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Distribution and abundance of Steller sea lions, Eumetopias jubatus, on the Asian Coast, 1720's-2005.

Introduction

The Steller sea lion, Eumetopias jubatus, is widely distributed in the waters of the North Pacific Ocean and ranges along the west coast of North America from California to Alaska reaching the Bering Strait and the Asia coast. In Asia the range extends southward to encompass the coastal waters of the western Bering Sea, eastern Kamchatka, the Commander Islands, the Kuril Islands, the Sea of Okhotsk (including Shantarsky and Sakhalin Islands), Tatar Strait, around Hokkaido, and along the Asian coast of the Sea of Japan to the southern extremity of the Korean Peninsula, including Peter the Great Bay (Fig. 1, 2)(Scammon, 1874; Allen, 1870, 1880, 1892; Smirnov, 1908; Ognev, 1935; Nishiwaki and Nagasaki, 1960; Chapsky, 1963; Nishiwaki, 1966; Heptner et al., 1976).

Steller sea lion distribution throughout Asia is not uniform, occurring year-round in some regions and seasonally in others. In some regions, sea lions form large concentrations and in other regions they are sparsely distributed. Figure 2 shows all known Steller sea lion rookeries and haulout sites along the Asian coast over the last 263 years (1742-2005).

Their distribution on the Asian coast has varied significantly over this time period. Steller sea lions were numerous on Bering Island when discovered by George Steller in 1742, but they ceased breeding there and almost disappeared from the Commander Islands during the mid to late 19th century (Steller, 1751; Stejneger, 1898; Grebnitsky, 1902). They again became numerous and started breeding at the Commander Islands 100 years later, during the mid 20th century (Marakov, 1957, 1964; Muzhchinkin, 1964; Nesterov, 1964; Chugunkov, 1968, 1971, 1982, 1990; Pryanishnikov and Pinigin, 1972; Myrnrin and Phomin, 1978; Burkanov, 1986, 1988; Vertyankin and Nikulin, 1988). Steller sea lions were rarely sighted off Chukotka in the western Bering Sea in the 1930's, but were common there in the 1980's (Mymrin, 1991; Melnikov, 2001; Belopolsky (1); Freiman (2)). In the late 19th century to the early 20th century, Steller sea lions were common in Peter the Great Bay (Siberian coast of the Sea of Japan) (Ognev, 1935); however, as early as the 1930's their population was greatly reduced and by the late 20th century they were rarely seen in this region (Trukhin, 2001).

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As reviewed by Loughlin (1998), Steller sea lions are the largest of the sea lion and fur seal subfamily and show a marked difference in size of the sexes with males being from two to three times larger than females. Males can be as large as 1,120 kg and grow to 3.25 m long. Females average 250 kg and are about 3.2 m long. Pups weigh 16-23 kg, are about 1 m long at birth, and are quite docile.

Steller sea lions are not known to migrate, but they do disperse widely at times of the year other than the breeding season. Generally, animals up to about 4 years-of-age tend to disperse farther than adults. As they approach the age when they begin to breed, they have a propensity to stay in the general vicinity of the breeding islands, and, as a general rule, Steller sea lions return to their island of birth to breed as adults.

The breeding season extends from late May to early July throughout the range. Males establish territories in mid May on sites traditionally used by females for giving birth. Some copulations may occur at rest (haulout) sites between females not giving birth and by males which cannot hold territories on rookeries. Males are sexually mature by 3-7 years-of-age, but they generally are not physically large enough to establish and maintain a territory until 9-11 years-of-age; by 13-16 years-of-age they are too old and battered to maintain a territory. Females reach sexual maturity between 3 and 6 years-of-age and may continue to give birth to a pup until they are into their 20's. They give birth to a single pup. Females may nurse their pups from 4 months to 1-2 years, but pups are generally weaned just prior to the next breeding season.

This review analyzes published and archived records of Steller sea lion distribution and abundance in the Russian Far East for the past 260 years. Our review provides an assessment of changes in distribution and abundance along the Asian coast from the Bering Strait to the Korean Peninsula. The Steller sea lion range off the Asian coast covers a huge geographic area making comparative analysis of population dynamics throughout the range difficult. For example, of the 11 Steller sea lion sites known in the Commander Islands over the past 260 years, abundance data for the breeding season for a particular year or even over a decade are only available for 3-5 sites.

For our analysis, we grouped the Asian Steller sea lion data into seven regions including five breeding regions and two regions where sea lions rookeries are absent (the western Bering Sea and Japanese waters including the Asian coast of the Sea of Japan). The five breeding regions include the Commander Islands, eastern Kamchatka coast, the Kuril Islands, Sakhalin, and the northern Sea of Okhotsk (Fig. 3). The boundaries between these regions are somewhat arbitrary and sightings of marked sea lions indicate that they often move from one region to another, but during the breeding season those movements are minimal (Burkanov et al., 1995; Burkanov (3)).

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We made several assumptions during our reconstruction of the historical abundance of Steller sea lions in the northwestern Pacific Ocean for the past 260 years. The most important is that we combined results of reported data for specific sites and/or areas over several years or even decades. We did this because the existing data were typically not obtained during surveys designed to count sea lions, but for other purposes. These surveys were conducted in different years, by different people, and by various methods. Often the historical data were based on information from visiting scientists who relied on anecdotal information of local fishermen or hunters.

We also made some assumptions based on the sizes of rocks or beaches used by the animals for rookeries and haulout sites (e.g. Iony Island). It is important to note that we emphasized when data collected during the breeding season (June-July) were pooled. All abundance and reconstruction analyses presented in this review are based on direct count data only. We did not use correction factors to improve any count data, and our use of the terms "abundance" and "count" are identical unless stated otherwise.

History of Steller Sea Lion Research on the Asian Coast

George Steller described Steller sea lions as a separate species while serving as a naturalist with Vitus Bering, 1741-1742. Steller's report (Steller, 1751) contains detailed data on behavior, reproduction, abundance, and seasonal population fluctuations of Steller sea lions collected by him while marooned on Bering Island. Steller sea lion information was also collected by Stepan Krasheninnikov, a student of the Russian Academy of Sciences who had been sent to Kamchatka from the fall of 1737 through July 1741 to explore the unknown regions in the area (Krasheninnikov, 1755). Krasheninnikov's many trips around Kamchatka yielded much data on the plant and animal life of the Kamchatka Peninsula and also on the life and culture of the indigenous human residents of Kamchatka and neighboring islands. Other information supplementing Steller's description is found in the voyage logbook compiled by Sven Waxell (Waxell, 1940), another member of Bering's expedition.

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The Steller report (Steller, 1751) and materials from other members of the Bering expedition (Krasheninnikov, 1755; Waxell, 1940) provide insight into the distribution of the Steller sea lion during the second half of the 18th century. Records and archive materials are also available from the first hunting expeditions following the discovery by Bering of the route to Alaska. These records provide details of sea otter, Enhydra lutris, and northern fur seal, Callorhinus ursinus, harvests, which were of great commercial importance (Pallas, 1789; Berkh, 1823; Veniaminov, 1840; Efimov, 1948, 1950; Fedorova, 1985).

Documentation of the voyages of Russian ships to the Aleutian Islands and Alaska during the second half of the 18th century (Pallas, 1789; Berkh, 1823; Berg, 1929; Efimov, 1948, 1950; Zubkova, 1948; Makarova, 1968) make it clear that the major objective of the expeditions was the search for unknown islands and lands that were home to mammals of commercial importance, including sea otters and northern fur seals.

According to Russian regulations of the time, expedition organizers were official state representatives obliged to deliver to the exchequer the taxes (yasak) collected from the aborigines of the newly discovered islands. In addition, they had to pay a 10% tax from all commercial harvests. Accordingly, the historical archives contain information on almost every ship that visited Alaska, the Aleutian Islands, and Kuril Islands including the number of sea otter and fur seal pelts (but not Steller sea lions) taken for the exchequer and for the companies (Efimov, 1948).

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Despite its exceptional importance in the life of the indigenous people, the Steller sea lion was not highly valued by the Russians, and they did not pay any taxes on its harvest; thus, the magnitude of sea lion harvests was not reflected in their reports. At the same time, Pallas (1789) reported that while wintering on the Commander Islands before traveling farther east, the Cossacks "hunt various marine mammals, particularly Steller sea lions, whose meat is very tasty, and they take the skins of this animal along to the eastern islands." Hunting Steller sea lions without firearms was a labor-intensive and dangerous business (Steller, 1751; Krasheninnikov, 1755; Berkh, 1823; Waxell, 1940). Presumably, the Russian hunters traded sea lion skins for sea otter pelts to the Aleut natives who used them to build small skin boats (baidarkas).

