The Sea Otter
The sea otter is a carnivorous marine mammal belonging to the mustelid family. It is considered the only living species in the genus Enhydra and can be found in the North Pacific Ocean, from northern Japan to Baja California in Mexico.
Adult specimens of this species reach a weight of 14 to 45 kilograms, making them the heaviest among mustelids and one of the smallest marine mammals. Unlike other marine mammals, this species' primary form of thermal insulation is an unusually thick layer of fur, the densest of any mammal.
Although they can emerge onto land, the sea otter resides almost exclusively in the sea. They are found near coasts, where they dive to the seabed to forage. Their diet consists primarily of marine invertebrates such as sea urchins, mollusks, crustaceans, and certain fish. Their feeding habits are remarkable in some respects.
The first thing to note is the use of rocks to break the shells of some of its prey, a practice that makes it one of the few mammals that uses tools. On the other hand, in most of its distribution area, it is an essential species due to the control it maintains over the population of sea urchins, which, if not controlled, would cause enormous damage to ecosystems. kelp forests. As part of the otter's diet, fish in high demand by the fishing industry are included, which leads to conflicts between them and fishermen.
The number of specimens of this species, whose original figure was estimated at between 150.000 and 300.000 individuals, was intensively decimated, due to their fur, between 1741 and 1911, until it decreased to only 1.000 or 2.000 otters at that time. An international ban on its hunting, conservation initiatives and reintroduction plans have been of great help in increasing its population. The species now occupies nearly a third of its original range.
The re-establishment of the sea otter has been considered an important milestone in marine conservation, despite the fact that the population of the Aleutian Islands and California has been reduced in recent times or has not increased further. However, for various reasons, including its great fragility in the face of oil spills, the species is still listed as in danger of disappearing.
Taxonomy
The initial scientific description of the sea otter can be found in Georg Steller's field notes of 1751, and it was established as a species by Linnaeus in his book Systema naturae of 1758. The current scientific name Enhydra lutris was coined in 1922; the genus Enhydra comes from the ancient Greek "en" (in) and "hydra" (water), meaning "in the water," and the Latin term lutris, meaning "otter."
Other mustelid species, such as the sea cat, found on the southwest coast of South America, reside primarily in freshwater, but can also be found in coastal marine environments. The now-extinct sea mink, which once inhabited North America, is another mustelid that has adapted to the marine environment.
Evolution
The sea otter is the heaviest member of the Mustelidae family (the giant otter is longer but lighter), a diverse grouping that includes all thirteen otter species and certain land animals such as weasels, badgers, and mink. It is the only mustelid species that does not live in burrows or caves and can spend its entire life underwater.
It is the only living species belonging to the genus Enhydra, but it displays a very distinct appearance from other mustelids, which, until 1982, many scientists believed were more closely related to true seals. DNA tests indicate that the sea otter and its closest relatives, the spotted-necked otter, the European otter, the clawless otter, and the little otter, shared a common ancestor approximately five million years ago.
Fossil evidence indicates that the genus Enhydra became isolated around two million years ago, giving rise to the now extinct Enhydra macrodonta and the still-extant Enhydra lutris. The species initially developed in northern Hokkaido and Russia, later spreading to the Aleutian Islands, Alaska, and the southern coast of North America.
Compared to cetaceans, sirenians, and pinnipeds, which entered the water some fifty, forty, and twenty million years ago respectively, the sea otter is a recent arrival in marine habitats. However, in some respects, this otter has adapted more to aquatic life than pinnipeds, as the latter still emerge onto land or ice to raise their young.
Subspecies
Three subspecies have been recognized, which are distinguished by the size of their bodies and by certain features of their teeth and skull:
- The common sea otter (E. l. lutris Linnaeus, 1758), found from the Kuril Islands to the Commander Islands in the western Pacific, is also known as the Asian sea otter, is the largest subspecies, has a broad skull, and short nasal bones.
- The southern sea otter (E. l. nereis Merriam, 1904) can be found off the coast of Central California. Also known as the California sea otter, it has a narrower skull, an elongated snout, and small teeth.
- The northern sea otter (E. l. kenyoni Wilson, 1991), is found in Alaska and the western Pacific coast from the Aleutian Islands to British Columbia, Washington, and northern Oregon. After being extirpated in southern British Columbia due to overhunting, it has been reintroduced around Vancouver Island and the Olympic Peninsula.
Efforts to reintroduce it to the Oregon coast have been unsuccessful. However, in Washington from 1969 to 1970 a positive result could be obtained with a corresponding increase in its range and population. Today they can be found in the Strait of Juan de Fuca and can be found almost as far as Pillar Point Bay. Certain individuals have been observed in the San Juan Islands and north of Puget Sound.
Physical characteristics
The sea otter is considered one of the smallest marine mammals. Males weigh 22 to 45 kilograms (1,2 to 1,5 pounds) and are 14 to 33 meters (1,0 to 1,4 feet) long. Females are smaller, weighing XNUMX to XNUMX kilograms (XNUMX to XNUMX pounds) and measuring XNUMX to XNUMX meters (XNUMX to XNUMX feet) in length. Unlike other marine mammals, the sea otter lacks a thick layer of blubber and relies on its extraordinarily dense fur for warmth.
