|Scientific Name:||Otaria byronia|
|Species Authority:||(de Blainville, 1820)|
Otaria flavescens (Shaw, 1800)
Phoca byronia de Blainville, 1820
Phoca flavescens Shaw, 1800
|Taxonomic Notes:||The specific name for the South American Sea Lion has been the subject of much debate. Two names are in current use: Otaria bryonia (based on the type for Phoca bryonia de Blainville, 1820) and O. flavescens (based on the type for P. flavescens Shaw, 1800) (Brunner 2004, Berta and Churchill 2011). According to Brunner (2004), while the locality for de Blainville's specimens is given as Tinian (in the Northern Mariana Islands in the Pacific), the consensus is that this was a mistake and that the specimens were most probably from the Falkland Islands which de Blainville visited on the same trip. According to Brunner (2004), de Blaineville's specimen is without doubt a South American Sea Lion based on the palate description, while the identity of Shaw's specimen (an undescribed skull) remains uncertain and it could have been from a light coloured Arctocephalus species e.g. A. gazella. Thus, despite early arguments that the name O. flavescens had priority (see Rice 1998), the earliest available name applicable with certainty in terms of identification is O. bryonia, hence that name is used here (both names have been used in the past for historical assessments on The IUCN Red List).|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Reviewer(s):||Kovacs, K.M. & Lowry, L.|
Population numbers are high for most of the distribution range and trends are positive for some of the most important local populations. Thus, globally the South American Sea Lion should remain classified as Least Concern. However, it should be noted that the sea lions in Peru are apparently recovering from a strong El Niño event of 97/98 and the Chilean population is in decline.
IUCN Evaluation of the South American Sea Lion, Otaria byronia
Prepared by the Pinniped Specialist Group
A. Population reduction Declines measured over the longer of 10 years or 3 generations
A1 CR > 90%; EN > 70%; VU > 50%
Al. Population reduction observed, estimated, inferred, or suspected in the past where the causes of the reduction are clearly reversible AND understood AND have ceased, based on and specifying any of the following:
(a) direct observation
(b) an index of abundance appropriate to the taxon
(c) a decline in area of occupancy (AOO), extent of occurrence (EOO) and/or habitat quality
(d) actual or potential levels of exploitation
(e) effects of introduced taxa, hybridization, pathogens, pollutants, competitors or parasites.
No integrated counts are available. Generation time is roughly estimated to be 7 years. Populations are declining in Chile and increasing in the Argentine northern Patagonian coast. The population in Peru is fluctuating strongly due to El Niño, with counts that oscillate almost on an annual basis. Pup production is negligible in Uruguay and the Falklands/Malvinas, where significant population reductions have been reported in the Islands, compared to data for the 1930s. The causes of the population declines have not ceased (e.g., El Niño in Peru) but the degree of the declines are apparently lower than required for classification as Vulnerable by IUCN.
A2, A3 & A4 CR > 80%; EN > 50%; VU > 30%
A2. Population reduction observed, estimated, inferred, or suspected in the past where the causes of reduction may not have ceased OR may not be understood OR may not be reversible, based on (a) to (e) under A1.
A population reduction almost certainly happened in the past due to hunting, but this has been discontinued. In Chile hunting was permitted until recently. There is currently a 5-year suspension, but harvesting may be resumed after this time.
A3. Population reduction projected or suspected to be met in the future (up to a maximum of 100 years) based on (b) to (e) under A1.
A population reduction is not suspected at the species level, but there is no data on the potential effect of climate warming.
A4. An observed, estimated, inferred, projected or suspected population reduction (up to a maximum of 100 years) where the time period must include both the past and the future, and where the causes of reduction may not have ceased OR may not be understood OR may not be reversible, based on (a) to (e) under A1.
A population reduction has been observed locally and inferred globally in the past, but not recently.
B. Geographic range in the form of either B1 (extent of occurrence) AND/OR B2 (area of occupancy)
B1. Extent of occurrence (EOO): CR < 100 km²; EN < 5,000 km²; VU < 20,000 km²
The EOO is > 20,000 km².
B2. Area of occupancy (AOO): CR < 10 km²; EN < 500 km²; VU < 2,000 km²
The AOO is > 2,000 km².