Data on Steller sea lion distribution and abundance were rarely reported (Tikhmenev, 1861, 1863; Ditmar, 1901). An exception is the study by Bishop Innokenty Veniaminov (Veniaminov, 1840), which provides the most detailed account of the human residents of the eastern Aleutian Islands and also the distribution, abundance, and biology of numerous animal species, including the Steller sea lion. Veniaminov reported the decline in Steller sea lion abundance due to intensive harvest as early as the 1830's.

More evidence regarding the harvest of the Steller sea lion is found in the memoirs of Kirill Khlebnikov, the Alaska governor's assistant during 1817-1832 (Fedorova, 1985). Khlebnikov confirmed the report of a Steller sea lion harvest on St. George Island (Pribilof Islands) (Veniaminov, 1840). St. George Island residents were obligated to take 2,000 Steller sea lions per year to provide dry skins to be transported to Sitka Island for the manufacture of skin boats. At that time, large and small skin boats (baidaras and baidarkas) were the most important, and nearly the sole, means of transport used by Russian and indigenous residents to move between the islands and the Alaska coast. The reports by Federova (1985) and Veniaminov (1840) are important for the general understanding of the settlement of Alaska by Russian hunters and fur traders, the structure of pinniped and sea otter harvests, the number of vessels, types of transportation used by the indigenous people, and the administration of the huge region concerned.

A large body of data had accumulated on the morphology, biology, and distribution of Steller sea lions by the end of the 19th century. Allen (1880) stated: "Since the publication of my paper on Eared Seals, in 1870, our knowledge of this species has greatly increased, mainly through the published observations of Captain Scammon and Mr. H. W. Elliot.... Aside from Steller's early account of the northern sea lion, little had been published relating to the habits of this species prior to 1870. Now, however, with possibly one exception, none of our Pinnipeds is better known."

By the end of the second half of the 19th century, intensive and uncontrolled pelagic harvest of fur seals aroused concern on the part of a number of countries, primarily Russia, Japan, Great Britain, and the United States. A number of surveys of fur seal rookeries on the Commander, Kuril, and Tuleny Islands were conducted resulting in additional data on Steller sea lions (Bryant, 1870, 1890; Elliot, 1873, 1882; Voloshinov, 1887, 1889; Rosset, 1888; Slyunin, 1895; Stejneger, 1898; Grebnitsky, 1902). A succinct summary of Steller sea lions on Sakhalin Island was written by Nikolsky (1889).

Of particular importance are the publications by Captain Snow (1897, 1902, 1910) who engaged in sea otter and fur seal harvests on the Kuril Islands from 1873 to the end of the 19th century. He provided the location of the islands, a detailed description of Steller sea lion distribution, including 18 Steller sea lion rookeries, and other marine mammal breeding sites. Snow's publication is the first precise and most complete description of Steller sea lion rookeries in the North Pacific region. For instance, Steller sea lion rookeries on the Kamchatka coast (a more settled and accessible region than the Kuril Islands) were not described until the 1980's, 100 years after the work by Snow on the Kuril Islands.

The first Russian report to summarize available data on Steller sea lion morphology, biology, distribution, and population dynamics was by Smirnov (1908). It was followed by a series of more comprehensive reports that included the most inclusive data on Steller sea lions published in the late 19th to early 20th century (Shmidt, 1916; Kardakov, 1929; Dukul' et al., 1929), and also some valuable personal reports published by Ognev (1935).

The first systematic field surveys of the distribution and abundance of marine mammals, in particular the Steller sea lion on the western Asian coast, were conducted as late as the 1930's during a special scientific marine mammal hunting expedition by the Pacific Fishery Research Station (TIRKh, the predecessor of the Pacific Research Fisheries Center, TINRO) and the Moscow Research Institute of Fishery (the predecessor of the All-Russian Research Institute of Fisheries and Oceanography, VNIRO). In 1929-30, three researchers wintered at the villages of Tauisk, Siglan, and Yamsk on the northern coast of the Okhotsk Sea searching for marine mammals. In 1930, seven researchers stayed in the villages of Tigil, Ust-Bolsheretsk (western coast of Kamchatka), Karaga (eastern coast of Kamchatka), Anadyr, and Lavrentiya Bay (Chukotka).

Marine mammals were also surveyed by TIRKh fishery observers in the villages of Kichiga, Ust-Kamchatsk, Tilichiki, and in Shlyupochnaya Bay north of Olyutorsky Cape (Belopolsky (4)). These surveys yielded abundant data on the biology, distribution, and numbers of Steller sea lions off the Asian coast (Freiman, 1935a,b; Barabash-Nikiforov, 1935; Barabash, 1937; Belopolsky (1,4); Freiman (2); Lun' (5); Nikulin (6, 7, 8, 9); Pikharev (10)). Unfortunately, World War II (WWII) interrupted the surveys, which were not resumed until the mid 1950's. These later surveys focused on the restoration of northern fur seal and sea otter stocks and management of cetacean and phocid harvests. Special marine mammal laboratories were established for this purpose by TINRO in Kamchatka, Sakhalin, and Magadan.

In 1955, the Shirshov Institute of Oceanology, USSR Academy of Sciences, conducted a detailed survey of Steller sea lion rookeries on the Kuril Islands (Klumov, 1957a, b). TINRO was largely responsible for monitoring Steller sea lions and other marine mammals in the area (Belkin, 1965, 1966a, b; Perlov, 1970, 1974, 1975; Kuzin et al. 1977, 1984). Since the mid 1990's, integrated surveys organized by the Kamchatka Federal Department for Protection and Restoration of Fish Resources and Fisheries Regulations (Kamchatrybvod) and the Kamchatka Branch of the Pacific Institute of Geography, Far Eastern Branch, Russian Academy of Sciences, have been conducted to monitor Steller sea lions (Burkanov et al., 1995, 2002; Pavlov and Isono, 1999; Burkanov, 2000; Trukhin and Burkanov, 2002, 2004).

On the Commander Islands, marine mammals have been monitored by the Kamchatka Branch of TINRO and the Commander Island Fish Protection Inspection, Kamchatrybvod (Marakov and Nesterov, 1958; Muzhchinkin, 1964; Nesterov, 1964; Khromovskikh, 1966; Chelnokov, 1971, 1972, 1978, 1983; Mymrin et al., 1978, 1979; Vertyankin and Nikulin, 1988; Burkanov et al., 2003c; Marakov (11, 12); Nesterov (13); Khromovskikh and Tomatov (14); Khromovskikh (15, 16)). Since 1991, scientists of the Kamchatka Branch of the Pacific Institute of Geography, Far Eastern Branch, Russian Academy of Sciences, have been monitoring Steller sea lions on Yugo-Vostochny Cape, Medny Island (Mamaev and Burkanov, 1995, 1996; Mamaev et al., 2000; Burkanov, 2000; Burkanov et al., 2003a,b.). Members of the Komandorsky State Nature Reserve (Zagrebelny (17)) have participated in year-round monitoring of marine mammals on Bering Island since 1994.

Surveys on Tuleny Island (Sakhalin Island) were primarily conducted in summer by TINRO scientists (e.g. Kuzin and Naberezhnykh, 1991; Kuzin, 1996, 2001; Kuzin and Pavlov, 2000). In fall and early winter between 1977 and 1985, members of the Sakhalin Federal Department for Protection and Restoration of Fish Resources and Fisheries Regulations (Sakhalinrybvod) conducted surveys from aircraft during air patrols of the 200-mile economic zone of the U.S.S.R. (Annual report (18, 19, 20, 21)).

In Kamchatka, several local surveys (along the southeastern coast, Verkhoturov Island, and along the northeastern coast) of Steller sea lion rookeries were conducted from the 1960's to 1970's (Kharkevich and Vyatkin, 1977; Kasyanov (22); Chugunkov (23); Khromovskikh (15,16)), and a series of aircraft, boat, and ship surveys of Steller sea lion rookeries were made in the 1980's (Burkanov, 1986, 1988; Burkanov et al., 1988, 1990). These studies were followed by those of the Marine Mammals Protection Service, Kamchatrybvod. Until the 1980's, Chukotka and the northern Sea of Okhotsk received the least amount of study with regard to Steller sea lions (we could not find any publications on Chukotka between the 1930's and 1980's). However, in the 1980's and 1990's, Steller sea lion surveys were conducted in these areas (Maminov et al., 1991; Mymrin, 1991; Zadalsky, 1997, 2000, 2001, 2002; Grachev, 2000; Melnikov, 2001; Burkanov et al., 2002).