With up to more than 150.000 hair filaments per square centimeter, their fur is the densest of all mammals. This coat consists of a long, water-impervious outer layer of hair and a shorter undercoat, where the outer layer keeps the undercoat dry. This coating completely separates cold water from their skin and restricts heat loss. The fur remains thick throughout the year and is constantly replaced instead of undergoing a seasonal shedding.
The ability of the fur to remain impervious to water impacts heat retention, thus requiring thorough cleaning. Given this, the sea otter has the ability to reach and groom all parts of its body, using its extremely movable skin and exceptionally flexible skeleton. Its fur color is usually dark brown with silver-gray markings; however, it can range from yellowish to grayish brown or almost black. In adult specimens, the head, neck, and chest are lighter in color than the rest of the body.
The sea otter has several adaptations for navigating the marine environment. It can close its nostrils and ear canals; its hind limbs, which provide most of its swimming propulsion, are long, broad, and flattened, with webs between the toes. The fifth toe on each foot is the longest, which enhances its swimming ability but hinders its movement on land.
The tail is extremely short, slightly flattened, and very muscular. The forelimbs, shorter than the hindlimbs, have retractable claws with firm pads on the palms that enable it to grasp slippery prey. It propels itself underwater by means of the up-and-down undulating motion of the hind part of its body, including the tail and hindlimbs. It can reach speeds of up to 9 kilometers per hour.
When underwater, its body takes on a long, slender appearance, retaining its short forelimbs tightly clasped over its chest. Upon surfacing, it usually floats on its back and moves using its legs and tail as paddles. When resting, it usually rests all four limbs on its chest to conserve heat. On hot days, it may keep its hind limbs underwater to cool itself.
This otter's body is highly buoyant thanks to its enormous lung capacity, about 2,5 times greater than that of land mammals of similar size, and the air trapped in its fur. The sea otter can walk on its limbs, but with a slow gait, it glides across land, and can run with short hops. Highly sensitive vibrissae (nose hairs) and the pads on its forelimbs help it locate prey by touch in murky water.
Researchers have observed that when approaching otters, they respond more quickly when the wind is in their favor, suggesting that smell is more important than vision as a sense for surveillance. Other assessments indicate that vision is useful both in and out of the water. However, this sense is not as developed as that of seals. Their hearing is not particularly acute or very poor. An adult has 32 teeth, which, primarily the molars, are flattened and rounded, designed for grinding rather than cutting.
Pinnipeds and sea otters are the only carnivorous creatures with two incisors in the lower jaw instead of three; their dental formula is 3.1.3.1 – 2.1.3.2. Otters have a basal metabolic rate two to three times higher than that of land mammals of the same size. They must eat an estimated 25 to 38% of their body weight each day to obtain the calories needed to offset the heat loss caused by the low water temperatures where they live.
Its digestive efficiency is estimated at 80 to 85%, and it digests food rapidly, in as little as three hours. It obtains much of its water requirements from its food; however, unlike other marine mammals, it can also ingest seawater, since its relatively large kidneys are capable of purifying seawater and expelling concentrated urine.
Food
The sea otter's diet consists of more than 100 different prey items. In most of its range, its diet consists almost exclusively of marine invertebrates, including sea urchins, a variety of bivalves such as clams and mussels, abalones, various mollusks, crustaceans, and snails. Their prey ranges in size, from modest limpets and crabs to enormous octopuses. When faced with sea urchins, clams, and abalone of various sizes, they usually prefer the larger prey.
In certain areas in the northern part of their range, they also consume fish. In research conducted on Amchitka Island in the 1960s, where the otter population reached its peak, 50% of the food found in their stomachs consisted of fish. The most frequently found species are bottom-dwelling, slow-moving or slow-moving otters such as Hemilepidotus hemilepidotus and members of the Tetraodontidae family. However, south of Alaska, they show no interest in fish, or they only make up a small proportion of their diet.
Contrary to popular belief, sea otters very rarely feed on starfish, and any algae swallowed apparently passes through their digestive system undigested. Individuals within a given range often differ in their foraging habits and prey types, and they usually follow the same pattern they learned from their mothers.
The diet of local populations also changes over time due to the search for alternatives, as they are able to reduce the supply of their favorite prey, such as sea urchins, and attribute the lack of secondary food to other circumstances, such as human fishing.
Sea otters can extract abalones from an entire area, except for those hidden in rock crevices. However, they never completely exterminate a single species they feed on in a specific location. A 2007 study in California showed that in areas where food is relatively scarce, they were eaten by a wide variety of animals. Surprisingly, however, the diet of each individual was more specialized in these areas than in places where food is abundant.
Behavior
Using its whiskers and forepaws, the sea otter can locate its prey by using its sense of touch. The sea otter is diurnal, foraging in the morning, beginning an hour before dawn, then resting and sleeping at midday. Foraging resumes for a few hours in the afternoon and stops before dusk.
A third foraging period may occur around midnight. Females with pups appear to prefer to eat at night. Tracking the amount of time otters spend eating each day reveals a figure that varies from 24% to 60%, apparently depending on the availability of food in the area.
