins use the inside waters of the lagoon as well as the shallows of Bajo Porvenir and the bays of Esteros Elefante and Cupquelán for foraging, socialising and resting. Mother-calf pairs have been observed throughout the entire IMMA area including inside the ice-filled lagoon. Several salmon farms overlap with Chilean dolphin habitat outside the lagoon. At least one Chilean dolphin became entangled and drowned in a salmon farm net in Estero Cupquelán (Espinosa-Miranda et al., 2020).

Criterion D: Special Attributes

Sub-criterion D1: Distinctiveness

Chilean dolphins in the fjord region south of Puerto Montt (and including Laguna San Rafael) are considered genetically distinct from those along the open coast in the northern portion of the species’ range (Pérez-Alvarez et al., 2015). The exact boundary between the genetically distinct populations is not clear but genetic samples obtained in the IMMA showed clear differences to those obtained north of Chiloé (Pérez-Alvarez et al., 2015). Various research groups have reported extra-limital sightings of Commerson’s dolphins in the Laguna San Rafael area (F. Viddi , C. Olavarria pers. comms) with possible hybridisation with Chilean dolphins (Heinrich, pers. Obs.). These sightings of Commerson’s dolphins are more than 1,000 km north of the species’ usual Pacific range in the Magellan Strait.

A small number of leopard seals have been seen in Laguna San Rafael since at least the late 1970s (Aguayo-Lobo et al. 2011) and they have been sighted so regularly that individuals hauled out on the ice have become a major attraction to the tourist vessels visiting Laguna San Rafael. In 2013 a recently born leopard seal pup was seen on the ice with its mother (Boop, 2014). Vagrant individual leopard seals are observed occasionally along the length of the Chilean coast. However, Laguna San Rafael is one of only two locations along the Pacific coast and outside of the Antarctic where leopard seals are seen regularly and where pups have been born (Acevedo et al., 2016).

Since 2018, several Southern elephant seals have also been observed to haul-out and moult in small numbers on beaches inside Laguna San Rafael (Donke and Segura, 2019). The nearest colony of Southern elephant seals is located about 1,000km further south in Golfo Almirante Montt near the Magellan Strait (Capella et al., 2017).

The wider IMMA area outside of Laguna San Rafael area is also used by Peale’s dolphins (Lagenorhynchus australis), Burmeister’s porpoises (Phocoena spinipinnis), sei whales (Balaenoptera borealis schlegelii), South American sea lions (Otaria byronia) and marine-living river otters (Lontra provocax). Not enough research has been undertaken in this area to assess the importance of the IMMA area for those species. However, this IMMA is the only area in the world where those diverse lineages of marine mammals (and marine living river otters) co-occur.