The sea otter ( Enhydra lutris , Linnaeus 1758), is large a Loutre (family of the Mustélidé S) alive in the Northern Pacific, of the north of the Japan (island of Hokkaidō) to the California, while passing by the Kamtchatka, the Aleutian Islands and the Alaska. It is most watery and most massive of the otters, the only one with being able to live permanently in the sea.

The sea otter should not be confused with the “marine otter”, Lontra felina , still called cat of sea or chungungo, which lives along the coasts of the Peru and the Chile and which needs terrestrial shelters. It arrives as sometimes as certain fresh water otters, like the Loutre of Europe, make incursions at sea (the case is even rather frequent in certain countries as in Ireland), but their organization is not adapted to prolonged stays. The sea otters form the only species of the kind Enhydra .

Driven out intensively as from 1741 for their fur (densest of all the mammals with until 170  000 hairs per square centimeter), the populations of sea otter were considerably reduced, disappearing even from many areas of their zone of historical distribution. In 1911 one estimated that their world population had fallen between 1  000 and 2  000 individuals. Although several subspecies are still in danger, the marine otters, which are legally protected, saw their population strongly increasing. The efforts of reintroduction also showed positive tests.

Physical description

The sea otters are heaviest of the otters, but not largest.

With their long profiled bodies, the sea otters are adapted to the life at sea, a moderate sea (California) with cold (Alaska, Kamtchatka) whose temperature often oscillates between 1 and 10° only. The otter had to develop very particular adaptations to survive in such a medium, in particular on the level of its fur.

This one varies from brown reddish with the black. Particularly dense (140  000 with 170  000 hairs per square centimeter), it insulates the animal and maintains a layer of air under the hairs, creating an effective barrier between water and the skin. Peeling comprises long hairs, brilliant, thick and resistant: earthenware jars. It comprises also short hairs, very dense, finer: flock. The otter coats its hairs with the oily cutaneous gland secretion, which waterproofs them temporarily, and must regularly be réappliquée. Time spent to waterproof its fur by the sea otter is several hours by jour.
The waterproofed hair (especially flock), retains many bubbles of air which ensure the thermo isolation (the skin remains more or less dry). In the young people, the quantity of air is such as those can neither plunge nor to run, which is essential in measurement or they cannot swim with the birth.

The otters do not have a layer of insulating grease like the others Marine mammals. Water causing a loss of heat 25 times faster than the air, the warm-blooded animal which live in water must isolate, but also produce more heat. The insulation is provided in the sea otter by the fur, the production of heat by a Métabolisme approximately twice higher than at a Mammifère of the same size. This metabolism explains why the sea otter must eat nearly 25% of its weight each day to maintain its temperature internal of 35° Celsius (10% only at the Loutre of Europe, which spends much less time in water). Other adaptations to the aquatic life:

• the nostrils and the ears are closed hermetically during the diving;
• the thorny apophysis (“spines” which leaves the spinal column) is very developed, as at others Marine mammals, which offers a better anchoring to the muscles of the back;
• blood circulation with the characteristic (known as Rete mirabile ) to be made up (under the Derme) by a mixture of small Veine S and small Artère S, veins being structured to profit from the heat released by the arteries, which reduces the losses of heat;
• the lungs are 2,5 times broader than those of an of the same mammal cuts, to support the divings (the otter does not have indeed the thick layers of grease of the other marine mammals, which are useful to them with the thermo isolation, but also to store oxygen for the divings);
• the rate of Hémoglobine is more important than in a terrestrial mammal, facilitating the storage of oxygen in diving;
• the blood of the sea otters has a great regulating capacity which helps these animals to support excesses of CO₂ accumulated under the pressure during the diving;
• the births can be deferred in the event of too disturbed marine climate ( to see the chapter reproduction );
• the upper lip, the nose and the top of the eyes are surrounded by long Vibrisse S (resembling the “moustache” of the cats) which locate the movements of water, which makes it possible the animal to move and drive out in aquatic environments with low visibility;
• the eyes, the ears and the nostrils are located on the top of cranium, as at much of aquatic animals with air breathing, which makes it possible the otter to remain dissimulated in water while breathing and by supervising the neighborhoods;
• the front legs have retractile claws, whereas legs - posterior fins longer, are largely flattened and webbed: these are especially the last which are used for the propulsion.