Each individual spends extended periods of time grooming (about 10% of their time). This cleaning involves detangling and cleaning their fur, removing flaking skin, and rubbing their skin to remove water and bring in air. To a casual observer, it might appear that the creature is scratching itself; however, it is unknown whether lice or other parasites remain on its skin. While feeding, they frequently rotate in the water, apparently with the purpose of removing food debris from their fur.
How do you get your food?
The sea otter catches prey during the brief dives it almost always makes to the ocean floor. Although it can dive for five minutes, its dives usually last around one minute and generally do not exceed four minutes. It is the only marine mammal capable of lifting and turning rocks from the bottom, which it frequently does with its front paws when searching for prey.
They can also separate snails and other organisms stuck to seaweed and dig beneath the muddy bottom in search of clams. They are the only marine mammal that uses their forelimbs to catch fish instead of directly using their teeth. Under each forelimb, the otter has a kind of pocket made of loose skin that extends across the anterior section of its thorax.
In this pouch (primarily the left one), the animal deposits food during its dives to bring to the surface. Once there, it eats while floating on its back, using its forelimbs to select food and direct it to its mouth. It can chew and swallow small mussels complete with shell, but larger animals must have their shells removed.
To separate the meat from the shells, it uses its prominent lower incisors. To feed on sea urchins, which are covered in spines, the otter nibbles at their undersides, where the spines are short, then sucks the contents out of the shell. This animal uses rocks in its feeding process, making it one of the few mammals capable of using tools.
To break hard shells, it pounds its prey, holding it between its front legs. To dislodge abalones (gastropod mollusks) from a rock, it pounds the shell with a large rock, delivering three impacts every second. Dislodging an abalone, which can cling to a rock with a force similar to four thousand times its own body weight, requires numerous dives.
Social structure
Because adults and juveniles are independent and forage independently, otters prefer to rest together in same-sex groups called rafts. These groups are composed of ten to one hundred individuals, with males being larger than females. The largest groups have been observed to number more than two thousand individuals. To prevent them from drifting in the sea while resting and feeding, otters often wrap themselves in seaweed.
A male is quite likely to reproduce if his mating territory is located in an area favored by females. Since the main breeding season occurs in the fall throughout much of their range, males typically guard their territory only from spring to fall. During this season, they prowl the boundaries to keep other males away; however, fights occur very rarely.
Adult females move freely within male territories and outnumber males by a ratio of 5 to 1. Males without their own territories usually congregate in all-male groups and move through female-occupied areas in pursuit of a mate. Sea otters display diverse vocal behavior. A pup's cry is often compared to that of a seagull.
Females appear to murmur when they are happy, while males tend to growl instead. When frightened or distressed, adults tend to hiss, hiss, or, in extreme situations, scream. Although the sea otter is a sociable and playful creature, it is not truly considered a social animal. They spend much of their time alone, and each adult can satisfy its own dietary, hygiene, and defense requirements.
Reproduction and Life Cycle
Sea otters are polygynous, meaning males mate with several partners. However, during the season when females are receptive to the male, they may temporarily form a pair for a few days. Mating takes place in the water and can be violent, with the male biting his partner's snout, often leaving scars on her nose, and sometimes holding her head submerged.
Births occur throughout the year, with a higher incidence from May to June in the northern populations of their range and from January to March in the southern populations. The gestation period apparently ranges from four to twenty months, since the species has a delayed implantation period, with actual gestation occurring only in the last four months. In California, otters breed annually, almost twice as frequently as their Alaskan counterparts.
Births also occur in the water and typically result in a single calf weighing 1,4 to 2,3 kilograms (2 to XNUMX pounds). Twin births occur in XNUMX% of cases; however, usually only one survives. Upon arrival, the pups open their eyes immediately, have ten visible teeth, and are covered in thick fur. Mothers have been observed licking and shaking their pups for hours; after grooming, the fur is able to retain enough air to help the pups float.
The newborn's fur is replaced by that of the adult after thirteen weeks. Lactation lasts six to eight weeks in California otters and four to twenty months in Alaskan otters. Mothers begin providing their pups with bites of food starting at one or two months old. Sea otter milk originates from a pair of teats located on the abdomen and is more similar to the milk of marine mammals than to that of other mustelids.
A pup, guided by its mother, swims and dives for several weeks before reaching the seabed. Initially, the objects it collects from the seabed are of little nutritional value, such as brightly colored starfish and pebbles. The young become independent by the time they reach six to eight months; however, a mother may be forced to abandon her pup if she cannot provide sufficient food, or, in contrast, to care for it until it almost reaches adulthood.
The mortality rate among cubs is high, and most frequently occurs in their first winter. It is estimated that only 25% of them survive their first year. Those born to experienced mothers have the highest survival rates. Females are responsible for all tasks related to feeding and caring for their young; occasionally, they have been seen caring for orphaned cubs. Much has been said about the level of attention mothers show their cubs, providing constant care by carrying them on their chests away from the icy water and meticulously grooming their fur.
