Murie, Olaus J. (1959) FAUNA OF THE ALEUTIAN ISLANDS AND ALASKA PENINSULA, 1936-38, U.S. Dept. Interior, Fish & Wildlife Service, Washington. pg. 279
Sea Otter: Enhydra lutris lutris
Aleut: Attu: Chach-toch
Atka : Ching-d-tho
Morzhovoi Bay (dialect?) : Chngatukh (geoghegan) ; Chgatluk (Wetmore)
Base of Alaska Peninsula: Ahchgh-nahchgh (Osgood)
Kodiak: Ach-an-ah (King)
Kwakiutl Indian: Kas-uh (Dawson)
Russian: Bohr Morskoi (Steller), "sea beaver"
Bobry, adult males
Medviedki, "little bears" — cubs
The northern sea otter is described as being larger than the southern sea otter of the California coast (E. l. nereis). I collected a single specimen at Ogliuga Island on August 4, 1937. It was an old male, weighing 80 pounds, and its measurements, in millimeters, were as follows: Total length, 1,390; length of tail vertebrae, 315; and length of hind foot, 242.
The sea otter is stockier than the land otter, Lutra canadenis, and has acquired other special modifications. Its specialized food habits (discussed later) do not call for great agility, and this may be one reason for the development of a heavier, somewhat less streamlined body than the ancestral form — if we may assume the ancestral form to be similar to that of the present-day Lutra. But the sea otter has become more aquatic than its ancestors, with much less dependence on land, and it has developed seal-like flippers on its hind feet. Its front feet, on the other hand, appear to have responded to a specialized use in handling sea urchins and hard shells of mollusks that make up its principal food. The soles of the front feet have become very thick hard pads, and the toes have more or less coalesced — judging by the specimen examined in detail (mentioned above) the toes are hardly functional as separate digits. The claws have become very weak and pale colored and are placed well up on the dorsal surface of the toes. They probably have little use. The whole structure of the front paw indicates that it is used largely for resisting abrasion from hard sea urchins and shells; it seems incapable of manual dexterity. In fact, the animal seems incapable of holdng anything in one "hand." Yet, I have watched sea otters feeding and have seen them use one paw to toss away, with a forward motion, an unwanted fragment of shell or other substance. Possibly it was only "pushed" away. (Karl W. Kenyon, in correspondence in 1957, writes that a subadult female in the Seattle Zoo is very dexterous. It uses its front digits almost like fingers in grooming and feeding operations.)
It is well known that the molariform teeth have been greatly modified for a special diet, and have departed strikingly from the mustelid type. Instead of the teeth having a shearing function, they are used for crushing, and have taken a bunodont form.
A most interesting feature of the sea otter dentition is the prevalence of cavities in the molariform teeth. Among the more or less fragmentary skulls and jaws found in Aleut village sites, a considerable percentage of the teeth had cavities, large and small. E. M. Fisher (1941) has given a detailed discussion of this and other features of the sea otter's dentition, and she intimates that rather active evolutionary changes may be taking place. She suggests that the difference in diet between the southern and northern sea otter may account for the greater prevalence of cavities in the teeth of the northern form. As interpreted by Fisher, the dental formula of the adult would be I 1,2,3-Cl-Pm 2,3,4-Ml I 1,2 -Cl-Pm 2,3,4-Ml,2 '
The sea otter is generally dark brown, with considerable variation, although this variation may be clue to age. Some old animals, as typified by the old male obtained by the writer at Ogliuga Island, are a dull, dark brown, becoming black on legs, but with a pale-brown head and neck —this pale coloration extends down on the chest, where it becomes almost straw-colored. The under side of the tail is paler than the body. White hairs are sprinkled throughout the pelage. In most of the darker animals these silvery hairs become more conspicuous. The younger adults are much darker, often blackish, with fine, lustrous fur.
The young pups are a very light brown. In every case, from the pup to the grizzled old male, the head and neck is paler than the body, and this difference is accentuated in the very old ones.
There is a voluminous literature on the habits of the sea otter, much of it largely repetition of what was reported by the earliest observers, including Steller. Only in the last few years have we begun to study the sea otter in any great detail, and there is much to learn. Therefore, I will not attempt to give a comprehensive life history of this interesting mammal.