Under each powerful leg before a pocket of skin, employed is to temporarily store the food collected during the divings at the bottom, or the stones which they readily use as tools.

The otters have a rather short, thick and musculeuse tail, which is used to them as rudder.

The male otters can reach a maximum weight of 45 kilograms and a length going up to 1,5 meter. The average is however rather of about thirty kilograms for the males. The females are smaller (a little more than 1 m), with sometimes only 70 cm, for an average weight of approximately 23 kg.

The females only have two Mamelle S.

The otters carry out relatively long lives: up to 23 years in nature (fifteen - twenty years on average).

Behavior and reproduction

The sea otters can be solitary or live in groups. These animals are in general rather social, and one belonged in Alaska to the groups cash until 2  000 individuals. In California, where the population is less important, the groups make rather from 10 to 100 individuals. The groups are often sexually separate, the groups of males being in general more important than those of the females.

On the surface, the sea otters often swim on the back. One can suppose that it is about one adaptation to the cool water life. This position makes it possible to maintain the end of the muzzle and the legs out of water. These zones of the body are indeed deprived of fur (but only 1% of body surface represent). The otters pass in ventral posture when they wish to swim more quickly, for example in situation of escape. They rest on the back while being rolled up in the giant slings of the Kelp, which avoids to them deriving while they eat or during their sleep.

Forests of kelp

The forests of Kelp are true forests of Algue S giants, being able to make several tens of meters length. These algae are anchored on the ground and float to surface thanks to the floats which are at the base of the sheets. These forests are a habitat privileged for the sea otters thanks to the anchoring which they provide (the otters wrap themselves in the sheets floating on the surface) protecting them from the storms and the currents and thanks to abundance from the food which is there. However, the sea otters are not strictly pledged with the forests of kelp, and certain groups live in zones without kelp.

It was noted that the sea otter had a favorable impact on the extension of the forests of kelp: the otters enormously eat sea urchin S, which are brouteurs of kelp. Where the otters return, the kelp goes better and its forests develop, making it possible all kinds of animals (invertebrate but also fish) to develop to with it. Where the otters are absent, the forests of kelp are degraded and more restricted.

This action on the kelp can play besides in favor of the otters. The Californian fishermen of ormeaux indeed a long time regarded the otters as competitors, because the otters are predatory the ormeaux ones. Although prohibited, the shootings of the otters by these fishermen are thus not rare. But the ormeaux ones depend on the forests of Kelp or they live, forests which the otters contribute to extend. The otters thus have a long-term positive impact on the populations the ormeaux one. Some hope that the discovery of this positive impact will contribute to slacken the atmosphere between Californian fishermen and otters.

Displacements and search for food

The sea otter comes to ground where that is possible, especially to protect itself from the storms, but really need does not have any, not even for the reproduction, which is largely watery, of the design to the birth (see the chapter reproduction). Close to the very inhabited zones (as in California), certain populations of otters come never or almost never to ground.

The contradictory data concerning displacements of the sea otters suggest that those (or their absence) depend on the availability of the food resources. They move generally only from 1 to 2 km per day, and have territories which can exceed 5 km ².

The sea otter is an animal Diurne. The major part of its day is devoted to grooming and research of food.

Grooming is essential: deprived of insulating grease, the sea otter depends for its survival on the protection offered by its fur. This one must be regularly cleaned and lubricated (see the physical chapter description ) to preserve its effectiveness, under penalty of Hypothermie.

The search for food is more intense the morning and the evening (twilight food).

The otter takes its preys on the sea-bed. The divings are rather short, generally not lasting more than 90 seconds, but they can reach 4 or 5 minutes. Food largely consists of shells and sea urchins, but also of crabs and fish.