When searching for food, they float their young in the water, sometimes wrapped in seaweed, which prevents them from drifting away. If the young are not found asleep, they squeal loudly until they return. Mothers have been known to still carry their young after days of being dead. Females reach sexual maturity at about three or four years of age, and males at five. However, males often do not become reproductively active until several years later. One captive male conceived pups at the age of nineteen.
In the wild, sea otters can live up to a maximum of 23 years, with an average life expectancy of 10 to 15 years for males and 15 to 20 years for females. Some captive specimens have lived past 20 years, and one female kept at the Seattle Aquarium died at 28 years of age. In the wild, they frequently suffer from dental deterioration, which can contribute to a shortened lifespan.
Population and Distribution
Sea otters live in coastal waters with depths between fifteen and twenty-three meters, and they typically stay within a kilometer of the shore. They are most frequently found in areas protected from the strongest ocean winds, such as rocky shorelines, dense kelp forests, and barrier reefs. Although they frequently inhabit rocky substrates, sea otters can also survive in areas where the ocean floor consists of mud, sand, or silt.
Their northern range is limited by the Arctic ice edge, as these creatures can survive on floating ice but cannot on fast ice. Each individual typically occupies a territory several kilometers in size and remains there for a year.
The sea otter population is estimated to number between 150.000 and 300.000, distributed in an arc across the North Pacific from northern Japan to central Baja California, Mexico. The commercialization of their fur, which began in the 1740s, eventually reduced the species' population to just XNUMX or XNUMX individuals spread across XNUMX colonies.
In nearly two-thirds of its former range, the species has shown a changing level of recovery, ranging from high-density populations to threatened populations. Today, stable communities exist in regions along the eastern coast of Russia, Alaska, British Columbia, Washington, and California. Recolonizations have been reported in Mexico and Japan. Population estimates made between 2004 and 2007 indicate a global population of nearly 107.000 individuals.
Russia
Currently, the most secure and stable area of their range is Russia. Prior to the 20.000th century, there were around 25.000 to 750 sea otters in the Kuril Islands, located mostly in Kamchatka and the Commander Islands. After years of intense hunting, the population dwindled to only XNUMX individuals.
Since 2004, sea otters have repopulated their traditional habitats in the area, with an estimated population of 27.000. Of these, approximately 19.000 are found in the Kuril Islands, 2.000 to 3.500 in Kamchatka, and 5.000 to 5.500 in the Commander Islands. This trend has slowed slightly, suggesting that the population is reaching its limit.
British Columbia and Washington
Along the southern coast of Alaska, the species' distribution is not continuous. From 1969 to 1972, eighty-nine individuals were transferred from Alaska to the west coast of Vancouver Island, British Columbia. These resulted in a healthy population, estimated at over 3.000 animals in 2004, with a range extending from Tofino, Canada, to Cape Scott Provincial Park. A self-contained colony was found on the coast of central British Columbia in 1989.
It is unknown whether this colony, which consists of about 300 individuals, originated from transferred otters or are survivors of the fur trade. From 1969 to 1970, fifty-nine sea otters were transferred from Amchitka Island to Washington. Annual monitoring conducted from 2000 to 2004 revealed between 504 and 743 individuals, and their range extends from the Olympic Peninsula just south of Destruction Island to Pillar Point.
California
Thanks to a survey conducted in the spring of 2007, they were able to count 3.026 sea otters along California's central coast, a number lower than the pre-hunting season estimate of about 16.000 animals. These animals are descended from a surviving southern sea otter colony of about 1938 animals found near Big Sur in XNUMX. This colony is primarily distributed from south of San Francisco to Santa Barbara County.
In the late 1980s, the U.S. Fish and Wildlife Service relocated about 140 California iguanas to San Nicolas Island south of the peninsula, hoping to establish a reserve population unaffected by a potential oil spill. To the astonishment of biologists, the San Nicolas population declined sharply as many animals returned to the mainland.
When the Fish and Wildlife Service implemented the relocation program, it also sought to lessen the rivalry between otters and fishing vessels by establishing an otter-free area between Point Conception and the Mexican border. Within this area, only San Nicolas Island was designated as a sea otter habitat, and any individuals remaining in the area were to be trapped and relocated. The project was abandoned when it was determined that trapping hundreds of otters that would then return to the area was impractical.
However, after the issue was publicly addressed in 2005, the Fish and Wildlife Service has not formally resolved the matter. Sea otters were once abundant in San Francisco Bay. Data collected shows that the Russian-American company imported Aleuts into the bay on several occasions, despite the Spanish trapping or shooting them while hunting sea otters in the San Jose, San Mateo, and San Bruno deltas, and near Angel Island.
Ivan Kuskov, who founded Fort Ross, caught few otters on his second trip to Bodega Bay in 1812, but he sent a group of Aleut fishermen to San Francisco Bay, where, along with Russian and American teams, they caught 1.160 otters over a three-month period. By 1817, the sea otters in the area were nearly exterminated, and the Russians requested permission from the Spanish to hunt south of San Francisco.
Residual populations of sea otters may have survived in the bay until 1840, when Rancho Punta de Quentin was awarded to Captain John B.R. Cooper by California Governor Juan Bautista Alvarado, who was also granted a sea otter hunting license. Although the southern sea otter's range has steadily expanded from Big Sur since it was granted protection in 1911, the otter population and range have declined in recent years.
