TrendsTrends inin abundanceabundance ofof StellerSteller seasea lionslions andand northernnorthern furfur sealsseals acrossacross thethe NorthNorth PacificPacific OceanOcean
Rolf R. Ream National Marine Mammal Laboratory, NMFS, Seattle, WA Vladimir Burkanov Natural Resources Consultants, Inc., Seattle, WA StellerSteller seasea lionlion andand northernnorthern furfur sealseal rangerange
Steller sea lion range Northern fur seal range Yellow dots = Steller sea lions Pink dots = Northern fur seals PribilofPribilof IslandIsland –– northernnorthern furfur sealseal atat--seasea distributiondistribution
WinterSummer Migration Breeding (November-June)(June-November) Steller Sea Lion Rookeries and Stock Structure
16 14 SE AK 12 s 10
and BC
s 8 ou
h 6 T 4 OR & CA 2 0 1970 1980 19 90 2000 Eastern Stock Non-Pup Steller Sea Lion Counts
80,000 70,000 Kenai-to-Kiska 60,000 Rookeries 50,000 Trend Rookeries and Haulouts 40,000 All Surveyed Sites 30,000 20,000 10,000 0 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 Non-Pup Steller Sea Lion Counts
2% 1991-2000 100% 2000-2004 0% 80% -2% 60% -4% 40% -6% 20% -8% 0% -10% -20% -12% -14% -40% -16% Aleutian Islands Gulf of Alaska -60% Aleutian Islands Gulf of Alaska Western Central Eastern Western Central Eastern Western Central Eastern Western Central Eastern Annual Rates of Change Mean ± 95% CI Historic Changes in Distribution and Abundance of Steller Sea Lions in the Western Pacific, 1700s–2002 Steller sea lion rookeries and houlouts along Asia coast, 1700s-2002 Steller sea lion rookeries and haulouts along Asia coast, 1700s-2002
Counts at 6 trend sites in the WBS, age 1+
6,000
5,000
4,000
3,000
2,000
1,000
0
1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 EK: ABUNDANCE & TRENDS, 1982-2002:
Counts at 8 trendt esisn iEK, 1983-2002 (age 1+)
2,500 +
2,1 000 e
1,g 500 a , r e
1,b 000 m 500 Nu
0
1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 CI: ABUNDANCE & TRENDS, 1930-2002:
Counts of SSL in Commander Islands, 1930-2002 (age 1+)
6,000
5,000
4,000
3,000
2,000
1,000
0 1930 1940 1950 1960 1970 1980 1990 2000 Historic Changes in Distribution and Abundance of Steller Sea Lions in the Western Pacific, 1700s–2002 SteKlleur rsiel aIs lionlands a bunda t rendnce insi Ktes:uril Is 1955-lands, 20011890-2001
25,0100,00 000 20,00080, 000
15,s 000
al 60, 000 u d
10,vi 000 i
d 40, 000 n 5,I 000 20,0 000
19550 1960 1965 1970 1975 1980 1985 1990 1995 2000 1880 1900 1920 1940 1960 1980 2000 Historic Changes in Distribution and Abundance of Steller Sea Lions in the Western Pacific, 1700s–2002 Historic Changes in Distribution and Abundance of Steller Sea Lions in the Western Pacific, 1700s–2002
TulenyTuleny I.I.