AND at least 2 of the following:
(a) Severely fragmented, OR number of locations: CR = 1; EN < 5; VU < 10
(b) Continuing decline in any of: (i) extent of occurrence; (ii) area of occupancy; (iii) area, extent and/or quality of habitat; (iv) number of locations or subpopulations; (v) number of mature individuals.
(c) Extreme fluctuations in any of: (i) extent of occurrence; (ii) area of occupancy; (iii) number of locations or subpopulations; (iv) number of mature individuals.
C. Small population size and decline
Number of mature individuals: CR < 250; EN < 2,500; VU < 10,000
The number of mature individuals is > 10,000.
AND either C1 or C2:
C1. An estimated continuing decline of at least: CR = 25% in 3 years or 1 generation; EN = 20% in 5 years or 2 generations; VU = 10% in 10 years or 3 generations (up to a max. of 100 years in future)
C2. A continuing decline AND (a) and/or (b):
(a i) Number of mature individuals in each subpopulation: CR < 50; EN < 250; VU < 1,000
(a ii) % individuals in one subpopulation: CR = 90–100%; EN = 95–100%; VU = 100%
(b) Extreme fluctuations in the number of mature individuals.
D. Very small or restricted population
Number of mature individuals: CR < 50; EN < 250; VU < 1,000 AND/OR restricted area of occupancy typically: AOO < 20 km² or number of locations < 5
Does not apply.
E. Quantitative analysis
Indicating the probability of extinction in the wild to be: Indicating the probability of extinction in the wild to be: CR > 50% in 10 years or 3 generations (100 years max.); EN > 20% in 20 years or 5 generations (100 years max.); VU > 10% in 100 years
There has been no quantitative analysis of the probability of extinction.
Listing recommendation — Currently, this species should be classified as Least Concern. But, it should be noted that declines in some populations in the Pacific linked to causes that may be aggravated in the future, suggest that the species may soon qualify for a classification of NT.
|Range Description:||South American Sea Lions are widely-distributed, occurring more or less continuously from northern Peru south to Cape Horn, and north up the east coast of the continent to southern Brazil. They also occur in the Falkland/Malvinas Islands. The northernmost breeding distribution on the Pacific side is Isla Lobos de Tierra (6º26’S; Peru). No breeding colonies occur in Brazil. The northernmost breeding rookery in the Atlantic is Isla de Lobos, on the Uruguayan coast.
South American Sea Lions are primarily a coastal species, found in waters over the continental shelf and slope; they occur only infrequently in deeper waters. This species ventures into fresh water and can be found around tidewater glaciers and up rivers. Vagrants have been found as far north as 13°S, near Bahia Brazil and in the Galápagos Archipelago (Ecuador).
Native:Brazil; Chile; Falkland Islands (Malvinas); Peru; Uruguay
|FAO Marine Fishing Areas:||
Atlantic – southwest; Pacific – southeast
|Range Map:||Click here to open the map viewer and explore range.|
The total global population is estimated to be over 250,000. In the Atlantic: about 12,000 in Uruguay (1,200 pups per year), no less than 100,000 in continental Argentina, 6,000 in the Falklands-Malvinas. In the Pacific: 90,000-100,000 in Chile, 60,000 in Peru.
Trends are increasing in northern Argentine Patagonia at 5.7% (Dans et al. 2004) and decreasing in Uruguay (4%; Paez 2005) and Chile (16%). Estimates for southern Patagonia (Santa Cruz and Tierra del Fuego Provinces) show a decrease to only 14.5% of the population size reported in the late 1940s. Sealing activities, performed mainly at northern Patagonia and at Tierra del Fuego, are likely responsible for the depletion (Schiavini et al. 2004). Present population in the Falklands-Malvinas represents about 10% of historical numbers at this locale.
The Peruvian population was decimated by the 97/98 El Niño, from ca. 144 000 animals in 1997 to 28 000 during 97/98 (Arias-Schreiber and Rivas 1998, Arias-Schreiber 1998). The population in 2004 was 60 000, a decrease of 25% from the 2003 numbers. Pup production in Peru declined 48% from 2003 to 2004. This population is apparently recovering. However, the stronger and more frequent El Niños that appear to be occurring along the Peruvian coast may put the vulnerable South American Sea Lion population in Peru at greater risk (Soto et al. 2004).