Recently, a toxin called microcystin, produced by a type of cyanobacteria (Microcystis), appears to be concentrating in marine animals that feed on otters, causing poisoning. Cyanobacteria are found in stagnant freshwater enriched with nitrogen and phosphorus from septic tanks and agricultural fertilizer runoff, which can be carried into the ocean by currents during the rainy season. In 2010, a record number of sea otter carcasses were found off the California coast, and shark attacks were cited as the cause of the increased mortality.
Oregon
The last natural sea otter in the state of Oregon, United States, was hunted in 1906. From 1970 to 1971, a total of ninety-five individuals were reintroduced from Amchitka Island, Alaska, to southern Alaska. the Oregon coast. However, this endeavor was a failure. In recent times, in 2004 and 2009, solitary males could be observed on the Oregon coast, supposedly from the populations of Washington or California.
Key Species
The sea otter is a typical example of an essential species; their existence impacts ecosystems more significantly than their size and quantity might suggest. It can regulate the population of certain herbivores on the ocean floor, such as sea urchins. These subsist based on the lower section of the algae stems, causing them to break off and die. As the habitat and nutrients provided by kelp forests are lost, there is a profound cascading impact on marine ecosystems.
Regions of the North Pacific lacking sea otters often become barren seabeds, with abundant sea urchins and the corresponding loss of kelp forests. The reintroduction of sea otters in British Columbia has led to a significant improvement in the vitality of the coastal ecosystem, with similar changes observed as otter populations recovered in the Aleutians, the Commander Islands, and off the coast of California.
However, certain California kelp forest ecosystems have also improved without the influence of sea otters, with sea urchin populations seemingly stable due to other circumstances. The role of this species as a kelp forest benefactor is more evident on unobstructed coasts than in bays and deltas. In addition to fostering kelp forest growth, sea otters can have a profound impact on rocky areas that tend to be covered by layers of mussels. They strip the mussels from the rocks, making room for other species, creating diversity in the area.
predators
Orcas and sea lions are the most well-known predators of this animal species. Bald eagles capture young that swim above the water's surface. Shark attacks, primarily great white sharks, have been blamed for 10% of sea otter deaths in California and are considered one of the reasons why their population has not expanded further north. Individuals have been found killed by sharks, however, there is no evidence that they are a food source for them.
Relationship with Humans
As part of their connection with humans, this species has historically been exploited for its fur, an activity that nearly led to its extinction, a process that has been contained thanks to conservation initiatives. On the other hand, conflicts have arisen over the acquisition of marine species consumed by sea otters, which are also an important part of fishing activity in the creatures' distribution areas.
Leather Trade
Archaeological findings indicate that for thousands of years, native people have trapped these creatures for their meat and fur. Large-scale hunting began with the fur trade, which is responsible for the deaths of nearly a million individuals. This began in the 18th century when hunters and traders from around the world began arriving to supply the global demand for sea otter fur, which had become one of the most valuable in the entire market. At the beginning of the century, the Russians began hunting them in the Kuril Islands to trade their fur in China.
The Russians were also exploring the North Pacific at the same time and sent Vitus Bering to map the Arctic coastline and, in doing so, locate new routes from Siberia to North America. In 1741, on his second voyage through the area, Bering's ship foundered off Bering Island in the Commander Islands, where he and many of his crew perished.
The survivors, including the naturalist Georg Steller, managed to discover sea otters in the island's bays and spent the winter trapping sea otters and gambling on their fur. They returned to Siberia after killing nearly a thousand otters, earning high prices for their fur. This marked the beginning of an intensive hunting season, which continued for a decade.
Russian fur excursions rapidly reduced the population of the species in the Commander Islands, so that in 1745 they began to move throughout the Aleutian Islands. The Russians initially traded with the natives of these islands for fur, but soon subdued them, confining their women and children as prisoners, torturing and murdering them to force them to hunt otters.
Numerous Aleuts perished either at the hands of the Russians or from diseases brought by them. According to figures provided by the Russians, the Aleut population decreased from 1760 to 1799. By the XNUMXs, the Russians had reached Alaska. In XNUMX, Emperor Paul I merged the competing hunting companies into a single Russian-American corporation, granting it imperial privilege, defense, and exclusive rights to trade and territorial purchases.
Under Alexander I, management of the company was transferred to the Imperial Navy, primarily due to alarming reports from naval officers about abuses against the natives. By 1818, Alaskans were guaranteed civil rights similar to those of citizens of the Russian Empire. In addition to Russia, other countries collaborated in the sea otter hunt in the southern part of its territory.
Along the California coast, Spanish expeditionaries acquired sea otter fur from Native Americans to trade in Asia. In 1778, the English explorer James Cook landed on Vancouver Island and was able to purchase otter fur from Indigenous Canadians. When Cook's ship stopped in a Chinese port, the fur sold quickly and for a high price. As word spread, people from all over Europe and North America began to flock to the Pacific Northwest to join the fur trade.