Of chief interest to the biologist is the fact that this member of the weasel family has resorted to a marine environment and has gone a long way in adapting itself to a strictly aquatic life. It is interesting to note that, according to reports, the "land otter" of the Aleutian district readily takes to salt water at times ; apparently, this also is true of the otter of Great Britain.
The sea otter spends most of its time in the water. When wishing to sleep, it simply lies on its back and dozes, sometimes with a strand or two of kelp across the body serving as an anchor, whether intentional or not. When feeding, the animal dives for its food, then lies on its back to eat, using its chest for a table. On specimens from Alaska that were examined, the hair on the chest was somewhat worn, no doubt through this use in feeding. When the little pup wishes to sleep, it curls up on the mother's abdomen, and both mother and offspring lie quiescent on the water. The offspring also climbs aboard the mother to nurse.
When startled, the mother puts an arm around the little one and dives with it. On some occasions, the mother seemed to pat the little one on the head first, as if by this patting or pushing motion she were warning it of the impending immersion. This was never clearly seen, however, and it needs to be verified. If merely worried or suspicious, the mother seizes the pup with her arm and swims away with it.
Generally, when startled, the sea otter rises erect in the water for a better view of the intruder before diving. It swims readily on its back, as well as on its belly. In fact, the observer soon gains the impression that the sea otter spends most of its life floating on its back.
The sea otter does come ashore, however, and there are favorite hauling-out places for certain individuals. One or more mothers may climb out on a kelp-covered rock, with their youngsters, where they squirm about and fondle their little ones and end- lessly dress their fur. Sometimes a pup will wander off to the water, or will be reluctant to climb out on the rock. Then the mother persistently forces him, nudging and pushing, until he complies with her desire to haul out on the rocks. Occasionally, a male will join the group. We also saw lone individuals, apparently adult males, curled up on a rock, where they may lie long enough for the fur to dry. Even here, they appear restless, and may raise their heads to look about, yawn, rub their faces with their paws, or otherwise dress their fur. It is reported that sea otters go ashore in times of severe storms, but that sometimes they succumb in heavy surf on the reefs.
Sea otter breeding was observed once in Aleutian waters. It took place in the water, as the pair rolled over and over, sometimes being at the surface, sometimes underneath, the male grasping the female at the head with his teeth. This was on July 23, 1936, at a time when the female had a small dependent pup. The pup had been left at the outer edge of the kelp patch, where it swam about calling for its mother. This circumstance indicates that the female may breed in successive years. Scammon (1874) remarks that the gestation period is supposed to be 8 or 9 months. Probably it is fully that long.
Many observers agree that breeding may take place at almost any time of the year, because young of different ages can be seen at any season. Fisher (1940) appears to have definitely noted this during her research on the California sea otter. It is known that the young are born on the kelp beds, but in Alaskan waters, /where kelp beds disappear during the winter, the procedure is uncertain. Herendeen (1892) claims that the young are born at sea — he did not mention kelp beds.
It is well established that the northern sea otter feeds largely on sea urchins, and that this diet is supplemented by considerable quantities of mollusks, including mussels, chitons, limpets, snails, and others; and with lesser quantities of crabs, octopuses, and other items — fish play a minor role in the diet. More detailed analyses of the diet of the northern sea otter are given by Williams (1938), Barabash-Nikiforov (1935), and Murie (1940).
Although the sea otter has, to a large extent, forsaken fish as an important item in the diet, apparently it still enjoys such food on occasion. Chase Littlejohn (1916) reports an interesting incident: A sea otter was seen approaching his ship, but it dived. Presently, a fisherman pulled in a codfish and, as the fish came to the surface, the sea otter was seen clasping it in its paws.
One feature of the feeding habits deserves special mention, because it involves the use of tools. It was first seen in detail in California (Fisher 1939, and Murie 1940). Briefly stated, the sea otter dove for food and when it came to the surface the observer saw a rock lying on its chest or abdomen. The animal held a small mussel (or whatever the food morsel might be in such instances) in both paws and pounded it on the rock to break it. When feeding, the sea otter has a habit of rolling over occasionally in a complete turn, then continuing with its repast. Sometimes, it performs this roll with a rock and mollusk both on the chest. Naturally, it must clasp both of these objects to its body during the roll, but it does this very adroitly and casually, and it continues unconcerned with its meal.
