Northern Patagonian Gulfs and Valdes Front IMMA
Size in Square Kilometres
44 582 km2
Qualifying Species and Criteria
South American sea lion – Otaria byronia
Criterion B (1); C (1)
Southern elephant seal – Mirounga leonina
Criterion B (1); C (1, 2)
Southern right whale – Eubalaena australis
Criterion B (1); C (1)
Dusky dolphin – Lagenorhynchus obscurus
Criterion C (2)
Common dolphin – Delphinus delphis
Criterion C (2)
Killer whale – Orcinus orca
Criterion B (1); C (2)
Common bottlenose dolphin – Tursiops truncatus truncatus
Criterion B (1); C (2)
Lahille´s Bottlenose dolphin – Tursiops truncatus gephyreus
Criterion A; B (1); C (2)
South American fur seal – Arctocephalus australis
Criterion C (2)
Marine Mammal Diversity
Criterion D (2)
Otaria byronia, Mirounga leonina, Eubalaena australis, Lagenorhynchus obscurus, Delphinus delphis, Orcinus orca, Tursiops truncatus truncatus, Tursiops truncatus gephyreus, Arctocephalus australis
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Summary
This IMMA includes habitat that supports at least 11 marine mammal species, including both pinnipeds and cetaceans. In the austral winter and spring, it serves as an important area for mating, calving and nursing for southern right whales (Eubalaena australis). The IMMA is also home to resident populations of fewer than 250 Lahille´s bottlenose dolphins (Tursiops truncatus gephyreus) and 30 Killer whales (Orcinus orca). Northern Patagonian coastal areas host over 20 South American sea lion (Otaria byronia) colonies, with an estimated population of 63,000 and pupping occurring between mid-December and February each year. The IMMA also contains important rookeries for Southern elephant seals (Mirounga leonina), with around 15-16,000 pups born every year.
Description of Qualifying Criteria
Criterion A – Species or Population Vulnerability
The IMMA hosts a resident population of Lahille’s bottlenose dolphins (Tursiops truncatus gephyreus), which are classified as Vulnerable on the IUCN Red List (Vermeulen et al. 2019). Fewer than 250 are thought to be present in the IMMA based on average numbers of sightings since the 1970’s (Coscarella et al. 2012). The estimated abundance of Lahille’s bottlenose dolphins in Argentine waters is less than 1000 mature individuals, across at least two genetically distinct subpopulations (Vermeulen et al. 2017, Vermeulen et al. 2019, Loizaga et al. 2020). The cause of this decline is unknown (Coscarella et al. 2012).
Criterion B: Distribution and Abundance
Sub-criterion B1: Small and Resident Populations
There are small and resident populations of both common bottlenose dolphins (Tursiops truncatus truncatus) and Lahille’s dolphins (T.t. gephyreus) in Golfo San Matías, with the latter proven to be genetically isolated from other neighbouring populations (Fruet et al. 2014).
Approximately, 30 killer whales (Orcinus orca) inhabit this IMMA year-round, and the matrilineal lines of the different pods had been identified by means of photo identification (for more information see Punta Norte Research), as well as the individuals that perform the intentional stranding while hunting for southern sea lions. (López and López 1985, Iñíguez 1990, 2001; Hoelzel 1991, Reyes and García-Borboroglu 2004, Sironi et al. 2008, Vila et al. 2008, Coscarella et al. 2015).
Sub-criterion B2: Aggregations
The IMMA harbours temporal aggregations of multiple different marine mammal species. These include at least 21 permanent rookeries and haul-out colonies of South American sea lions (Otaria byronia), representing about 120,700 individuals in breeding and non-breeding colonies (Cardenas Alayza et al. 2015). Southern elephant seals (Mirounga leonina) occupy all of the coast of Península Valdés and the area to the south of the mouth of Golfo Nuevo for their breeding and moulting seasons (Crespo et al., 2007). Over the past 10 years, this species has increased at a rate that appears to be reaching carrying capacity (Ferrari et al. 2013). An estimated, 2,200 southern right whales (Eubalaena australis) congregate in the IMMA between April and December to mate, calve and nurse their young (Crespo et al., 2019).