The Russian hunt extended southward, sponsored by American ship captains, who subcontracted crews of Russian foremen and Aleut hunters to work in present-day Washington, Oregon, and California. From 1803 to 1846, seventy-two American-origin vessels participated in the otter hunt in California alone, netting an estimated forty thousand pelts, compared to just thirteen vessels belonging to the Russian-American Society, which reported only 5.696 otter pelts collected from 1806 to 1846.
There came a time when the numbers of this mammal became so scarce that commercial hunting was no longer profitable. In the Aleutian Islands, hunting was banned in 1808 due to a conservation law demanded by the Russian-American Society. In 1834, additional restrictions were established by the same society. When Alaska was sold to the United States by Russia in 1867, the population in this region had already increased by more than XNUMX individuals, but the Americans resumed hunting and once again wiped out the population.
As soon as the species became exotic, prices increased: in the 1880s, the price of a single skin was US$105 to US$165 on the London market, but by 1903, the price had soared to US$1.125. By 1911, Russia, Japan, Great Britain (through Canada), and the United States, as members of the Treaty for the Preservation and Protection of Fur Seals, imposed a moratorium on sea otter hunting. By that time, the world population had probably declined to only XNUMX or XNUMX.
Recovery and Conservation
Throughout the 20th century, the sea otter population recovered to nearly two-thirds of its original population, considered one of the most significant achievements in marine conservation. However, the International Union for Conservation of Nature (IUCN) still lists the species as threatened due to significant threats such as oil spills, predation by killer whales, illegal hunting, and conflicts with fishermen (otters can drown if entangled in fishing gear).
Hunting of the species is illegal except for subsistence hunting by Native Americans in Alaska. Illegal hunting became a serious threat in Eastern Russia after the dissolution of the Soviet Union in 1991. However, it declined significantly as stricter regulations were implemented and the country's economic situation improved. Currently, the most significant threat to sea otters is oil spills.
Sea otters are particularly vulnerable to contact with oil, as they rely on the waterproofness of their fur to retain heat. When their fur is soaked with oil, it loses its ability to retain air, and the creature quickly dies of hypothermia. The otter's liver, kidneys, and lungs are also damaged after inhaling or ingesting oil while grooming their oil-soaked fur.
The 1989 Exxon Valdez oil tanker accident killed thousands of sea otters in Prince William Sound, Alaska, and oil spills in the area were still damaging the population as recently as 2006. The restricted range of this species' populations in California, Washington, and British Columbia means that a large oil spill could be a disaster for the animals in these areas. The most important goals of conservation efforts are spill prevention and preparedness to rescue otters should one occur.
Increasing the size and range of otter populations could help reduce the risk of a spill depleting a population. However, because of the species' reputation for depleting fisheries, those promoting commercial, recreational, or subsistence harvesting of shellfish have often opposed increasing their range, and there have been cases of illegal killings at the hands of fishermen and others.
In the Aleutian Islands, a massive and sudden decline in the sea otter population has occurred in recent decades. In the 1980s, the area supported an estimated 55.000 to 100.000 individuals, but the population had declined to just 6.000 by 2000. The most widely accepted, though still debated, theory attributes this to killer whales. The pattern of extinction is consistent with increased predation by killer whales; however, there is no direct evidence that killer whales eat otters in significant numbers.
Another area of concern is California, where recovery began to fluctuate or decline in the late 1990s. Extremely high mortality rates have been reported among adult and sub-adult otters, especially females. Necropsies indicate that infections, primarily caused by parasites such as Toxoplasma gondii and acanthocephalans, account for the majority of deaths in this area. Toxoplasma gondii, which is often fatal to sea otters, is carried by wild and domestic cats and opossums, and can be transmitted to cats through feces dumped into the ocean via sewage disposal.
Although it is known with certainty that parasitic infections have caused the deaths of a large proportion of California sea otters, it is unknown whether this specific population is more affected by these diseases than populations in other areas. The sea otter's habitat is protected by several protected areas in the United States, Russia, and Canada.
In these regions, polluting activities, such as the dumping of oil-related waste, are prohibited. There are an estimated 1.200 specimens in the Monterey Bay National Marine Sanctuary and more than XNUMX in the Olympic Coast National Marine Sanctuary.
Economic impact
Some sea otters feed on other species that are food sources for humans, such as abalones, clams, and crabs. In other areas, sea otters have been blamed for the significant decline in shellfish harvests, and there has been heated public debate about how to manage the rivalry between otters and humans over marine resources.
The controversy is complicated by the fact that the species has been blamed for the decline of shellfish stocks, a situation most likely caused by other factors such as human overfishing, disease, pollution, and seismic activity. The decline in shellfish harvesting has also occurred in many areas along the North Pacific coast not populated by sea otters, and conservationists have also noted that the presence of large concentrations of shellfish along the coastlines was a recent outbreak resulting from the near-decimation of sea otter populations.
Since numerous factors impact shellfish stocks, predation by sea otters can render fishing unprofitable. There is a consensus among researchers that sea otters and abalone fisheries cannot coexist in the same area. This probably applies equally to other animals. There are numerous factors in the interaction between sea otters and the human economy that are not immediately apparent.