Because of this food, which lives primarily on the bottom, the sea otter lives only in zones where the depth of the ocean does not exceed a few tens of meters, very close to the coasts. The record of diving recorded is of 97 meters. But the usual divings are limited to 20 or 30 meters. The consumed quantities of food each day are important, reaching approximately 25% of the weight of the animal (either ten kilos for a large adult). They make it possible to maintain a temperature of 35° in cool water (1 with 10° Celsius).

Floating on the back, the otters wash and (with the need) their preys with a rock open which they keep in their pocket. The rock perhaps used as anvil: the animal makes the board, poses the stone on its belly, and strikes the shell above. It can also be used as hammer. The sea otters thus present a rare example of a use of Outil by a nonhuman mammal ^, .

Reproduction

Really a season ago of reproduction, but one notes points between May and June in the Scandinavian populations, and between January and March in the southernmost populations.

The males have multiple female partners, but without common life. The males and the females approach during heats the female. The females avoid males apart from this period. During the period of heats, the males defend their territories; there are very seldom real combat, the majority of the conflicts being regulated by intimidation. The adult females have scars characteristic of the practice which have the males to hold to them the head between their jaws during the reproduction.
When the males and the females are made the court, they swim quickly and plunge together, the making male of the corkscrews in water. During the coupling, the male bites the female on the nape of the neck, the neck or the nose, leaving him scars.

The Gestation is from 4 to 6 months, although it can be prolonged several days at one year if the fertilized egg is not immediately inserted in the uterine wall . For this period of suspension, the egg does not develop. This occurs in particular when the agitation of the sea (storms) disturbs the establishment. It is undoubtedly about an adaptation which optimizes the reproduction and the protection of the young people in the hard medium of a cold ocean to the frequent storms.

The Gestation usually finishes by a simple birth. The twins are a scarcity, and usually only one of them survives. The new-born babies make 1,5 to 2,3 kg, have the open eyes and an already thick fur, to float and survive in cool water. The large size of small is very with fact unusual at a Mustélidé. According to James Bodkin and Daniel Monson, of Alaska Science Center, this size important is an adaptation to the rigors of the oceanic life. They note on this subject that the relationship between the weight of the mother and that of small the Enhydra lutris is much closer to that existing at the Pinnipède S than at the Mustélidé S in general.

The births can be done with ground with fast transport of young people towards water, or directly at sea. The number of the births at sea would be more important in the otters of California (even if one finds there births terrestrial according to R.J. Jameson) that at the 2 Scandinavian subspecies.

In the event of death of small, the female often enters in heat the days which follow, and falls down pregnant almost at once. The deaths of small being more frequent the winter, taking into account the climatic conditions, this characteristic ensure a birth one moment statistically more favorable, i.e. spring or the summer.

The small ones can assimilate solid food very little time after their birth. They are yellow brownish, and remain permanently close to the mother, on which they are dependant six months or more. The mother teaches with small how to drive out, plunge, and toiletter effectively. She is in general small every years or every two years old. Those start to plunge towards the 2 months age. They remain with mother 5 to 8 months after the birth.

The males reach sexual maturity towards 5-6 years. The majority of the females are sexually mature towards three or four years, sometimes even 2 years: “A small proportion of the females has its first small at 2 years, approximately 50% reproduce for the first time at the 3 years age, and the majority of the females had small at the 4 years age”.

Destruction of the otter

The habitat of the sea otter went at the origin of the north of the Japan (Hokkaidō) to the north of the Mexico (Péninsule of Low-California), while following the north-Asian dimension, the Aleutian Islands then the peaceful dimension of North America.

The population undoubtedly counted hundreds of thousands of individuals (a million, according to certain estimates). The number of the subspecies is difficult to determine, but there are three of them today. Have regard to the importance of the destruction of the populations, it is possible that certain subspecies disappeared before to be described.