Criterion C: Key Life Cycle Activities
Sub-criterion C1: Reproductive Areas
The area is a significant breeding ground for Southern right whales, who use the nearshore waters of all three bays of this IMMA between April and December each year to mate, calve and nurse young. These waters are especially important for mothers and calves seeking protection and rest in shallow water (Arias et al. 2018, Crespo et al. 2019, Rowntree et al. 2020). When research on this population first began in 1999, roughly 150 calves were documented per year (Crespo et al. 2018). Between 2005 and 2011, recorded calves peaked at an average of 500 (Crespo et al. 2019). However, the number of calves born each year is variable. In 2018 the number of calves recorded in one season increased to 710, while in 2019 the number was 448 and in 2022 the number was 390 (Crespo et al. 2023).
South American sea lions inhabit northern Patagonia where they are concentrated in 21 colonies (Crespo et al. 2021) that hold an estimated 63,000 individuals. Males and females arrive to the breeding colonies in mid-December, with a maximum number of individuals on land during the second half of January. Females give birth to a single pup 2-3 days after their arrival at the rookeries and remain onshore to breed for approximately 7 days. Pups are born from mid-December to early February, with a peak in mid-January (Crespo et al. 2021).
A large proportion of the Península Valdés coastline is also occupied by approximately 20,000 southern elephant seals that give birth to 15-16,000 pups between September and October every year (Ferrari et al. 2013; Campagna et al. 2021, Lewis and Eder, 2021). They return back to moult between December and May (Crespo et al. 2007).
Sub-criterion C2: Feeding Areas
The Patagonian gulfs provide abundant prey for South American fur seals, Southern elephant seals and common (Delphinus delphis), dusky (Lagenorhynchus obscurus) and Bottlenose dolphins (Koen Alonso et al. 1998, 2000). The most important fish prey species for sea lions, fur seals and dolphins are southern anchovy (Engraulis anchoita), hake (Merluccius hubbs), ‘pampanito’ (Stromateus brasiliensis), and southern cod (Nothotenia sp.). Cephalopods also make up important elements in these marine mammals’ diets, and include the shortfin squid (Illex argentinus), the Patagonian squid (Loligo gahi), sepiolid Semirossia tenera, and octopus (Octopus tehuelchus). Elephant seals feed on deeper waters squid and fish (Daneri & Carlini 2002).
Killer whales also prey in this area on pinnipeds, cetaceans, sea birds and sharks (López and López 1985, Iñíguez 1990, 2001; Hoelzel 1991, Reyes and García-Borboroglu 2004, Sironi et al. 2008, Vila et al. 2008, Coscarella et al. 2015).The pods usually encountered in the area feed on sea lion and elephant seal pups by beaching themselves and returning into the sea during specific periods of the year (Lopez and Lopez, 1985; Hoelzel, 1991, Iñiguez 2001, Vila et al., 2008). Killer whales have been observed hunting dusky (Lagenorhynchus obscurus) and common dolphins (Delphinus delphis) in coordinated attacks where killer whales herd small groups of dolphins towards a ‘catcher’ placed in the path of the dolphins (Coscarella et al 2015). The same killer whales have also been reported training juveniles in these hunting techniques and successfully attacking Southern right whales (Sironi et al., 2008).
Criterion D: Special Attributes
Sub-criterion D2: Diversity
The area includes habitat that supports an important diversity of marine mammal species. At least 11 species, both pinnipeds and cetaceans are regularly documented in the area (Foro para la Conservación del Mar Patagónico y Áreas de Influencia 2013, Falabella 2014). Each year the Northern Patagonian Gulfs (Golfo Nuevo, Golfo San José and Golfo San Matías) are visited by 1000 to 2000 southern right whales (all age classes), out of a total estimated population of 5000 to 6000 individuals. This area is a key breeding and nursery ground for southern right whales, southern elephant seals and South American sea lions. In these waters the resident killer whales have developed intentional stranding, a hunting technique that has cultural transmission. The IMMA hosts a resident population of Lahille’s bottlenose dolphins, which are classified as Vulnerable on the IUCN Red List.
Supporting Information
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