These have helped increase seaweed harvests due to the regulation of sea urchin populations. These algae are used in the production of various food and pharmaceutical products. Although divers are able to collect red sea urchins for food and to provide protection for the seaweed, sea otters, coupled with the fact that they hunt other species, are more effective in regulating these populations.
A healthy kelp ecosystem is important for sustaining fish populations, including those of commercial importance. In certain areas, sea otters are a popular tourist attraction, attracting visitors to local hotels, restaurants, and excursions to watch them.
Captivity
Sea otter pups have been placed in captivity for display in at least 1979 aquariums and zoos. The Seattle Aquarium became the first facility to house pups with the arrival of Tichuk in 1980, followed by three more pups in the early 2007s. By 1,5, a YouTube video of two otters holding paws had garnered XNUMX million views in a couple of weeks and now has XNUMX million views. It was filmed five years ago at the Vancouver Aquarium and was the most popular animal video at the time.
The lightest-colored otter is named Nyac, who survived the Exxon Valdez disaster. Nyac died in September 2008 at the age of 20. Since the mid-1970s, the species has become popular among nature lovers and scientists. Today, it has become an important symbol of environmental conservation. The sea otter's round, articulate face and smooth, furry body have been depicted on a wide variety of souvenirs, postcards, clothing, and stuffed animals.
Other Types of Otters
Otters make up a group of 12 species (where the sea otter must be added) in 8 genera, and we can consider them as quite successful evolutionarily creatures, since they have reached all continents except Oceania.
Giant Otter (Pteronura brasiliensis).
It is one of the largest mustelids, or at least the longest of all, reaching almost 2 meters in length (1,7–1,8 m) and a typical weight for males of about 32 kilograms. It resides in the Orinoco and Amazon river basins in South America, where it feeds on fish but also crustaceans, turtles, and even small caimans. Except for humans, who have hunted it for its fur, it has no natural predators, which is why this otter is considered one of South America's apex predators.
From a taxonomic perspective, it is a somewhat separate otter from other living otters, as its lineage was the first to diverge from the common stock. Its ancestors arrived in South America during the Great American Interchange, but it developed independently of the other Neotropical otters of the genus Lontra. Two subspecies are known.
North American River Otter (Lontra canadensis)
At first it was cataloged under the genus Lutra, and later it was assigned the genus of all American otters except the giant otter, that is, Lontra. It resides in North America, essentially from Alaska to Newfoundland (excluding the polar regions), and descends as far east as the Mississippi estuary and as far west as California. It is not present throughout the Central United States and in desert regions. Seven subspecies are known to him.
Huillín or River Cat (L. provocax).
This otter is located in the southernmost part of South America: the Patagonia of Chile and Argentina. Although it has the ability to reside in both fluvial and marine environments, it is mostly inclined towards rivers and lakes with a large presence of vegetation.
Neotropical Otter (L. longicaudis)
In its appearance it is very similar to both the North American otter and the river cat, but it is located precisely in the intermediate zone between this other pair of species. More specifically, it resides in tropical fluvial environments from Mexico to Northern Argentina, and also inhabits the Island of Trinidad, and is the species of its genus with the widest distribution. It is the otter with more general habits and prefers faster and more crystalline waters, thus avoiding competition with the giant otter, which is more prone to low and calm waters. Six subspecies are recognized.
Chungungo or South American Sea Otter (L. felina)
It is, together with the northern sea otter, the only one with exclusively marine customs. It is very rarely seen in deltas or rivers, and lives throughout the Pacific coast of South America from Peru to Tierra del Fuego. It is one of the smallest otters (it weighs a maximum of 5 kilograms) and is the most modest sea mammal.
Clawless Otter (Aonyx capensis)
It is the second largest river otter species, and it is found in river areas of sub-Saharan Africa, in savannah and lowland dry forest areas. Six subspecies are recognized.
Spotted-necked Otter (Hydrictis maculicollis)
In sub-Saharan Africa it can be found almost precisely in those spaces where the clawless otter is not found: the aquatic environments of the tropical and equatorial forest region of Central Africa.
Palearctic Otter (Lutra lutra)
It is the species of the Old World with the greatest distribution: almost the entire Eurasian continent from the Iberian Peninsula and Ireland to the Pacific Ocean (except for the polar areas and the most desert areas), and as far south as North Africa, and it even goes into Indo-Malay in certain parts of India and Indochina. Some authors estimate that the Japanese subspecies L. l. nippon was a separate variety. This otter was annihilated by humans around the 80s of the XNUMXth century, due to the fur trade.
Sumatran Otter (Lutra sumatrana)
It is the most exotic and ignored of all otters. From a historical point of view it was found in southern Indochina to Borneo and Sumatra, but was hunted to extinction. Since 1998 recent populations of this species have been rediscovered in Thailand, Vietnam, Indonesia and Cambodia and Myanmar. It is listed as "Endangered".
Smooth Otter (Lutrogale perspicillata)
It is the otter with the largest distribution area in the Indo-Malaysian Region, being found in almost all of India and Indochina, including Sumatra and parts of Java. There is even a remnant population in southern Iraq, which forms an exclusive subspecies, together with two other recognized ones.