A number of large-scale concurrent Steller sea lion surveys were performed throughout the entire range by Russian and U.S. scientists (Perlov et al., 1990; Burkanov et al., 1990, 1991; Maminov et al., 1991; Loughlin et al., 1992; Burkanov et al., 2002, 2003a,b,c). A program of marking Steller sea lion pups in Russia was initiated in 1989 (Merrick et al., 1990; Perlov et al., 1990) which yielded further detailed data on sea lion movement and the structure of intra-specific groups of Steller sea lions (Burkanov et al., 1995; Kuzin, 1996; Kuzin and Pavlov, 2000; Kuzin et al., 2002, Trukhin and Burkanov, 2002, 2004; Altukhov and Burkanov, 2004).

Rookeries and Haulout Sites on the Asia Coast from the 18th to the 20th Centuries

Since Steller first described the Steller sea lion in 1751, over 130 rookeries and haulout sites have been identified on the Asian coast (Fig. 2, 4). The majority of these sites were described during the late 19th century and the early 20th century (Stejneger, 1887; Rosset, 1888; Nikolsky, 1889; Snow, 1897; Slyunin, 1900; Ditmar, 1901; Shmidt, 1916; Kardakov, 1929; Dukul' et al., 1929; Barabash-Nikiforov, 1935; Ognev, 1935; Sergeev, 1936, 1940; Nikulin, 1937; Belopolsky (4)). However, a number of sites were first reported in the 1950's-1980's (Averin, 1948; Klumov, 1957a; Gurvich and Kuzakov, 1960; Muzhchinkin, 1964; Nesterov, 1964; Perlov, 1983b; Burkanov, 1986, 1988; Mymrin, 1991; Marakov (12); Khromovskikh (15)). On the Kuril Islands, Belkin (1966b) divided Steller sea lion rookeries and haulout sites into several classes based on space available, frequency of use, and the number of animals using that space. Major rookeries and haulout sites were occupied constantly by about 400 animals, whereas minor sites were infrequently used and occupied by fewer animals, often based on weather and available prey. Major sites comprise rookeries (reproductive sites) and haulout sites (nonreproductive sites). Nonreproductive sites were subdivided into two subclasses with respect to sex and age: bachelor male sites and juvenile (both sexes) sites.

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Perlov (1980) distinguished only three types of sites (rookeries, juvenile sites, and bachelor sites) on the Kuril Islands with respect to sex and age composition of the individuals on land. However, he also indicated that his characterization of haulout sites was fairly subjective.

Over time, changes may occur in the use of a haulout site. Some sites change from rookeries into nonreproductive haulouts and vice versa (Perlov, 1980; V.N. Burkanov, personal observations). These transformations have been particularly rapid during the last 30 years due to the considerable decline in Steller sea lion abundance over the bulk of its range. Thus, the classification of Steller sea lion rookeries and haulout sites in our review relies on only two parameters proposed by Belkin (1966b), which we somewhat modified. One is the presence or absence of newborn pups at the site, and the second, constancy or duration of use by Steller sea lions. The following 4 criteria define terrestrial sites used by Steller sea lions in Russia.

1) Rookeries--sites where newborn pups occur during the breeding season ([greater than or equal to] 10 pups/year) in a protracted period ([greater than or equal to] 5 years),

2) Haulout sites--all sites where pups are not born or occur there irregularly (<5 years) and/or in small numbers (<10 pups/year),

3) Permanent sites--sites used regularly during a protracted period ([greater than or equal to] 10 years) year around or in a particular season, and

4) Temporary sites--haulout sites where Steller sea lions occur irregularly (not every year) or have been recorded only a few times.

According to the above classification, all rookeries are permanent sites and all temporary sites are haulouts (Fig. 4-6).

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Seasonal Patterns of Steller Sea Lion Distribution

Abundance of Steller sea lions in every region varies with the season. While on Bering Island, Steller (1751) wrote "They are found in this island in spring, as well as in winter and summer, but only in certain parts--those are rocky and near precipices. Nevertheless, others come here every year along with the sea bears (northern fur seals)." While on the Pribilof Islands, Elliot (1873, cited in Allen, 1880) reported, "The time of arrival at, stay on, and departure from the island is about the same [(as in the fur seal)]; but if the winter is an open, mild one the sea lion will be seen frequently all through it, and natives occasionally shoot them around the island long after the fur seals have entirely disappeared for the year. It also does not confine its landing to these Pribilof Islands alone ... it has been and is often shot upon Aleutian Islands and many rocky islets of the northwest coast ... they do not migrate back and forth every season." Allen (1880) distinguished the above feature of the Steller sea lion as one of its most important distinctions from the northern fur seal. Based on Charles Bryant's observation, Allen (1880) stated "Even after the breeding season they keep close to the shore near the breeding station until the severe weather of January. After this time they are seen only in small groups till the shores are free from snow and ice in the spring."

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The range of Steller sea lions along the Asian coast extends for 4,000 km (over 2,000 n.mi.) north-eastward and includes a variety of different climate conditions from season to season. Coastal waters are frozen during winter in the northern and western parts of the sea lion's range off Chukotka, eastern Kamchatka, Sea of Okhotsk, and Sakhalin. During harsh winters, the entire southern area of the Sea of Okhotsk, including the Lesser Kuril Islands and northern coast of Hokkaido Island, is covered by a dense ice layer.

The date when sea lions leave rookeries and haulouts varies with the onset of winter. Typically the onset of winter occurs in November-December off the Chukotka coast. Steller sea lions were recorded at a site until mid November (Mymrin, 1991), and mid December on the Yamsky Islands, Iony Island, and Tuleny Island (Kosygin et al., 1984). In general, these reports contend that in Asia, Steller sea lions do not haul out on land north of lat. 54[degrees]N during winter (Fig. 7), and they do not use haulout sites if blocked by ice.

In the early 1960's, development of fisheries and hunts of true seals (Phocidae) on ice resulted in observations of Steller sea lions at the ice edge in the Bering Sea (Tikhomirov, 1964a, b; Popov, 1982; Burkanov, 1988; Semenov, 1990; Mymrin (24)). The authors have seen aggregations of hundreds of Steller sea lions on the ice in the mid 1980's in Karaginsky Gulf and Olyutorsky Gulf in the area between Karaginsky Island and the eastern side of the Govena Peninsula. From an aircraft, Kosygin et al. (1984) watched 20 sea lions hauled out on the ice in the Shelikhov Gulf on 19 February 1982, and fishermen commonly report numerous groups of Steller sea lions wintering in the Sea of Okhotsk off the western shore of Kamchatka. Sea lions also occur there during winter far from shore in areas where polynyas persist and fishing vessels operate. Adult and subadult males are more abundant and seen more frequently on the ice than females and juveniles (Tikhomirov, 1964a, b; Popov, 1982; Perlov, 1983a; Calkins, 1998).

Steller sea lions occur off Hokkaido and haul out on rocks in winter and rarely in summer (Fig. 7) (Nishiwaki and Nagasaki, 1960; Itoo et al., 1977; Yamanaka et al., 1986). Seasonal differences occur in Steller sea lion abundance on rookeries and haulout sites on eastern Kamchatka, and several rookeries in the Kuril Islands (Fig. 8, 9), and at Nevelsk Port on the west side of Sakhalin Island (Belkin, 1966b; Perlov, 1970; Chupakhina et al., 2004). These observations also support the seasonal movements of Steller sea lions southward in winter. Based on his observations and evidence by local residents, Belkin (1966b) reported a marked seasonal pattern in the use of Steller sea lion rookeries and haulout sites on the Lesser Kuril Islands, believing that Steller sea lions migrate there from the more northerly Kuril Islands. Belkin (1966b) believed that a "substantial" proportion of Steller sea lions winter in the area of the summer rookeries and haulouts, but the winter distribution of Steller sea lions from the Kuril Islands remains obscure.

