Trends in abundance of Steller sea lions and northern fur seals across the North Pacific Ocean

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1 Trends in abundance of Steller sea lions and northern fur seals across the North Pacific Ocean Rolf R. Ream National Marine Mammal Laboratory, NMFS, Seattle, WA Vladimir Burkanov Natural Resources Consultants, Inc., Seattle, WA

2 Steller sea lion and northern fur seal range Steller sea lion range Northern fur seal range

3 Yellow dots = Steller sea lions Pink dots = Northern fur seals

4 Pribilof Island northern fur seal at-sea distribution Winter Summer Migration Breeding (November-June) (June-November)

5 Steller Sea Lion Rookeries and Stock Structure Eastern Stock Thousands SE AK BC OR & CA

6 Non-Pup Steller Sea Lion Counts 8, 7, 6, 5, 4, 3, 2, 1, Kenai-to-Kiska Rookeries Trend Rookeries and Haulouts All Surveyed Sites

7 Non-Pup Steller Sea Lion Counts 2% % % 8% % -4% -6% -8% -1% -12% -14% 6% 4% 2% % -2% -4% -16% Aleutian Islands Gulf of Alaska Western Central Eastern Western Central Eastern -6% Aleutian Islands Gulf of Alaska Western Central Eastern Western Central Eastern Annual Rates of Change Mean ± 95% CI

8 Historic Changes in Distribution and Abundance of Steller Sea Lions in the Western Pacific, 17s 22 Steller sea lion rookeries and houlouts along Asia coast, 17s-22

9 Steller sea lion rookeries and haulouts along Asia coast, 17s-22 Counts at 6 trend sites in the WBS, age 1+ 6, 5, 4, 3, 2, 1,

10 EK: ABUNDANCE & TRENDS, : Counts at 8 trend sites in EK, (age 1+) N u m b e r, a g e 1 + 2,5 2, 1,5 1,

11 CI: ABUNDANCE & TRENDS, : Counts of SSL in Commander Islands, (age 1+) 6, 5, 4, 3, 2, 1,

12 Kuril Islands trend sites: Historic Changes in Distribution and Abundance of Steller Sea Lions in the Western Pacific, 17s 22 Steller sea lion abundance in Kuril Islands, , 2, 15, Individuals 1, 5, 1, 8, 6, 4, 2,

13 Historic Changes in Distribution and Abundance of Steller Sea Lions in the Western Pacific, 17s 22

14 Historic Changes in Distribution and Abundance of Steller Sea Lions in the Western Pacific, 17s 22 Tuleny I Non-pup NON-PUP

15 Historic Changes in Distribution and Abundance of Steller Sea Lions in the Western Pacific, 17s 22 THE NORTHERN PART OF THE SEA OF OKHOTSK: Total abundance

16 Reconstructed Steller sea lion abundance along Asian Reconstructed Steller sea lion abundance along Asian coast, coast, , 3, 1, 25, 2, 8, 15, 6, 1, 5, 4, 2, 196s 197s 198s 199s 2s 189s 191s 193s 196s 198s 2s

17 Summary of SSL along the Asian coast Steller sea lion abundance declined from a maximum of 115, to 15, individuals from 189 to 199; early decline likely influenced by harvests at some sites Changes in abundance occurred during all time periods but varied by site and period. Recent increases observed in Okhotsk region Southern extent of Steller sea lion distribution has moved north by some 5-9 km over the past 5 years

18 Northern Fur Seal Breeding Sites Russia North America Commander Islands Robben Island Pribilof Islands Bogoslof Island San Miguel Island Kuril Islands

19 Current worldwide population size ~1.1 million Commanders 2.6% Pribilofs 52.6% Kurils 1.2% Robben 11.5% Bogoslof 4.5% San Miguel.7%

20 NFS harvest on Pribilof Is., Males Killed (thousands) Commercial Harvest St. Paul St. George Juvenile males Females Killed (thousands) St. Paul St. George St. Paul (Commercial) St. George (Commercial) Year Females: ~32, Pelagic collections for science: >38, Year

21 Pribilof Islands pup production, St. Paul Production (1,s) St. Paul St. George : - 6.2% / yr St. George Production (1,s) Year

22 Bogoslof Island Pup Production Number of Pups % / yr Year

23 San Miguel Island (California) Pup Production Adams Cove Castle Rock Total Production Number of pups Year

24 NFS distribution in Russia Tuleny (Robben) Island Kuril Islands Commander Islands

25 Commander Islands: % year % year ALL rookeries pups born,

26 Tuleny pups born % year Kuril I. pups, % year

27 Summary of NFS trends Some past declines largely influenced by harvests Female harvest on the Pribilofs; ; may have affected other populations Recently: Declines in the Bering Sea Substantial increases at Tuleny, Kuril,, and Bogoslof Islands

28 Using pinniped population trends as indicators of ecosystem change Use of historical data complicated by: Gaps in time series Effects of harvests Current/future data promising. Needs: Assess influence of human activities on population trends (development, fishing, etc.) Consider other population characteristics Demographic: trends may be driven by changes in age structure (A. Kuzin; ; NFS at Tuleny I.) Behavioral: seasonal geographic distribution

29 Спасибо! Rolf Ream Vladimir Burkanov: