The sea lion is an aquatic mammal found mostly in southern oceans and seas. It is a carnivorous animal that feeds on fish, octopus, and squid. They are long and thick, and despite the differences in size and weight between the sexes, they consume the same amount of food. To learn more about these marine creatures, continue reading.
The sea lion
The South American sea lion (Otaria flavescens) is a type of marine pinniped mammal belonging to the family Otariidae, which is why they are also known as otarines. They resemble seals but are heavier. They inhabit a large portion of the world's oceans and seas, where they feed on fish, octopus, squid, shrimp, and other marine life. For more information about their habitat, see this link about marine biomes.
Some of them are simply called “wolves”, but others have very particular names such as funny sea lion, one-hair sea lion, southern sea lion, South American sea lion or simply sea lion.
Description
They are dark brown in color as adults, but black in their youth. Adult males typically weigh about 300 kilograms, which is twice the weight of females. They have a reddish-brown layer of fur above their necks, which is why they are called "sea lions."
They live in groups of about 15 individuals, consisting of the male, his harem, and a few young. Throughout the summer, in December and January, they travel to protected areas where thousands of individuals gather to give birth. Their gestation period can last almost a year, resulting in a single offspring.
Throughout the breeding season, males usually fight for territory and females, and it is normal for them not to consume food during that time. Its life can be prolonged for about 25 to 50 years. Sea lions are known as a very territorial species.
Food
Their diet typically includes fish, octopuses, squid, penguins, and other seabirds. They consume 15 to 25 kilograms of food per day and are also hunted by orcas and sharks. For more details on the diet of marine animals, you can read this article about what marine animals eat.
The common sea lion is an essential species of the coastal ecosystem, where it moves considerably across the continental shelf. However, females usually travel farther along the coast than males. Their diet was studied in northern and central Patagonia and was based on the identification of otoliths (solid remains used to determine the age of a fish), fish, and cephalopod beaks obtained from their stomach contents.
Among the most important prey items were hake (Merluccius hubbsi), common squid (Illex argentinus and Doryteuthis gahi), squid (Illex argentinus and Doryteuthis gahi) and octopus (Octopus tehuelchus and Enteroctopus megalocyathus). Also included are the anchovy (Engraulis anchoita), the nototenias (Patagonotothen cornucola and P. ramsayi), the sea salmon (Pseudopercis semifasciata), the pollock (Genypterus blacodes), and various elasmobranchs. Among the crustaceans, several species were found, but they are not relevant, except in years of profusion of shrimp (Pleoticus muelleri).
Based on these results, it is inferred that the common wolf is an opportunistic variety that takes advantage of a wide range of resources with a propensity to catch particularly species such as demersal and benthic, some of them of commercial relevance. As part of the parasites of the common wolf, nematodes have been found (Anisakis simplex, Contracaecum ogmorhini, Pseudoterranova decipiens, and Uncinaria sp.); Likewise, the acanthocephalus (Corynosoma australe) and the cestode (Diphyllobothrium pacificum) were obtained.
Habitat
It inhabits the southern coast of South America. In the Pacific Ocean, it is found on the coasts of Peru and Chile; in the Galapagos Islands (Ecuador); and on the Malpelo and Gorgona Islands (Colombia). In the Atlantic Ocean, it lives from the coast of Uruguay to the coasts of the Argentine Sea, both in the continental part of Argentine Patagonia and in the Falkland Islands and the South Sandwich Islands. It is also found in the southern seas of Africa, Australia, and New Zealand.
Danger of extinction
Long ago, they were hunted by humans for their meat and oil, but the primary reason for their hunting today is the use of the skins of their newborn pups, known as "popos" (from the English word "puppy"), in the fur industry. Although their direct exploitation in Patagonia has been banned, fur seals interact with all kinds of fisheries in a wide variety of ways. Throughout the 1990s, significant mortality rates were estimated in various types of bottom and pelagic trawling.
Total annual mortality ranged between 150 and 600 individuals. It also interacts with gillnet fisheries in the Province of Buenos Aires, which target sharks and croakers. It feeds on part of the catch, reducing its economic value, but does not become entangled. It also interacts with longline fisheries in the San Matías Gulf, where it spoils the catch and is subject to persecution by fishermen.
Another type of interaction with fisheries is specific or ecological, which reflects the indirect consequences of fishing exploitation on prey that are common for other predators in the marine ecosystem. Since the sea lion is a well-known and abundant species in the marine system, it is predictable that it interacts with fisheries by consuming prey similar to those of the fishery.