Regional Changes in Distribution and Abundance from the 18th to the 20th Centuries

Western Bering Sea

Summary of Surveys and Reports

Our analysis relies on published and unpublished data and personal communications with marine biologists, fishermen, and hunters collected during more than 20 years of marine mammal studies in the Russian Far East. There are no summary data available on the distribution, abundance, and exploitation of Steller sea lions in the western Bering Sea. Data collected by TIRKh coastal observers between 1929 and 1932 have been largely unpublished or were not preserved. In fact, we did not find any reports of fisheries observers from Shlyupochnaya Bay (Koryak coast), the villages of Kichiga (northern Karaginsky Gulf) and Tilichiki (Korf Gulf), nor can they be found in individual copies in the archives of TINRO or its branches, or in the personal archives of researchers (Belopolsky (1); Freiman (2); Belopolsky (4); Razumovsky (25, 26, 27)).

Pinniped haulout sites were monitored during a terrestrial survey in the 1950's in the Koryak National Okrug (Fig. 10) (Gurvich and Kuzakov, 1960). Their report lacks detailed information on the methods and dates, but it does include a useful list of Steller sea lion haulout sites in the region.

In 1962, Kasyanov (22) conducted the first census of marine mammals on some haulouts on the eastern coast of Kamchatka, including the western Bering Sea from Karaginsky Island to Vitgenshtein Cape. The data from that survey remained unpublished, but they are preserved in the TINRO archive.

In late May-early June 1968, Chugunkov (23) conducted a survey of pinniped haulouts in Karaginsky Gulf off Govena Cape, but his report was not published. His report (held in the Kamchatrybvod archive) contains data on Steller sea lion abundance on the islands of Karaginsky, Verkhoturov, and off Govena Cape.

In the 1970's, Vyatkin and Marakov (1972) and Kharkevich and Vyatkin (1977) worked on Verkhoturov Island for several seasons. Summary data on the distribution of Steller sea lions off Chukotka in the late 1970's are also available in the publication by Perlov (1983b). In 1979, Burkanov began working in Kamchatka and took part in nine complete surveys (1982, 1983, 1985, 1987, 1989, 1994, 1999, 2002, and 2004) and a number of partial surveys of the southern half of the Kamchatka coast. Only a small portion of these data have been published (Burkanov, 1986, 1988, 2000; Burkanov et al., 1990, 2003a).

In September 1991, Kitaev observed Steller sea lions on the haulout site at Krasheninnikov Cape. (3) From the 1980's to date, Kamchatrybvod Marine Mammal Protection Service has been conducting surveys of Steller sea lion haulouts in the western Bering Sea, and those data were given to us for analysis. From the early 1980's, Mymrin (1991, Mymrin (24)) worked in Chukotka and collected and published data on the distribution and abundance of Steller sea lions in the western Bering Sea. He told us that an Eskimo hunter in Chukotka killed a Steller sea lion with a plastic tag on its flipper which came from Kozlov Cape.

A detailed review of the recent (1990-96) distribution of Steller sea lions in Chukotka was performed by Melnikov (2001); information on distribution and abundance of Steller sea lions during winter in the western Bering Sea is also available (Tikhomirov, 1964a, 1964b; Popov, 1982; Semenov, 1990). Vertyankin and Kovalevsky (28) provide data on the abundance and age-sex composition of Steller sea lions off Cape Krasheninnikov on Karaginsky Island in November 1995 and 1996. Some data are available on the number of Steller sea lions taken as bycatch in the walleye pollock, Theragra chalcogramma, and Pacific herring, Clupea harengus pallasi, fisheries in Olyutorsky Gulf in 1991-92 and 2002 (Burkanov et al., 2006b, Burkanov et al. (29)).

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Distribution and Age-Sex Composition

Steller (1751) and Krasheninnikov (1755) stated that Steller sea lions do not occur north of lat. 56[degrees]N, but neither author provided evidence to support their conclusion. In the winter of 173940, Krasheninnikov made a trip from the mouth of the Kamchatka River (Nizhne-Kamchatsk) along the eastern coast to the mouth of the Karaga River. However, sea lions do not occur there near shore at that time of the year, so it is no surprise that he did not see them. Krasheninnikov (1755) described the daily life of the Koryak natives residing on Karaginsky Island, but he did not mention sea lions in his account. Steller could have received information from Vitus Bering or other participants in Bering's first voyage in 1728 when they discovered the strait between Asia and North America. A navigation log of the first voyage indicates that the explorers observed Steller sea lions near Navarin Cape (Fig. 10, site 6) located at lat. 63[degrees]N (Sopotsko, 1983) on 27-28 July 1728. We assume the information from the ship's log is more reliable than Krasheninnikov's and Steller's statements of the absence of sea lions north of 56[degrees]N.

Presently there is a sea lion haulout site near Navarin Cape and sightings of swimming sea lions near Bering's ship at this time of year was plausible. The absence of Steller sea lions north of lat. 56[degrees]N is one of several errors that occurred in Steller's publication, though they may not be Steller's error, but errors of those who compiled Steller's data from his field notes or a misprint (e.g. printed 56 instead 65). We conclude that in the first half of the 18th century, Steller sea lions inhabited waters of the western Bering Sea as far north as lat. 63[degrees]N.

Although Steller (1751) and Krasheninnikov (1755) indicated that Steller sea lions do not occur north of lat. 56[degrees]N, a navigation log of Bering's first voyage shows that sea lions were observed at lat. 63[degrees]N at Navarin Cape. In the late 19th century, Allen (1880) noted that the northern extent of the Steller sea lion range was obscure. Referring to W. H. Dall and H. W. Elliott, he proposed that Steller sea lions did not occur north of the southern ice edge (St. Matthew Island, roughly lat. 61[degrees]N).

[FIGURE 8 OMITTED]

However, in his section on Steller sea lion habitats, Allen (1880) included the "shores of the North Pacific, from Bering Strait southward to California and Japan" as the distribution range. Referring to Elliott (1882), Smirnov (1908) included the entire Bering Sea as part of the Steller sea lion range without giving any distribution details, and Ognev (1935) stated that the northern extent of the range was lat. 66[degrees]N (i.e. Bering Strait). It is difficult to under stand what evidence led Ognev to arrive at that conclusion. Presumably, he was guided by Allen's (1880) hypothesis or he had some further evidence he did not mention.

[FIGURE 9 OMITTED]

[FIGURE 10 OMITTED]

The first reliable evidence of the northern extent of the Steller sea lion's range in Asia is contained in the report by Belopolsky (1), a TIRKh (TINRO) coastal observer. He noted that according to Eskimos, Steller sea lions occurred "very rarely" on the Chukotka Peninsula (lat. 64[degrees]N), but "they know of these mammals." During Belopolsky's stay in that region (1930-31), Eskimos harvested two Steller sea lions off the northern coast of the Anadyr Gulf (Kresta Bay and Bering Cape, Fig. 10, site 5).

On 10 July 1931, Belopolsky (1) watched a Steller sea lion swimming off Meechkin Spit. He also reported a group of Steller sea lions hauled out on the pebble spit in Dezhnev Bay between Navarin Cape and Olyutorsky (sighted by the pilot, Landin, from an aircraft in 1930). However, the pilot likely mistook numerous largha seals, Phoca largha, for Steller sea lions in this area. Another TIRKh observer mentioned that one Steller sea lion was taken in Chukotka in the summer of 1929, but he also believed Steller sea lions to be an "occasional" species in that region (Freiman (2)). No evidence of Steller sea lions dwelling off the western and southern coast of Anadyr Gulf (Fig. 10) is available.

Belopolsky (4) studied marine mammal resources in the Karaginsky District of Kamchatka from August 1930 to October 1931 and reported that "... in the Region, I happened to sight the Steller sea lion on the islands Karaginsky and Verkhoturov. According to interviews, the Steller sea lion occurs off Nachikinsky Cape; and young lions, in Korf Gulf and off Govena Cape, if only rarely. On Verkhoturov Island, Steller sea lions haul out on the reefs of the southeastern aspect. This is the region's largest haulout, but its population does not exceed 50 individuals. Another haulout is in the south of Karaginsky Island, at Krasheninnikov Cape, with a population of no more than 15 individuals, which haul out at two sites on three cliffs. Steller sea lions haul out in the course of the entire summer and fall. According to Koryaks, there are no Steller sea lions in winter."