Small Clawless Otter (Amblonyx cinerea)
It is the smallest otter, weighing from 1 to 5 kilograms. There are controversies about its taxonomy, alternating the possibilities between the genera Amblonyx, Aonyx and Lutrogale. It lives in mangrove swamps and freshwater lowlands in Indochina, Borneo, Sumatra, Java, and also in certain areas of India. It leans towards calm and intertidal waters, as well as rice crops.
Otters Soaked in Oil
In just a few hours, the ship 'Exxon Valdez' spilled some 41.000 cubic meters of oil on the coast of the town of Prince William Sound, Alaska: an amount that would fill 16 Olympic swimming pools and stain up to 2.100 kilometers of coastline. Among other circumstances due to the storm that swept the delta three days after the spill and that expanded the stain beyond that region.
The giant oil industry Exxon had to spend some 2.000 million dollars on cleanup tasks and put into action a hundred aircraft, a thousand ships and some 13.000 employees who had to resort to different methods to suppress the traces of the spill in the sands of the estuary beaches. Neither the government employees nor the company managers knew how to remove the oil from the rocks. They tried chemical solvents, pressurized water, and hundreds of kilometers of absorbing beacons.
But they were only able to recover 7% of the oil and did not prevent the spill from causing irreparable damage to the area's ecosystem. No one knows exactly how many animals lost their lives in the spring of 1989. Authorities say 250.000 seabirds, 22 killer whales, 247 bald eagles, some 300 seals, 2.800 sea otters, and millions of herring and of salmon. Certain animals died from ingesting the spilled oil. In others, the oil rendered them sterile, perforated their livers, or adhered to their skin, causing fatal hypothermia.
There is no one who has known better the challenges of those times than Kelley Weaverling, who coordinated the operation to recover the animals of the delta after the 'Exxon Valdez' spill. "The company hadn't taken the animals into account and no one knew what to do," she recalls in a cold voice. «Anyone who had an idea was left in charge and I was selected because I knew the delta well. He had crossed it numerous times by canoe and had made notes about the beaches and the fauna of the site».
Kelley is a thin man with metal glasses and a Gandhi-shaven haircut. He and his wife arrived in Cordova in 1987, enchanted by the town's sustainable economy, and have since run the Orca Bookstore: a store that sells postcards, provides free Internet, and offers the best coffee in town. "At that time a salmon was worth more than a barrel of oil," Kelley notes wryly. "We considered that if we moved here we would not be affected by the ups and downs of the oil industry and see what an irony: two years later we had to suffer the 'Exxon Valdez' spill."
The incident did not surprise us here in Cordova, whose fishermen had been able to contain the construction of the Valdez oil pier for a time with an indictment. Leaders such as the Republican Governor Jay Hammond (1974-1982) then supported the layout of a pipeline that would transport crude oil by land through Canada. But the industry was inclined to build the maritime dock from which the 'Exxon Valdez' crude oil came out.
"At that time it was not allowed to export crude oil from the Arctic to other nations," explains Kelley, who served as mayor for several years. “But I suspect that the companies saw the oil tankers as a future bet for the moment when the government lifted that ban. We cannot forget that Alaska was closer than any other place in the United States to export to nations such as Japan or South Korea.
The days immediately after the spill were crazy. At that time there were no cell phones or the Internet. In Cordova there were only two fax machines and the fishermen's phones rang all the time. If you tried to phone Valdez, the lines were always busy and it was hard to know what to do.
"The Coast Guard announced that the airspace had been closed," says Kelley. “But some pilots flew their aircraft to where the ship was and we marked on a map how far the oil slick reached. Nobody knew what was happening. There were hundreds of ships here ready to go but Exxon told us to stay put. It would have been better to start the day before and collect the oil with plastic buckets. But we waited for three days until the storm came and by that time there was nothing to do.
The oil from the 'Exxon Valdez' spread to far away places on the Alaskan coast. If the ship had capsized off the southern tip of Florida, the oil would have covered the US coastline up to the Canadian border.
Exxon officials then blamed the magnitude of the disaster on the government's refusal to disperse the crude with solvents. However, Kelley points out that this is not true: «With solvents, the oil does not vanish. It remains at the bottom of the sea and kills the microorganisms that live in the delta. The plankton are not as charming as the sea otters but they are of great value to the ecosystem in this area.”
Chaos also reigned during the animal rescue. Kelley recalls that Exxon had limited itself to calling in two non-governmental organizations whose managers were specialists in birds and marine mammals, but they were unfamiliar with the environment in which they would be working. "There was no plan to rescue the animals, nor were there any vessels assigned for the task," he recalls angrily. "There was no equipment or trained personnel for the task. There was also no defined chain of command or plan to transfer the animals to a recovery center."
Seven days after the spill, authorities had to turn to Kelley, who proposed some ideas and began working with a group of local people. "We did some very obvious things that no one had thought of," he recalls, reviewing the report he wrote a few months after the spill. "It was quite complicated to rescue the otters because they are very elusive creatures, and it was a particularly trying experience for me since I had slept on many of those beaches. It's not that I knew the species. It's that I knew about that seal, that orca, or that walrus. I took this rescue operation very seriously."
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