The content of the diet of a predator such as the sea lion is expected to alter as the relative abundances of its potential prey change; particularly considering that hake and common squid are the most relevant prey and also make up the most important target species for fisheries in the area. Therefore, the impact that fisheries have on the abundance of these varieties will end up altering the diet of large predators.
A multispecies model was developed that included common squid, anchovy, hake, and South American fur seals in northern and central Patagonia. The results indicate reciprocal effects between the species included, with the most significant effects being squid and hake harvests, which could negatively influence fur seal populations depending on the intensity of each harvest.
The number of sea lions on the Patagonian coast is expanding even though it has not yet returned to its original population size. The disadvantages of accidental mortality in fishing gear, although they have been previously considered, have not yet been estimated by the fisheries management system. The situation of the accompanying fauna is not part of the assessment system for fishery resources and in the on-board observer programs only issues related to the target species are assessed.
Regarding tourism, while it cannot be considered a threat or a conservation issue, as mentioned above, the new sea lion settlements are located in privately exploited areas, with little protection or oversight by wildlife conservationists or the protected area management system.
Varieties of the Sea Lion
The otarine family, better known as sea lions, is found across different parts of the planet. Below, we'll give you details about each species and its natural environment.
Australian and South African Fur Seal
Scientifically known as Arctocephalus pusillus, it can be found along the Australian coast, particularly in the Bass Strait Islands, and along the South African coast, specifically in Namibia. It is a very peaceful and sociable animal, very friendly in the water, and loves to accompany divers to depths of 60 meters. On land, it usually appears somewhat nervous and fearful in the presence of humans.
South American Sea Lion
The Otaria flavescens of this region are given different names, such as sea lion of a hair or seal of Patagonia. It populates the Pacific and southern Atlantic coasts of South America and can be found in Ecuador, Chile, Argentina and Uruguay. The South American sea lion is dark brown in color, the males weigh about 300 kilos, twice the females, and they are recognized by having a layer of reddish hair on their neck. They live in colonies made up of a male and his harem of females, and have the company of young specimens.
Galapagos Sea Lion
It is also known as the Galapagos fur seal, its scientific name being Arctocephalus galapagoensis. It is an endemic species of the Galapagos Islands in Ecuador and does not migrate. Its diet consists of deep-water fish during the day, and at night it feeds on those that approach the surface. For more information about Galapagos animals , see the corresponding article.
Males are 1,5 meters long and weigh about 65 kilos. Females, on the other hand, are smaller and lighter. This is the smallest species within the family. They are found in reproductive colonies in caves, where the females give birth to only one pup per season.
New Zealand Fur Seal
The Arctophoca fosteri or southeastern fur seal inhabits the southern coast of Australia and the South Island of New Zealand. The territories of males can be located in the Cook Strait and, as an interesting fact, the colonies of Australia and those of New Zealand do not mix with each other, despite being of the same variety.
The males have a weight of about 150 kilos and reach a length of two meters; while the weight of the females is 50 kilos and its length is 1,5 meters. Both sexes show forward-curving hind flippers, pointed nose, and long white whiskers. Its body has a grayish brown color on the back and a lighter color on the belly.
Antarctic Fur Seal
The Arctophoca gazella resides in the Antarctic seas and in the southern seas of Argentina and Chile. The farthest north that they have been seen was in the Kerguelen Islands, located about 2.000 kilometers from Antarctica. When compared to the other members of the family, the shorter snout of the Antarctic fur seal can be noted. On the other hand, the males, which reach two meters in length and weigh up to 230 kilos, show a dark brown skin, while in the females and the young it is gray. Their diet consists of krill and eventually fish.
South American Fur Seal
Its scientific name is Arctophoca australis australis, although it is more commonly known as the two-haired sea lion. It is a species endemic to South America, inhabiting southern Brazil, Uruguay, Argentina, and Chile. Sexual dimorphism is also present in this species, with males being larger than females (two meters and 200 kilos versus 1,5 meters and 60 kilos, respectively).
The diet of this sea lion is made up of crustaceans, cephalopods and fish; it is an animal of opportunity that eats what it gets in the sea. The sea lion is a very popular animal in the southern hemisphere, where it can be seen on the coasts, grouping in colonies among the rocks or on the sandy beaches.
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