Genetic studies suggest one population of South American Sea Lions extends through Uruguay, continental Argentina and the Falklands/Malvinas Islands (Szapkievich et al.1999, Freilich 2004).
|Habitat and Ecology:||
South American Sea Lions are stocky, heavy-bodied otariids that are strongly sexually dimorphic. Adult males reach 2.6 m in length and weights of 300 to 350 kg; females reach 2 m and 144 kg. At birth, pups are 11-15 kg and 75-85 cm long. Pups are born black above and paler below, often with grayish orange tones on the undersides. Pups undergo their first moult approximately 1-2 months after birth, becoming dark brown. This colour fades during the rest of the first year to a pale tan to light brown, with paler areas on the face.
The age of attainment of sexual maturity is 4 years for females and 5-6 years for males. Gestation lasts about one year. Longevity is considered to be about 20 years. Mortality rates for adults are unknown (Reijnders et al 1993). Pup mortality estimated for some Peruvian colonies ranged from 13% before El Niño to 100% during El Niño and was negatively correlated with prey availability (Soto et al. 2004).
The start of the breeding season varies somewhat by location and latitude, with pups being born slightly earlier at more southern rookeries. At most sites, both sexes arrive in mid-December with peak numbers of males ashore just after mid-January and peak numbers of females ashore from mid to late January. Females give birth 2-3 days after their arrival at the rookeries; pups are born from mid-December to early February with a peak in mid-January, coinciding with the timing of peak numbers of females ashore. Estrous occurs 6 days after parturition, and females make their first foraging trip 2-3 days after estrous. From this point on, a cycle of foraging and pup attendance starts and lasts until pups are weaned at 8-10 months old. As is the case for many sea lions, it is not unusual for females to continue to care for a yearling while they are nursing a new pup. Pups gather in large pods on the rookeries while waiting for their mothers to return from 1-4 day long foraging trips. Females usually stay ashore for 2 days between trips.
South American Sea Lions are a highly polygynous species with various strategies employed by males and females during the breeding season that are driven by substrate and terrain at the rookery and thermoregulatory requirements imposed by weather conditions at the site. Adult males tend to establish territories through vocalizing, posturing, and fighting, when rookeries provide shade, have tidal pools that can be used for cooling, or funnel interior areas through narrow beaches between rocks or ledges to the sea. At more homogeneous locations with long shorelines, the male strategy focuses on identifying, defending and controlling individual cows in estrous, wherever they are found. Bulls actively and aggressively work to keep estrous cows close to them by grabbing, dragging, and throwing them back inland, away from the shoreline.
At sea, South American Sea Lions frequently raft alone or in small to large groups. They have been reported in association with feeding cetaceans and seabirds. The mean depth of lactating female foraging dives is about 61 m and the mean duration is just over 3 minutes. The maximum depth recorded for a dive is 175 m and duration 7.7 minutes. Two tagged adult males foraged on the continental shelf prior to the onset of breeding, making 5-6 day trips that covered an average of 600 km before they returned to land to haul-out. Dive depth and length are unknown for males, but these two animals spent about 90% of their time in water depths of 50-100 m.
South American Sea Lions are considered non-migratory, although some may wander long distances away from rookeries during the non-breeding season, and some southerly locations such as the Falkland/Malvinas Islands are largely abandoned during the winter. However, most rookeries are continuously occupied by at least some animals, and the species has been described as sedentary. Animals that reproduce at Península Valdés (northern Argentine Patagonia) move to Uruguay and vice versa (Szapkievich et al. 1999).
South American Sea Lions are opportunistic feeders that take a wide variety of prey that varies by location. Their diet includes many species of benthic and pelagic fishes and invertebrates, some of them of commercial value. Forty-one prey species (including fishes, cephalopods, crustaceans, gastropods, polychetes, sponges, and tunicates) were identified in stomach contents of individuals found dead on beaches and from animals recovered in incidental catches of the fisheries of the Patagonian continental shelf (Koen Alonso et al. 2000). Most important items were Argentine Hake (Merluccius hubbsi), Red Octopus (Enteroctopus megalocyathus), Argentine Shortfin Squid (Illex argentinus), "raneya" (Raneya brasiliensis), Patagonian Squid (Loligo gahi) and Argentine Anchovy (Engraulis anchoita). Differences in diet were found between sexes. Females fed mostly on benthic species, whereas males fed mostly on demersal-pelagic species.