The available evidence suggests that in the 1930's, Steller sea lions occurred along the entire coast in the western Bering Sea from Karaginsky Gulf in Kamchatka to Bering Strait. Apparently the appearance of sea lions in Chukotka in the 1930's became more regular and frequent compared to the 1920's and earlier periods. In the 1950's, the southern part of the region (the Koryak coast) had at least five Steller sea lion haulouts, and their population was considerably higher than that reported in the 1930's (Gurvich and Kuzakov, 1960). These data corroborate data collected in September 1962 by Kasyanov (22) who surveyed six haulouts (Fig. 10, sites 7 and 10-14), but Steller sea lions were only present at three of them (Table 1, sites 8, 12, and 14). In March-June 1962 during an experimental harvest of true seals in the Bering Sea, Tikhomirov (1964a, b) observed large aggregations of Steller sea lions on the ice edge in the eastern Bering Sea (between the Pribilof Islands and St. Matthew Island) and in Olyutorsky Gulf. In May, both males and pregnant adult females were present (Tikhomirov, 1964a). He attributed the large number of Steller sea lions resting on the ice with the coincidence of foraging on herring schools along the southern ice edge.

In spring (late May-early June) 1968, Steller sea lions were seen at the haulout site at Verkhoturov Island and swimming off Govena Cape (they were absent from the haulout) and Krasheninnikov Cape, Karaginsky Island. At that time, there was still considerable ice in the southern Karaginsky Gulf. Mostly young individuals were observed hauled out on the Verkhoturov Island haulout site (Chugunkov (23)).

Steller sea lions occurred in small groups of up to 30 animals off Chukotka during summer-fall of the 1980's (Mymrin, 1991). They hauled out onto coastal cliffs at several sites along the southern side of the Chukotka Peninsula at Bering Cape and in Provideniya Bay (at Stoletiya Cape and Lesovsky Cape), Nuneangran Island, and also at walrus haulouts (Perlov, 1983b; Mymrin, 1991, Mymrin (24)). Steller sea lions of all ages, but primarily young males, occurred along the coast until late fall (November 1987) and were seen swimming and on the ice 36 km (20 miles) south of Chukotsky Cape (Mymrin, 1991).

When surveying Navarin Cape, we recorded a small group of young Steller sea lions on the reefs off Chesna Cape (Fig. 10, site 6) in June 1984. The operators of a nearby meteorological station located in Gavriil Bay reported that Steller sea lions hauled out there regularly throughout the summer. Farther south in Olyutorsky Gulf and Karaginsky Gulf, Steller sea lions were numerous during the entire ice-free period and hauled out on Karaginsky Island, Verkhoturov Island, around Olyutorsky Cape, and Vitgenshtein Cape (Burkanov, 1986, 1988; Burkanov et al., 1988, 1990).

During the Russian-American research cruise in March through April 1981, Steller sea lions were seen on the ice edge from Karaginsky Gulf to long. 178[degrees]W (Popov, 1982; Calkins, 1998). When denser ice fields were examined close to the shore between Cape Olyutorsky and Dezhnev Bay, Steller sea lions were not sighted (Popov, 1982). All animals harvested on this cruise (110 individuals) consisted of sexually mature males.

In the first half of the 1990's, single individuals or small groups of up to six Steller sea lions were sighted along the southern and eastern coasts of Chukotka (including Bering Strait) as early as late May (Melnikov, 2001). They were sighted less frequently in June, but counts increased again in July through August. Even though Steller sea lions were common in summer in Bering Strait and moved towards the Chukchi Sea, they were never sighted off the northern coast of the Chukchi Peninsula. Nevertheless, Melnikov (2001) proposed the northern extent of the Steller sea lion range to be north of Bering Strait (lat. 66[degrees]N), somewhere in the Chukchi Sea.

Prior to ice formation in fall, Steller sea lions occur frequently in groups of up to six animals off the southernmost part of the peninsula; that is, Chukotsky Cape (Fig. 10, site 2). It's very likely that these individuals are returning from the Chukchi Sea and Bering Strait (Melnikov 2001). The latest sighting of a Steller sea lion in that region was 25 December 1995.

In the late 1990's, no Steller sea lions were recorded on the haulout sites at Navarin Cape and Chesna Cape (Vaisman (30)). Along the Koryak coast and the northern half of eastern Kamchatka in the early 1990's, sea lions were a common species, occurring consistently on all haulout sites, but abundance was lower than in the late 1980's. Sea lions seen at Krasheninnikov Cape (Karaginsky Island, Fig. 10, site 14) in November 1995 and 1996 consisted of up to 50% sexually mature bulls, 30% young males (3-6 years old), and the remaining 20% included juveniles (1-2 years old) and pups (4-5 months old) with their nursing mothers (Vertyankin and Kovalevsky (28)). We found no records of Steller sea lions breeding in the Western Berning Sea region. All 15 sites are used as haulout sites by Steller sea lions during the ice-free season only.

Abundance

Data on Steller sea lion abundance in the western Bering Sea prior to the 1930's does not exist; the existing data show that abundance was relatively low during the 1930's. Sea lions were occasionally seen on the Chukutka coast in summer and were infrequently harvested by Eskimo hunters then (Belopolsky (1); Freiman (2)). Abundance along the Chukchi Peninsula and in Anadyr Gulf probably did not exceed several dozen or perhaps a hundred individuals, and there were no sites where Steller sea lions hauled out regularly.

South of Navarin Cape, Steller sea lions occurred more frequently. A haulout site did exist at Vitgenshtein Cape, but abundance data are lacking. In Karaginsky Gulf and Olyutorsky Gulf, Steller sea lions were common but at low levels of abundance. At least three Steller sea lion haulout sites existed (Verkhoturov Island, Krasheninnikov Cape on Karaginsky Island, and Nachikinsky Cape) where several dozen individuals hauled out in summer (Belopolsky (4)). Total abundance in the western Bering Sea in summer probably did not exceed 200-300 sea lions during the 1930's (Table 1).

By the mid 1950's Steller sea lion abundance increased in the southwestern Bering Sea. Up to 1,500 sea lions hauled out off Govena Cape in spring, up to 500 on Verkhoturov Island in summer, and over 200 in late summer on Krasheninnikov Cape on Karaginsky Island (Table 1). An estimated 50 individuals were at the small Nachikinsky Cape haulout site and several hundred to several thousand sea lions were estimated at the Vitgenshteyn Cape haulout site. Thus, in spring and summer the southwestern Bering Sea provided habitat for over 1,000 (and presumably several thousand) Steller sea lions.

In late May-early June 1962 and September 1968, two surveys of haulout sites were conducted. In the first survey, there were 113 sea lions on one haulout site at Verkhoturov Island, about 20 were in the water off Govena Cape, and 2 were sighted off Krasheninnikov Cape (Chugunkov (23)). During the second survey, Steller sea lions were seen on three haulouts (Krasheninnikov Cape on Karaginsky Island, Verkhoturov Island, and at Vitgenshtein Cape; Table 1) with a rough estimate of 1,000 sea lions (Kasyanov (22)) (and based on data obtained from interviews, up to 1,500 Steller sea lions were on Verkhoturov Island in May). Thus, at least 1,500 Steller sea lions were on haulout sites in spring during the mid 1950's and the early 1960's in northern Karaginsky Gulf (Gurvich and Kuzakov, 1960; Kasyanov (22)). In spring 1968, Steller sea lion abundance did not exceed 200 (Chugunkov (23)).

Few data are available for the area during the 1970's, but it is known that Steller sea lions continued to use haulout sites on Krasheninnikov Cape (Karaginsky Island) and Verkhoturov Island. Kharkevich and Vyatkin (1977) recorded up to 1,000 hauled out regularly on Verkhoturov Island in the mid 1970's, and Burkanov (3) found about 1,000 Steller sea lions on Verkhoturov Island in September 1979. There are no data on Steller sea lion abundance on Krasheninnikov Cape, but in the 1970's there were up to several hundred observed in the vicinity (Vyatkin (31)). A small number of Steller sea lions were also found at a haulout site on Nachikinsky Cape during the same time period (Bondarev (32)).

[FIGURE 11 OMITTED]

During summer (June through August) 1982-2004, 10 surveys were conducted covering the bulk of Steller sea lion haulouts in the southwestern Bering Sea (Table 2). Most animals were young males, but some adult females were seen nursing yearlings; no newborn pups were seen. Steller sea lion abundance in 1982 totaled about 5,000 animals and declined every year since; in 2002 only 18 individuals were counted (Fig. 11, Table 2). The 20-year decline was 99.7%, or 22.5% per year. Although Steller sea lion abundance in the western Bering Sea declined to only dozens of individuals in the summer of 2002 (Burkanov et al., 2003a,b), a boat survey in 2004 showed a slight increase to over a hundred individuals (Table 2).