The natural mortality factors affecting the sea otter are almost unknown. The northern bald eagle has been suspected of preying on young sea otters, and it is possible that this may occur on rare occasions. But it is notable that in our study of the food habits of this eagle (see under that species), not a single instance of such predation was found upon examination of eagle nests in the center of abundance of sea otters. It was concluded that eagle predation on the sea otter must be negligible.
Two mammals, the sea lion and the killer whale, have frequently been mentioned as sea otter enemies, but we had little opportunity to verify this. We rarely saw these animals near any sea otters, and although occasionally we saw killer whales cruising by the outer edge of a kelp bed, we could not identify its prey. However, the killer whale is known to eat fur seals, therefore it is reasonable to suppose that it will pick up a sea otter when the opportunity is presented. At any rate, the sea otter has demonstrated in recent years that it can increase in numbers and extend its range when it is protected from human hunters. Identification, and degree of predation, of its natural enemies must be determined by thorough scientific study.
It is a well-known fact that dead sea otters occasionally are washed up on the beach. On our expeditions, we found a number of skeletons on the beaches, from which blue foxes or eagles, or both, had eaten the flesh. It is said that a sea otter sometimes succumbs in the heavy surf in winter. Pups, as well as large adults, are included in casualties thus recorded on the beach. In
the postwar years a higher mortality rate has become evident and many dead sea otters have been found. The cause is not yet known.
From the evolutionary standpoint, the sea otter seems to be in an intermediate or transitional stage. The peculiar dental specialization has been mentioned, as well as the prevalence of cavities in the molariform series. These cavities are present in fresh specimens as well as in remains from old Aleut village middens. Fisher (1940) has reported an instance of gastric perforations in a sea otter found dead on a California beach.
One cannot refrain from speculating whether the specialization in food, which involves hard and sharp mollusk shells, tests and spines of sea urchins, barnacles, and similar materials that are ingested together with the soft digestible parts, are causing the sea otter some difficulty. Do some individuals succumb through injuries caused by such materials? How are the tissues responding to the demands for taking care of such rough fare?
It is obvious that the sea otter does not meticulously select only the soft parts. Apparently, it relies on crushing the shells with its teeth (and the teeth have developed enormously to meet the need) and then proceeds to swallow a considerable portion of shells, tests, and spines. Even the byssus of the mussel, often with pieces of stone or coral attached, is swallowed. In one instance, pebbles made up 21.8 percent of the contents of one scat. All such material passes through the alimentary tract, therefore it would not be surprising if serious injury occasionally resulted. It would be interesting to know how many of the sea otters washed up on the beach in Alaska have internal injuries similar to the gastric perforations reported by Miss Fisher.
On the other hand, from the standpoint of the sea otter population as a whole, the organism appears to be coping with the demands successfully. Rate of reproduction is slow — one young per year — yet, when released from the pressure of the fur trade, the sea otter has multiplied rapidly.
Distribution and Numbers
It is well known that in primitive times the northern sea otter ranged along all of the southern Alaskan coast, including the Aleutian chain and Alaska Peninsula. It ranged southward, evidently intergrading with the southern form at some unknown point, and the southern form ranged from this point southward as far as the coast of Baja California. The northern sea otter also occurred in the Commander Islands and southward into the Kurile Island chain, and they were numerous about the Pribilof Islands. Littlejohn (1916) reported schools of 400 sea otters in the early days of hunting along the Kuriles.
The decline of the sea otter population is a striking instance of the near extinction of a species through unregulated commercial exploitation. Before the coming of the white man, sea otters were extremely numerous and the skin was used by the Aleuts for clothing and (according to the chief of Atka Village) for a lining of the interior of their underground huts. We found Aleut mummies in a cave on Kagamil Island that w ere wrapped, in part, in sea otter skins.
When the Pribilofs were first visited, the sea otters were abun- dant. Preble and McAtee (1923), quoting Elliott and Littlejohn (1916), state that 5,000 sea otters were killed in the first year of occupation of the Pribilofs. Veniaminof , speaking of the Pribilof s, stated that the animals became scarce in 1811, and that they were extinct 30 years later (Preble and McAtee 1923).