With XVIIe and XVIIIe centuries, the Russia was strongly implied in the trade of the fur of Zibeline. The Tsar Pierre Large the wished to develop this economic activity, and to find new populations to be driven out. The Russian hunters settled more and more far in Siberia, until the Kamtchatka, peninsula rich in sable, but where one found also sea otters. In 1741 and 1742, Vitus Bering and Alexei I. Chirikov were charged by the Russian government exploring the northern Pacifique and with tracing a sea route towards the America starting from the new Russian possessions of the Far East. During their wintering 1741-1742, the crews collected skins of otter. In 1742, the survivors of forwarding (Bering had died) returned to Russia with 900 skins of otters, which interested the merchants of fur highly. Let us recall that with close to 170  000 hairs per cm ², the fur of sea otter is particularly dense and silky. It was the beginning of the great hunting.

The Russians sent many boats to drive out the fur of otter. After the exhaustion of the north-Asian populations of otters, the catch of the Aleutian Islands then of the Alaska by Russia was largely justified by the will to extend the territories of hunting to the otter, become a particularly profitable activity.

In 1784, the Russians established counters of draft on the Aleutian Islands and the coast of America, in Alaska. Coastal stations were built with Attu, Agattu and Unalaska, in the Aleutian Islands, like the island of Kodiak, with broad of the mouth of the handle Cook (Alaska). Eighteen months later, a colony was established on the continent, opposite the Cook handle.

The indigenous populations were often savagely treated. Aléoute S were reduced in slavery, and others would have been taken as hostages to force the indigenous population to drive out the otter on behalf of the Russian merchants. Approximately 25  was counted; 000 Aléoutes before the arrival of the Russians, they were nothing any more but 3  892 in 1885.

The fur of otter was sold not only in Europe, but also at ransom price on the Chinese markets.

In 1776, the captain James Cook explored the northern Pacific on behalf of the Great Britain. It is during this forwarding that the fur of otter was identified by the British like a trade at strong potential, attracting as of the end of the 18th century of new hunters in the area, in particular American Britanniques, Spaniards then.

The Alaska almost completely having been emptied of its populations of sea otters became not very interesting for the Russian government, leading this one to sell this territory (and the Aleutian Islands) with the the United States in 1867.

Towards the end of the 19th century, hunting ceased being profitable. The populations of otter had almost completely disappeared. The last known otter of the American state of the Oregon was thus killed in 1906. Forwardings of hunting could not bring back skins enough any more to be financed.

Certain biologists think that about 1911, there remained nothing any more but 1  000 with 2  000 live animals.

Protection

The pressure of the merchants of fur having disappeared with the commercial interest from hunting, the sea otter was protected in 1911 by the International treaty on the Seal with fur , having ratified by the United States, Russia, Japan and Great Britain, at one moment when much thought that she was already condemned.

Survivors

Although the hunting of otter was officially prohibited, and that the animals became very difficult to find, of the poachers continued to drive out them. The Japanese poachers were thus about to completely eliminate the remaining otters in the Aleutian Islands (American possession since 1867) during the release of the Second world war. The zone was militarized by the two parts. There was an occupation partial of the islands by the Japan and the reinforcement of the American military presence in the remainder of the zone. Because of this militarization and dangers related to the state of war, the poaching ceased.

With the group of Aleutian Islands, other small populations survived of accuracy, in particular in Alaska or with the Kamtchatka. A group was identified with broad of Carmel, in California in 1938, in a zone where it was thought that the otters had completely disappeared. An estimate of 1976 considers that there was to be about fifty survivors of E. lutris nereis about 1914. Other estimates only speak about 10 to 30 survivors.

These various survivors allowed the 3 subspecies to naturally reconstitute themselves, colonizing the zones gradually being around them.

An example of recolonisation, that of Enhydra lutris nereis , the Californian subspecies:

Reintroductions

In addition to the natural growth of the populations, crowned reintroductions of success were carried out along the North-American coasts to accelerate the recolonisation, in particular in the South-east of the Alaska, in the State of Washington (the USA) and in Colombia-British (Canada).