The overall trend in Steller sea lion abundance in the western Bering Sea was low in the 1930's and they were considered rare along the Chukotka coast. By the mid 1950's abundance increased in Karaginsky Gulf and Olyutorsky Gulf to several thousand individuals. In the late 1960's, sea lion abundance in spring declined, only to increase again in the mid to late 1970's (Fig. 12). In the early 1980's, Steller sea lion abundance in summer was at least 5,000 animals, and they were common throughout the entire region, including Chukotka. During the last 20 years of the 20th century, Steller sea lions declined by 22.5% per year and by the early 21st century sea lion abundance decreased to about a hundred individuals, similar to the 1930's.

Commander Islands

Distribution and Age-Sex Composition

The earlier reports on the Commander Islands (Steller, 1751; Waxell, 1940) describe only habitat relief features that were important to Steller sea lions when forming rookery sites, but they do not specify locations of rookeries. The map drawn by Steller (1743) suggested that Steller sea lions were distributed in the southwest part of Bering Island (Steller called one of the local bays Sea Lion Bay). Steller (1751) also described the breeding behavior of Steller sea lions and documented a shared Steller sea lion and northern fur seal rookery on the southwest coast of Bering Island. The sea lion population on Bering Island increased in summer and breeding most likely occurred on the southwest side of the island in the vicinity of Gladkovskaya Bay, Lisinskaya Bay, and Manati Cape (Fig. 13, sites 19 and 20).

Participants of Vitus Bering's voyage did not visit Medny Island, but there is evidence from Pallas (1789) that Steller sea lions were there, at least in winter; no observations of sea lions breeding at the island were reported. Pallas (1789) states "In the fall Russian fur harvesters go to Bering and Medny islands where they stay for the winter. In the latter they hunt various marine mammals, especially Steller sea lion ..." Thus, in the mid 18th century, Steller sea lions also lived on Medny Island, at least in winter.

[FIGURE 12 OMITTED]

There is no information on the distribution and number of Steller sea lion rookeries on the Commander Islands in the first half of the 19th century, although the first permanent human residents arrived on the islands in 1805 to harvest fur seals there. According to Grebnitsky (1902), Steller sea lions had not been abundant in the Commander Islands since the mid 19th century. Stejneger (1898) visited the Commander Islands and all the existing fur seal rookeries several times in the late 19th century, but dedicated only a few lines in his large publications to Steller sea lions: "The sea lion was formerly quite abundant, but now become nearly extinct on both islands, though still numerous in certain localities on the Kamchatka coast. In 1895 I saw only one individual on Sivuchy Kamen' at Northern Rookery [(Yushina Cape)], Bering Island." Grebnitsky (1902) and Suvorov (1912) also stated that Steller sea lions occurred on the Commander Islands in greater numbers during winter than summer when only single individuals were present.

The reported low abundance of Steller sea lions on the Commander Islands continued until the mid 1920's. Marakov (1964) mentioned an unpublished report by Kulagin who wrote that in 1923, individuals and small groups of Steller sea lions were often seen at the northern fur seal rookery [(Yushina Cape)] hauled out at Sivuchy Kamen' (Fig. 13, site 16). Steller sea lion sites at Bering Island were located at Ariy Kamen', Manati Cape, and Yushina Cape, and at Medny Island only at Yugo-Vostochny Cape (Fig. 13). Ognev (1935), referring to Kardakov, stated: "To Bering Island Steller sea lions come (on average) in October to stay till March. Prior and after that period their abundance is low, but in the summer, near fur seal rookeries it is always possible to see individuals, mainly young ones, of 1-2 years. At Bering Island, Steller sea lions formed haul outs in winter on Manati Cape (southern extremity of the island) and partly in the Gladkovskaya Bay (around it, to be exact), a bit to the north of Manati Cape on the west side. There they stay in low abundance. Their population on Manati Cape is about 500-1,200. On Medny Island they concentrate in winter at the south-east extremity (fur seal rookery) and reach up to 2,000 heads." In addition to the three sites mentioned by Kardakov (Ognev, 1935), Barabash-Nikiforov (1935) reported winter haulout sites at Ariy Kamen' (northwest extremity of Bering Island) and the northwest coast of Medny Island. Both authors state that only males are harvested at the islands; one female was killed by a local hunter in April 1932.

During the early 1920's to the late 1930's, Steller sea lions were sighted on Bering Island at Ariy Kamen', Gladkovskaya Bay, and Manati Cape, and on Medny Island at Yugo-Vostochny Cape and Sivuchy Kamen' (little island in Bobrovaya Bay on the northwest coast; Fig. 13, site 21).

[FIGURE 13 OMITTED]

Few data exist on Steller sea lions in the Commander Islands from the 1930's through the 1950's, but in the mid 1950's through the early 1960's, the principal haulout sites were similar in number and were located in the same sites as in the 1930's (Marakov, 1964, 1972; Muzhchinkin, 1964; Nesterov, 1964; Khromovskikh, 1966; Chugunkov, 1968, 1971, 1982; Marakov (11, 12); Nesterov (13)). Marakov (1964) and Nesterov (1964) mentioned two additional haulout sites at Medny Island at Kosoy Kamen' Rock off the west coast, and at Cherny Cape on the east coast. They did not state when these haulouts were established, but from the context we assume they existed through the 1950's and early 1960's.

After nearly a century (about 1850-1950) of low abundance, Steller sea lions reappeared on the islands in summer in the mid 1950's. They formed more or less regular haulouts on five sites at Bering Island, including Yushina Cape, Severo-Zapadny Cape, Ariy Kamen' Island, Gladkovskaya Bay, and Manati Cape, and at five sites on Medny Island, including Yugo-Vostochny Cape, Kosoy Kamen', Sivuchy Kamen' (Bobrovaya Bay), Sivuchy Kamen' (Zhirovskaya Bay), and Cherny Cape (Fig. 13). Steller sea lions hauled out year-round at Manati Cape (Bering Island) and at Yugo-Vostochny Cape (Medny Island). The remaining sites were mainly used in the winter.

In the late 1970's, the distribution pattern of Steller sea lions at the islands changed again when sea lions stopped using haulout sites at Cherny Cape and Kosoy Kamen' on Medny Island. Since 1978 they ceased using the haulout site in Gladkovskaya Bay on Bering Island, and since 1983 they ceased using the haulout site at Sivuchy Kamen' (Bobrovaya Bay) on Medny Island (Vertyankin and Nikulin, 1988). At about the same time, sea lions disappeared from the Sivuchy Kamen' haulout on the east coast of Medny Island, whereas the haulout at Yugo-Vostochny Cape (Medny Island) became a rookery, and the number of pups started to increase (Chelnokov, 1983). In the early 1980's, pups (2-33 pups per year) were born at Manati Cape, Bering Island. By the mid to late 1980's Steller sea lions used three haulout sites and one rookery at Bering Island and the Yugo-Vostochny Cape rookery on Medny Island (Fig. 13). From the 1980's to the present, all age and sex classes of Steller sea lions have been present year-round on the Commander Islands.

[ILLUSTRATIONS OMITTED]

Pup production ceased at Manati Cape (Vertyankin and Nikulin, 1988; Burkanov, 2000; Burkanov et al., 2003a) and had not resumed as of 2005. All other Steller sea lion locations remained the same as in the late 1980's except for the haulout that was reestablished near the northwestern tip of Medny Island on Bobrovye Rocks (Fig. 13, site 21).

Steller sea lions have inhabited the Commander Islands year-round for the past 260 years, although seasonal changes in abundance and age and sex structure of hauled out animals has occurred. In the 18th and 19th centuries, Steller sea lions bred on both islands; since the mid 20th century, sea lions bred regularly only at Medny Island. A few new-born pups have been sighted irregularly and in low numbers at Bering Island haulout sites in the late 20th century.

Abundance

Non-pup Population data for Steller sea lions on the Commander Islands are only available since the 1930's (Table 3). The data were obtained from various published and archive sources and require some clarification. In most cases the animals were censused at different haulouts by different observers coincidental to fur seal studies. Table 3 contains data for years when surveys were conducted in a majority of the region's haulout sites that could be estimated from surveys conducted in other years.