In the Aleutian district, the Russians found a rich harvest of sea otter furs and exploited it vigorously. Without citing the voluminous statistics on the shiploads of furs sent back to Russia, let it suffice to say that the sea otter population could not stand up under the continued excessive harvest. History tells us that the Russians, sensing the end of a lucrative industry, attempted to regulate the killing of sea otters. But a new complication had entered the picture. Trading ships from the south had discovered this great fur resource— Americans, French, and others. Although the Russians could impose regulations on their own people, they found it hard to deal with this new foreign influx. The sea otters continued to decline in numbers and probably reached their low point shortly after 1900. When almost all were destroyed, protection was finally granted.
For years, the few remaining sea otters found a refuge in the Aleutians. Their status was hidden in the fog and mystery of this seldom-visited island chain, and for years naturalists feared that this animal species had disappeared from American fauna.
But, as mentioned above, complete protection had finally become a reality, and it soon became evident that the animal had survived in sufficient numbers to perpetuate itself. In spite of occasional poaching, in 1936 we found substantial sea otter populations in several places throughout the Aleutian chain, and we made a conservative estimate of at least 2,000. Most heartening of all, they were extending their range, not only in the Aleutians, but also along Alaska Peninsula. However, on our last visit to Sanak Islands the sea otters had not reappeared, although at one time this area was one of the best sea otter hunting territories (since our visit, five sea otters have been seen).
The range of the sea otter raises a puzzling point. There seems to be a difference of opinion as to the distance that the sea otter will venture from land. It is generally believed, and observations bear this out, that sea otters normally will live close to shore where they find their food in comparatively shallow water. Yet, there are reports of sea otters being seen far out at sea. On our expeditions, we never saw any of these animals far from land. However, at one time sea otters were numerous in the Pribilof Islands, and they must have made a long sea journey to reach these islands. After World War II, it was found that sea otters had increased still more and had extended their range.
Littlejohn (1916) believed that sea otters live on squids when far from land. He did not think that the otter could dive deeper than 60 fathoms, and because its normal sea-bottom diet was not available, it ate squid.
Sea Otter Hunting
At the height of the commercial exploitation of the sea otter, a number of hunting methods were used. The Russians utilized the skilled Aleuts for this purpose. The various methods have often been described, and the subject will be only briefly mentioned here.
One method was to spear the animal from the native boat. Several boats would surround the animal and keep it diving repeatedly until it was exhausted. In the meantime, spears were thrown until the animal was dead or helpless. Later, when the rifle was used, three boats would surround the otter, according to Little- john (1916). Here, too, the object was to keep the otter diving quickly, to prevent a long dive, until someone could manage an effective shot.
A dead sea otter will float, which insures recovery of an animal killed by any type of weapon. It is reported, also, that sea otters were sometimes clubbed to death on reefs or rocky shores, where they had taken refuge from severe storms. At such times, the noise of the wind and surf would drown out any sound of approach by the hunter. Littlejohn (Hall 1945, p. 90) has described how natives would creep around on the rocks during dark nights, feel for the otters, then club them on the head. Nets also were used. These nets were set in favorable locations frequented by sea otters, and, according to Littlejohn, they were very effective.
The encouragement of natives to secure sea otter skins on a large scale, promiscuous hunting by whites (who outfitted ships for that purpose) , combined with pelagic sealing, produced a large and profitable fur harvest for many years.
Sea Otter Management
The return of the sea otter in satisfactory numbers, at a time when we are being made conscious of wildlife management, makes the subject especially pertinent. In the case of the sea otter, the first step in management was to provide protection, and to encourage spread to all of its ancestral range. This process is now under way. From what we know of the food habits of the sea otter, the food supply should be ample to support a large population without artificial manipulation.
Apparently, the Russians are experimenting with, and studying, the sea otter of the Commander Islands (May 1943), and it is said that the Japanese have been managing the sea otters of the Kurile Islands on a commercial basis. The southern sea otter is increasing along the California coast. All in all, this interesting animal has already regained much of its lost range, and it can be assumed that it has attained a lasting place in the American fauna.