1400
1200
1000
800 pup
on- 600 N 400
200
0 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000
NON-PUP Historic Changes in Distribution and Abundance of Steller Sea Lions in the Western Pacific, 1700s–2002
THE NORTHERN PART OF THE SEA OF OKHOTSK: 1931-2002
8000 7000 6000 5000 4000 3000 2000 1000 0 1930 1940 1950 1960 1970 1980 1990 2000
Total abundance Reconstructed Steller sea lion abundance along Asian Reconstructed Steller sea lion abundance along Asian coast, coast, 1880-2000 1960-2000 120,000 30,000 100,000 25,000 20,00080,000 15,000 60,000 10,000 5,00040,000 20,0 000 1960s 1970s 1980s 1990s 2000s 0 1890s 1910s 1930s 1960s 1980s 2000s SummarySummary ofof SSLSSL alongalong thethe AsianAsian coastcoast
Steller sea lion abundance declined from a maximum of 115,000 to 15,000 individuals from 1890 to 1990; 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 500-900 km over the past 50 years NorthernNorthern FurFur SealSeal BreedingBreeding SitesSites
Russia North America
Commander Islands
Robben Island Pribilof Islands
San Miguel Island Bogoslof Island
Kuril Islands CurrentCurrent worldwideworldwide populationpopulation sizesize ~1.1~1.1 millionmillion
Pribilofs 52.6% Commanders 20.6%
Kurils 10.2% Bogoslof Robben 4.5% 11.5% San Miguel 0.7% NFSNFS harvestharvest onon PribilofPribilof Is.,Is., 19111911--19841984 Commercial Harvest 100 St. Paul 90
Juvenile males ) s 80 St. George d n
a 70 s u 60 o h t
( 50 d 40 lle i
K 30 s le 20 a
M 10 0 1910 1920 1930 1940 1950 1960 1970 1980
40 Year St. Paul 35 St. George
) Females: ~320,000 s St. Paul (Commercial) d
n 30 a St. George (Commercial) 25 hous 1956-1968 t (
d 20 lle i K
s 15 le a Pelagic collections for m 10 Fe 5 science: >38,000
0 1915 1930 1945 1960 1975 1958-1974 Year PribilofPribilof IslandsIslands puppup production,production, 19121912--20042004 500 100
450 90
400 80 000s) , 000s) 1
, St. Paul ( 1 350 70 n ( o n i t o 300 St. George 60 i c t u c 1998-2004: d u 250 50 o d - 6.2% / yr r o r
200 40 P e P l g r u 150 30 a o e P . G t 100 20 . t S 50 10 S 0 0 1900 1920 1940 1960 1980 2000 2020 Year BogoslofBogoslof IslandIsland PupPup ProductionProduction
14000
12000
10000 ups
P 8000 of r e b 6000 m u N 4000 1997 - 2005 +12% / yr 2000
0 1980 1985 1990 1995 2000 2005 Year SanSan MiguelMiguel IslandIsland (California)(California) PupPup ProductionProduction
3500 Adams Cove 3000 Castle Rock Total Production 2500 s
pup 2000 of r e b
m 1500 u N 1000
500
0 1970 1975 1980 1985 1990 1995 2000 2005 Year NFS distribution in Russia
Commander Islands Tuleny (Robben) Island Kuril Islands CommanderCommander Islands:Islands: 1958-2004 +0.5 % year 1995-2004 - 2.1 % year
ALL rookeries pups born, 1958-2004
80000 70000 60000 50000 40000 30000 20000 10000 0 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003 Tuleny pups born 1995-2004 + 7.8 % year 60000 50000 40000 30000 20000 10000 0 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003
Kuril I. pups, 1958-2005 1988-2005 + 4.4 % year 30000
25000
20000
15000
10000
5000
0 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003 SummarySummary ofof NFSNFS trendstrends z SomeSome pastpast declinesdeclines largelylargely influencedinfluenced byby harvestsharvests z FemaleFemale harvestharvest onon thethe PribilofsPribilofs;; maymay havehave affectedaffected otherother populationspopulations z Recently:Recently: z DeclinesDeclines inin thethe BeringBering SeaSea z SubstantialSubstantial increasesincreases atat TulenTulenyy,, KurilKuril,, andand BogoslofBogoslof IslandsIslands UsingUsing pinnipedpinniped populationpopulation trendstrends asas indicatorsindicators ofof ecosystemecosystem changechange z UseUse ofof historicalhistorical datadata complicatedcomplicated by:by: z GapsGaps inin timetime seriesseries z EffectsEffects ofof harvestsharvests z Current/futureCurrent/future datadata promising.promising. Needs:Needs: z AssessAssess influenceinfluence ofof humanhuman activitiesactivities onon populationpopulation trendstrends (development,(development, fishing,fishing, etc.)etc.) z ConsiderConsider otherother populationpopulation characteristicscharacteristics z Demographic: trends may be driven by changes in age structure (A. Kuzin; NFS at Tuleny I.) z Behavioral: seasonal geographic distribution СпасибоСпасибо!!
E-mail: Rolf Ream [email protected] Vladimir Burkanov: [email protected]