Diet and maternal care patterns reflect inter-annual fluctuations in food availability. In the unpredictable Peruvian upwelling ecosystem, females appeared to adjust their diets and maternal attendance patterns in response to annual changes in the abundance and distribution of prey (Soto et al. 2006). Short times onshore nursing and long times at sea foraging are observed during El Niño in Peru, when prey is not abundant near the rookeries. A larger diversity of prey species (particularly of demersal fishes) are consumed during El Niño, when anchovy and lobster are less available. These observations suggest that South American Sea Lions may be good indicators of relative changes in the distribution and abundance of marine resources.
A small percentage of adult male South American Sea Lions regularly prey on South American Fur Seals, although many that pass by colonies investigate the nearby waters and may attempt to capture a fur seal. Adult male sea lions hunt alone and focus their attacks on fur seal pups and juveniles, which are consumed when caught. This has been observed in almost the entire distribution range. About 17% of attacks are successful, but success varies widely between individual males. Subadult males also attack fur seals, but tend to abduct fur seals to serve as female sea lion substitutes, herding them and attempting to mate with them, usually killing them in the process. Female and juvenile sea lions have not been recorded to hunt fur seals. Sea lions have been observed killing young Southern Elephant Seals in the Falkland Islands. They are also known to take several species of penguins, but the importance of penguins in the diet is unknown.
Predators include Killer Whales, sharks and Leopard Seals, and possibly the Puma. At one now-famous rookery (Punta Norte at Península Valdés), Killer Whales are known to surf in on waves, partially beaching themselves while grabbing predominantly young sea lions off the shoreline. Puma tracks have been observed on a rookery in Patagonia and remains of sea lions have been found in a cave used by a Puma in the area.
South American Sea Lions were hunted by native people of South America for thousands of years and have been taken by Europeans as early as the 16th century for food, oil and hides (Rodriguez and Bastida 1998). During the second half of the 19th century coastal zones were rapidly colonized by man and by the turn of the century, sea lion rookeries disappeared from part of their range. Dramatic declines were not only due to spatial competition with man, but also to the indirect effect of pinniped over-exploitation in other areas of the south-western Atlantic. Significant commercial harvests occurred in several countries and sea lion numbers were drastically reduced in the last several hundred years.
The species interacts regularly with fisheries that use a variety of fishing gear and target coastal and pelagic species (Corcuera et al. 1994, Crespo et al. 1994, Sepulveda et al. 2007). During the 1990s, mortality in the fisheries of the Patagonian shelf varied from 150-600 sea lions per year (Crespo et al. 1997, Dans et al. 2003). There is competition with some fisheries (Koen Alonso et al. 2000) and in the case of the Argentine Hake, Merluccius hubbsi, and Argentine Squid, Illex argentinus, interactions may be detrimental at a high level of harvest of the target populations (Koen Alonso y Yodzis 2005).
A longstanding competition for fish has existed in Chile between the South American sea lion and small-scale fisheries. Sea lions, according to fishermen, prey on fish caught in their fishing gear, often causing damage. However, a study of the operational interactions suggests that sea lions do not produce a significant effect on variations in the CPUE obtained by artisanal fishermen (Sepulveda et al. 2007). Sea lions were taken in Chile decades ago for use as bait in crab fisheries. The species is poached in fishing farming operations. Interactions between sea lions and salmon farms in southern Chile are common. No relation was demonstrated between the intensity of attacks and the distance to the nearest colony. Anti-predator nets result in permanent reductions in sea lion attacks (Sepulveda and Oliva 2005).
Intensive trawl fishing for several species in the coastal waters of the southwestern South Atlantic has been implicated in a severe decline of sea lions in the Falkland-Malvinas Islands, where the population has fallen from 30,000 in the 1960s to approximately 15,000 in the 1980s, and possibly to as low as 3,000 in the 1990s.
|Conservation Actions:||South American Sea Lions are protected and managed by laws in most of the countries where they occur. Sea lions have also been afforded protection by the establishment of numerous reserves and protected areas at rookeries and haul out sites, especially in Argentina. However, enforcement of protection regulations is weak in most of the distribution range, particularly in the most isolated areas and at sea. In Chile the species is subject to exploitation. Since 2004 and for five years there has been a moratorium that could be lifted if the interaction with fisheries is shown to be detrimental to the fisheries.|
|Citation:||Campagna, C. 2014. Otaria byronia. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 05 August 2015.|
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