For example, 89 sea otters of Alaska were introduced in several stages as a Colombia-British in 1969 and 1972. This small population quickly increased, since it reached already 1  500 individuals in 1995 (source: Department of the Environment of Canada).

Thus also, 59 otters of Aleutian Islands were established in 1969 and 1970 in water of the State of Washington (the USA). After a rather slow starting (100 animals in 1987), an investigation of 2001 counted 555 of them.

Certain reintroductions, failed on the other hand, or were partial successes. Thus a population of the subspecies Enhydra lutris nereis was installed at the end of the years 1980 around San Nicolas Island, opposite Los Angeles, a little in the south of the zone recolonized naturally by the otter of California. Success was very partial, the population paining to really develop.

There would be in approximately 2006 100  000 with 150  000 sea otters. They were undoubtedly hundreds of thousands before the development of industrial hunting for the 18th century.

The situation of the various subspecies

There are today 3 recognized subspecies (see Wilson on the history of the taxonomy of the species - 1991):

• the sea otter of Asia ( Enhydra lutris lutris or E.L. gracilis , according to classifications) is smallest. She lives on the west coast of the Kamtchatka (federation of Russia) and around the Îles Kouriles. They would be between 15 and 20  000 in 2006.

• the sea otter of Alaska ( Enhydra lutris kenyoni or E.L. lutris , according to classifications), lives on the Aleutian Islands, the coasts of the Alaska. Groups were reintroduced in Colombia-British (Canada) and in the State of Washington (the USA). They would be in 2006 a hundred thousands, especially present in Alaska. The population of Aleutian Islands seems in strong fall, and the center for biological diversity required in 2000 a reinforced statute of protection.

• the sea otter of California ( Enhydra lutris nereis ) is fewer. It has an intermediate size between E.L. gracilis and E.L. lutris . In the beginning, one found it on all the coasts of the south-west of North America. Already rare since 1830, it was completely exterminated at the beginning of the 20th century. Only a few tens of animals survived close to Carmel in California, halfway between Los Angeles (in the south) and San Francisco (in north). Limited to a small zone around Big On (Carmel), the animal gradually developed until almost colonizing all the territory between the two large Californian metropolises ( to see above for a chart of this development ). They would be in 2006 2  800 animals out of 400 km of coast.

It is it should be noted that there exists a problem of name, since certain scientists call the Asian subspecies Enhydra lutris lutris (and not Enhydra lutris gracilis ), and the subspecies aléouto-alaskane Enhydra lutris kenyoni (and not Enhydra lutris lutris ).

The otters are present today in the near total of their old zone of presence, but in a way much less dense, with a habitat in spots of leopard. In practice, only half of water where they lived currently have a presence of otters, and the subspecies of California remains strongly threatened.

Today, the various populations are stable or in regression (according to the zones). One of the advanced assumptions is that of a predation much stronger of the Orque S.

Legal protections

In spite of this relative return, the sea otter is always protected. It is it with the international level (the QUOTE placed the subspecies of California ( E. lutris nereis ) in appendix I: maximum protection, and 2 other subspecies in appendix II), but also by laws of the countries concerned, like the Law on the species in danger and the Law on fishings of the Canada or U.S. Marine Mammal Protection Act of 1972 in the United States.

Predatory and threats

The predatory natural ones of the otter are the Orque S, the Requins, but also certain birds, as the Pygargue (which attacks the young people especially), even exceptionally of predatory terrestrial, as the Coyote (when they come to ground).

The storms and the lack of food can also cause important losses.

Lastly, in certain zones, the pollution and the nets of the fishermen (taken accidental) represent a big risk. It is estimated that the oil slick of the Exxon Valdez, in Alaska in 1989, killed approximately 800 with 5  000 otters (according to the estimates). One also noted a strong mortality in the otters of California because of infectious illness or parasitic supported by pollution.

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