In the 1930's, during late fall and winter, there were 2,000-3,000 Steller sea lions present (Barabash-Nikiforov, 1935; Ognev, 1935), but Barabash-Nikiforov (1935) noted that with the onset of the breeding season almost all sea lions left the islands; only sea lions that were on the haulouts with northern fur seals remained. According to Chugunkov (1968) there were five Steller sea lions at the Uril'e haulout on Medny Island in summer 1930. The picture by A. I. Kardakov, published by Ognev (1935), shows two Steller sea lions in July 1930 at the fur seal rookery at YugoVostochny Cape, Medny Island.

[FIGURE 14 OMITTED]

Marakov (1964) mentioned that during 1935-1941, free-ranging Arctic fox, Alopex lagopus, farms were active on both islands. To provide food for foxes the Aleut hunters shot Steller sea lions when possible. Although sea lions were taken by hunters and disturbance was high, sea lion numbers slowly increased. Marakov (1964) reported sharp increases in Steller sea lion abundance on the Commander Islands during WWII and soon after (1942-50). During the mid 1950's, sea lions occurred on the islands year-round. Marakov (1964) estimated their number at 4,000-4,500 animals, but actual count data in summer did not exceed 3,050 individuals (Marakov, 1964; Nesterov, 1964; Muzhchinkin, 1964; Chelnokov, 1978; Marakov (11, 12), mostly hauled out on Medny Island (Table 3).

Steller sea lion abundance was highest in winter-spring, but in the early 1960's, Steller sea lions were seen more frequently at the haulout sites on Bering Island in summer. Muzhchinkin (1964) reported that in 1961, 15 Steller sea lions hauled out on Yushina Cape and up to 250 hauled out on Bering Island at Severo-Zapadny Cape (in late summer). A haulout site with 200 Steller sea lions was at the southern end on Manati Cape. Steller sea lion abundance in summer on the Commander Islands during late June 1962 was estimated at roughly 3,000 individuals (Table 3, Fig. 14) (Muzhchinkin, 1964), and females were becoming more frequent (Nesterov (13)). A survey of all haulouts in March-April 1965 produced an estimate of 10,000 sea lions (Table 4); a census of the same haulouts in summer yielded only 2,300 (Khromovskikh, 1966). In February 1968, 10,850 Steller sea lions were counted (Table 4), whereas in September, 1,742 were counted (Mymrin and Phomin, 1978).

Two aerial surveys of the Commander Islands were conducted (Khromovskikh (15,16)), the first was on 12 June 1971. Estimated sea lion abundance was 2,370-3,470 animals (mean = 2,920). The most important aspect of this survey is that all known Steller sea lion haulouts were surveyed in one day. In addition, the mean value of the aircraft census of Steller sea lions on Cape YugoVostochny, Medny Island, was similar to the counts (mean = 1,207; range = 1,217 -1,233) of three land surveys conducted at about the same time as the aerial survey (Chelnokov, 1978; Chelnokov (33)). The second aerial survey occurred in 1973 (Khromovskikh (16)). Unfortunately, the report lacks data on Steller sea lion abundance at Cape Yugo-Vostochny. Aircraft survey data coupled with the coastal census on Yugo-Vostochny Cape by Chelnokov (1978) yields an estimate of 3,503 individuals in late June-early July 1973 (Table 3).

We obtained census data for 1977 from a variety of sources (Chelnokov, 1978, 1983; Mymrin and Phomin, 1978; Vertyankin and Nikulin, 1988) which indicated high abundance of Steller sea lions on Manati Cape. The earliest census was on 24 May, considerably earlier than censuses at other haulouts or during the preceding years. Unfortunately this haulout site was not surveyed later in June-July. If this difference is ignored, 1977 had the greatest Steller sea lion abundance at haulout sites in summer amounting to about 5,000 individuals. For the first time, the number of Steller sea lions on Bering and Medny Islands in summer was almost equal to winter abundance.

By 1978, there were changes in seasonal population dynamics of Steller sea lions on the Commander Islands. The census conducted at the same March-April dates as in 1965 demonstrated a sharp decline in sea lions wintering on the islands. The count in 1978 totaled only 2,646 sea lions, which was about one-third of the estimates in 1965 (10,040 animals) and 1968 (10,850 animals) (Table 4). A similar number of Steller sea lions (~2,600) remained on the Commander Islands in the summer of 1978. Steller sea lion abundance then declined until 1982 by an average of 17.3% per year (Table 5). The decline occurred primarily on Medny Island. Between 1982 and 1986, abundance in summer increased by 67.0%, or 10.4% per year during summer (Table 5). From 1986 to 1994 the abundance of Steller sea lions on the Commander Islands during the breeding season dwindled again by 79.3% (17.3% per year). The greatest decline (46.1%) occurred in the winter 1987-88 and the rate of decline was much lower in subsequent years. After 1988, no noteworthy differences in the abundance of Steller sea lions between winter and summer were recorded. In contrast, their numbers during the breeding season were somewhat higher than in winter or spring (Table 3, 4), suggesting that unlike the seasonal pattern observed during 1910-30's, some Steller sea lions breeding on the Islands migrated to other regions in winter.

Between 1994 and 1998, Steller sea lion numbers increased during the breeding season by 65.4% (13.0% per year; Table 5). The greatest increases in sea lion numbers occurred in 1995 and 1996 (20.0% and 23.1%, respectively). From 1998 to 2004, the number of Steller sea lions declined by 25.1% (7.1% per year). A spring survey conducted in late March-early April 2005 indicated patterns of seasonal abundance were similar to those in the late 1970's through 1990's; the number in winter and spring was slightly lower than in summer (Table 4) (Purtov and Burkanov, 2005).

Pups From the mid 19th century to 1962, Steller sea lions did not breed on the Commander Islands (Grebnitsky, 1902; Barabash-Nikiforov, 1935; Muzhchinkin, 1964); the first pup was recorded on 4 July 1962 at the YugoVostochny Cape rookery on Medny Island (Muzhchinkin, 1964), but none were observed over the next 7 years, although some instances of mating and abortions were recorded (Chelnokov, 1971; Chugunkov, 1990). Pups have been born every year on Yugo-Vostochny Cape, Medny Island, since 1969 (Chelnokov, 1971; 1983). On Bering Island, three newborn pups were first sighted on Manati Cape in 1982 (Table 6). Pups were regularly sighted at that rookery (i.e. 30 pups in 1987) until 1991, but since then no sea lion pups have been born at the Manati Cape haulout site (Vertyankin, 1986; Vertyankin and Nikulin, 1988; Burkanov et al., 2003a). One pup was born for the first time on Severo-Zapadny Cape in 1986, two pups were seen on Ariy Kamen' in 1999, and one pup was seen on Yushina Cape in 2000 (Chugunkov, 1990; Vertyankin (34)). Although pups were sighted at all four currently active haulout sites on the Commander Islands, presently the only major rookery is on Yugo-Vostochny Cape, Medny Island. The number of pups that appeared at the Commander Islands rookeries and haulouts between 1962 and 2005 is presented in Table 6 and Figure 14.

The number of pups born on the Commander Islands increased rapidly through immigration from 3 in 1970 to 236 in 2005. Numbers have fluctuated slightly with a peak of 280 in 1998, but the overall trend is increasing (Table 6).

Eastern Kamchatka

Distribution and Age-Sex Composition

Steller sea lions were first reported from the Kamchatka Peninsula by Steller (1751) and Krasheninnikov (1755): "They are hunted a great deal near Kronotsky Cape and around the island near the mouth of the Ostrovnaya River, around Avacha Gulf, and from here as far, as Lopatka Cape ... The sea lion is never seen in the Penzhin Sea. The reason why these beasts come hither (to the Commander Islands, VB) in June, July, and August, are for parturition, for rearing and teaching the pups, and for copulation. Before and after this period they are found in greater numbers on the shores of Kamchatka."

Major sites where Steller sea lions occur adjoin steep cliffs along the Kamchatka, Kronotsky, and Shipunsky Peninsulas, and along the southeastern Kamchatka coast (Fig. 15). This region has 16 Steller sea lion sites (Steller, 1751; Krasheninnikov, 1755; Ditmar, 1901; Shmidt, 1916; Nikulin, 1937; Sergeev, 1940; Averin, 1948; Kuleshov, 1950; Burkanov, 1988; Khromovskikh (14, 15)), but most are inaccessible to humans or terrestrial predators.

