The National Marine Mammal Laboratory (NMML) has a long history of joint research on Steller sea lions in the Russian Far East. Beginning in the early 1990s, NMML scientists and scientists from TINRO (Russian Pacific Federal Fisheries Research Institute, Vladivostok) have worked collaboratively on joint surveys on Soviet scientific expeditions to the Kuril and Aleutian Islands to examine Steller sea lion rookeries and mark pups for estimation of vital rates.
In recent years, this work has continued in cooperation with the Alaska SeaLife Center, Kamchatka Institute of Geography of the Russian Academy of Sciences, and a number of other Russian scientific research institutes and organizations (Sevvostrybvod, TINRO, Komandorsky Reserve, Vyatskaya Agricultural Academy, Pacific Oceanological Institute) under the title of Project 02, "Marine Mammals," a section within Area V of the U.S.-Russia Agreement on Cooperation in the Field of Environmental Protection.
- Abundance Monitoring:
In Russia, aerial surveys of Steller sea lions are not possible due to the lack of appropriate aircraft and the absence of a sufficiently developed network of airports necessary to safely operate, refuel, and maintain planes. Therefore, rookery surveys intended to monitor changes in population trends are conducted from vessels and inflatable boats during the sea lion reproductive period (June–July).
Steller sea lions in Russian waters range over an extremely large area (Fig. 1), such that surveys are staggered among different areas in different years (Table 1). Results of surveys in adjacent years and adjacent areas are combined to determine total population in the region and to estimate trends. Results indicate that abundance varies in different areas (Table 1, Fig. 2).
Table 1. Counts of Steller sea lions in Russia, June–July 2001–08 (all sites, ages, and sexes combined).
Year
Western Bering Sea
Commander Islands
East Kamchatka
Kuril Islands
Tuleny, Sakhalin
Northern Sea of Ohkotsk
2001
946
748
6,840
1,160
3,683
2002
18
774
626
1,451
3,077
2003
746
6,775
1,599
2004
135
895
683
1,592
4,346
2005
7,685
1,625
2006
931
678
1,590
4,575
2007
10,185
2008
110
890
679
For example, in the western part of the Bering Sea, on the Commander Islands, and along the east coast of Kamchatka, the species' abundance has remained low with an insignificant downward trend after a sharp decrease in the 1980s. At the same time on the Kuril Islands, along the Sakhalin coast and in the northern part of the Sea of Okhotsk, the trend has been positive.
Collectively, data from 2006–08 suggest that about 18,000 sea lions haul out on Russian rookeries during the reproductive period (Table 1). Considering that during the direct survey approximately 30% of the juvenile and adult animals stay in the water and are not counted, the total population of Steller sea lions in Russia can be estimated to be approximately 25,000 animals.
Figure 2. Changes in abundance of Steller sea lions in Russia, 1960s–2000s (trend sites combined): NPSO = northern part of the Sea of Okhotsk;
Sakh = Tuleny Island, Sakhalin; Kurils = Kuril Islands; CI= Commander Islands; EK = East Kamchatka; WBS = western Bering Sea.
There is concern about the low number of breeding Steller sea lions on the coast of east Kamchatka and on the Commander Islands. Although the Commander Islands Steller sea lions inhabit Russian waters, they are genetically part of the western stock that ranges from the Commanders to Cape Suckling, just east of Prince William Sound. (continued)