Few data are available on age and sex of Steller sea lions occurring on eastern Kamchatka shores. From descriptions of the hunting practices of indigenous people by Krasheninnikov (1755), we conclude that adult males were common there, but so were young individuals through historical times (Ditmar, 1901). Information on the presence of females and pups is available from the early 20th century (Shmidt, 1916). We note that during the last 100 years all ages and sexes of Steller sea lion were present year-round in this area (Shmidt, 1916; Nikulin, 1937; Sergeev, 1940; Averin, 1948; Kuleshov, 1950; Burkanov, 1988; Burkanov et al., 2002, 2003a). There are three breeding sites located at Kamchatsky Cape (Fig. 15, site 29), Kozlov Cape (site 31), and around Shipunsky Peninsula (sites 33, and 34).

The literature and archive information indicate that few changes in sea lion distribution occurred in the Kamchatka region over the last 260 years. However, the number of sites used in the area changed considerably over time. When sea lion abundance was high, there were more active sites, whereas during low abundance the number of sites decreased.

Seasonal patterns

Steller sea lions occur year-round off eastern Kamchatka even though abundance varies seasonally with high numbers in spring, summer, and fall, and low numbers in winter (Fig. 8). The eastern Kamchatka coast is characterized by cold winters with abundant snow, and in November, as ice forms on the cliffs used as haulout sites, sea lions abandon these sites. Until the mid 1980's sea lions were observed regularly at most sites off southeastern Kamchatka (Fig. 15, sites 33-43). Since 2000, they have been observed only during winter at three sites on Shipunsky Cape, Avacha Bay, and Kekurny Cape (Fig. 15, sites 34, 36, and 39). During inclement weather conditions the animals cross over iced coastal reefs onto the mainland where they are protected from strong winds and high waves. In late winter drifting ice appears, but sea lions are still present. During heavy storms, Steller sea lions are commonly blocked on shore by a zone of storm-pressed compact ice stretching from shore to open water for several miles. Steller sea lions do not use in winter haulout sites north of Shipunsky Peninsula (Fig. 15, sites 27-32) except during very warm and calm winters when they occur along the shore and occasionally are sighted on the offshore ice.

[FIGURE 15 OMITTED]

Abundance

Non-pups The Kamchatka Peninsula was a starting point for many historical expeditions for the discovery of "new lands," and a number of distinguished researchers visited this area but failed to leave any quantitative information on the abundance of Steller sea lions in the region in the 18th-19th centuries. Published data provides evidence that Steller sea lions were fairly numerous off eastern Kamchatka in the first half of the 18th century (Steller, 1751; Krasheninnikov, 1755; Ditmar, 1901; Grebnitsky, 1902). According to Krasheninnikov (1755) they were regularly harvested by indigenous people of Kamchatka (Kronotsky and Shipunsky Peninsulas).

The geologist Karl Ditmar (1901) made a complete report of his stay in Kamchatka in the mid 19th century. He observed that Steller sea lions hauled out at Shipunsky Cape, Olga Cape, Kozlov Cape, and in Zheleznaya Bay (Fig. 15). Ditmar's data suggest only a small number were present at most sites during his June-July observation period. Ditmar's (1901) data suggest that in the mid 19th century Steller sea lion abundance on eastern Kamchatka shores was not high. It is worth noting that Steller sea lions stopped breeding on the Commander Islands during the same time period (Grebnitsky, 1902).

[ILLUSTRATIONS OMITTED]

Shmidt (1916) reported that Kamchatsky Cape was a rookery after visiting there in early June 1908 (Fig. 15, site 29). His characterization of the site as a rookery was based on the physical size of the hauled out sea lions, their behavior, the presence of newborn pups and decomposing placentas. The high abundance of Steller sea lions on the Kamchatka coast in the early 20th century is supported by data on the harvest of 600 newborn pups at Kozlov Cape in 1920 (Averin, 1948).

The first quantitative data used to estimate total Steller sea lion abundance off eastern Kamchatka dates back to the 1940's when abundance (reported as maximum counts) was provided by local hunters to Averin (1948) as roughly 5,000-7,000 sea lions. This estimate is equivocal when compared to the count at Shipunsky Peninsula (Fig. 15, sites 33 and 34) in 1940 (Averin, 1948) was 4,000-5,000 individuals; Nikulin (1937) reported 500-600 for the same site in late July 1935. Nikulin also noted that with the exception of Shipunsky Cape, only a few individual Steller sea lions occurred along the rest of the eastern coast of Kamchatka. This statement does not seem accurate either, however, because over 1,400 Steller sea lions were observed at Kozlov Cape in 1942 (Averin, 1948). Apparently sea lion abundance varied considerably over time, and the hunters who reported their estimates to Averin provided maximum values observed per year, whereas Nikulin stated results of a single survey at Shipunsky Cape during a harvest by the sealing ship Nazhim (Nikulin, 1937). Despite these differences, Averin's data appear to provide a comprehensive insight into the total Steller sea lion abundance in the region during the 1930's and early 1940's.

[FIGURE 16 OMITTED]

Comparable data on Steller sea lion abundance off eastern Kamchatka during the breeding season are available since the 1980's (Burkanov, 1986, 1988, 2000; Burkanov et al., 2002, 2003a). Over a 21-year period (1983-2004), nine complete surveys were conducted (Table 7; Fig. 16). In 1983, Steller sea lion abundance was roughly 2,000 animals and by 2004, abundance declined fourfold to about 500 sea lions (73.6%, or 6.3% per year). Between 1983 and 1994, sea lion abundance declined at a greater rate (10.8% per year). Subsequently, between 1994 and 1999, the trend in abundance increased 12.1% (2.3% per year). After 1999, sea lion abundance declined again. The decline over the next 5 years (1999-2004) was 23.9% (6.2% per year).

Pups The first available data on Steller sea lion pup production on eastern Kamchatka were reported by Shmidt (1916) who observed pups at Kamchatsky Cape in early June 1908. Nikulin (1937) provided numbers of Steller sea lion pups harvested (30 individuals) by the sealing ship Nazhim in early July 1935 off Shipunsky Cape. Averin (1948) discussed in detail the harvest of Steller sea lion pups on Kozlov Cape in early July 1942 and provided data on the history of harvests of Steller sea lions at that site between 1919 and 1942 (Table 8). Generally, these reports provide evidence that total sea lion pup abundance during 1910-40 off eastern Kamchatka was about 1,000 (600 pups were taken on Kozlov Cape only in 1919). At that time there were large rookeries situated at Kamchatsky Cape, Kozlov Cape, and around Shipunsky Peninsula (Shmidt, 1916; Nikulin, 1937; Averin, 1948). According to Averin (1948) and Kuleshov (1950), the total Steller sea lion abundance (and particularly the abundance of young animals) declined as early as the mid 1940's due to the intensive and unregulated harvest of pups. Kuleshov (1950) reported that in early July 1946 he saw no pups around Shipunsky Peninsula because all had been killed by hunters.

[FIGURE 17 OMITTED]

We found no quantitative data on pup abundance off eastern Kamchatka between 1946 and 1987 in the literature or available archives. Long-term population changes in sea lion pups can only be found for a rookery at Kozlov Cape (Fig. 17). However, the estimate (600 pups) for 1920 reflects the number of pups taken at that rookery (Averin, 1948). Considering the limited number of sites suitable for breeding at Kozlov Cape, it appears unlikely that the abundance of pups was much higher than the reported harvest level. Presumably, in 1920 the entire pup population was killed. Thus, over the last 82 years (1920-2004) the abundance of newborn Steller sea lions at Kozlov Cape has declined from 600 individuals in 1920 to 107 in 2004 (82.5%). The total rate of decline averaged 2.3% per year, but was not uniform over time. Between 1920 and 1942, pup abundance declined by 50% (3.1% per year), and subsequently (1942-87) declined by another 30%. However, the total rate of annual decline was low, constituting less than 1% per year. Between 1987 and 1994, pup abundance declined by 55.9%, which was the largest over the entire period, averaging 10.7% per year. Between 1994 and 2004, pup abundance did not change dramatically in this region, and the last few years have resulted in a positive trend (Table 8).

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Title Annotation:Part 1
Author:Burkanov, Vladimir N.; Loughlin, Thomas R.
Publication:Marine Fisheries Review
Article Type:Author abstract
Geographic Code:90ASI
Date:Mar 22, 2005
Words:11667
Previous Article:Errata.
Next Article:Distribution and abundance of Steller sea lions, Eumetopias jubatus, on the Asian Coast, 1720's-2005.
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