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What Else is Eating Chinook and How Much are they Eating?
John FordPacific Biological Station
Fisheries and Oceans CanadaNanaimo, British Columbia
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Competition for SRKW Chinook by other predators
• Only concerned with 3–6 yr old Chinook• Potential competitors:
» Other killer whale populations» Salmon shark» Harbour seal» California sea lion» Steller sea lion
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Killer whaleOrcinus orca
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NRKW and SRKW mostly allopatric in summer and fall, extent of overlap in winter/spring unknown
Northern(n = 4,765 encounters)
Southern(n = 12,956 encounters)
Sources: Ford 2006 CSAS Res Doc 2006/072; Whale Museum, Friday Hbr; L. Barre, NOAA
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PercentP
erce
nt
Month
Locations of sampling, stock regions, and monthly distribution of Chinook salmon sampled from feeding events by northern resident killer whales in the northern Queen Charlotte Islands (PFMA 1). n = 33
NRKW prey on many of the same stocks as SRKW
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Significant overlap off southwestern Vancouver Island
• Competition in important feeding area
• Days with detections from Aug 2009 to Jul 2010: 80 SRKW, 54 NRKW
Day
s w
ith d
etec
tion
2009 2010
Source: Riera, Ford & Chapman. in prep.
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Salmon sharkLamna ditropis
D. Perrine
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Salmon shark are wide ranging, tend to move north in summer
D. Perrine
Source: Weng et al. 2008. MEPS
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Salmon shark
• Feeds on a wide variety of fishes and squids• Salmon is preferred prey during summer months in
coastal waters• Sockeye comprises majority of prey in NE Pacific;
Chinook predation appears minor• Abundance and trend poorly known• Some anecdotal evidence that abundance may be
increasing, but overall probably lower than 50 years ago
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Harbour sealPhoca vitulina
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Harbour seal haulout sites in British Columbia
Distribution: Harbour seal
DFO. 2010. Population Assessment Pacific Harbour Seal (Phoca vitulina richardsi). DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2009/011.
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• Population severely depleted by control programs and harvest, ended in 1970• Abundance increased 10-fold since early 1970s• Increased at 11.5% per year before stabilizing in 1990s• Current abundance: ca. 40,000 Strait of Georgia, 32,000 Washington
DFO. 2010. Population Assessment Pacific Harbour Seal (Phoca vitulina richardsi). DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2009/011.
Status: Harbour seal
Strait of Georgia
Jeffries et al. 2003. Trends and Status of Harbor Seals in Washington State: 1978-1999. J. Wild. Manage.
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0 10 20 30 40 50
Unidentified/other fish
Smelts, mainly eulachon
Pacific cod
Pacific sand lance
Walleye pollack
Pacific tomcod
Rockfishes
Flatfishes
Sculpins
Flatfishes
Cephalopods
Surfperches
Lingcod
Plainfin midshipman
Pacific salmon
Pacific herring
Pacific hake
Percent of overall diet
Average prey composition for harbour seals, Strait of Georgia(n = 2,841 scat samples, collected 1982-88)
Olesiuk, P.F. 1993. Annual prey consumption by harbor seals (Phoca vitulinaJ in the Strait of Georgia, British Columbia. Fish. Bull. 91:491-515.
Diet: Harbour seal
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• Recent scat studies by WDFW in San Juans show adult salmon in 58% of scats in summer/fall, 11% in winter, and 4% in spring
• Of 76 salmon ID’d from otoliths, 7 (9%) were Chinook
• Scat studies in 2011 by Austen Thomas, UBC, in Fraser River estuary and western Strait of Georgia show diets dominated by pink salmon, no Chinook detected.
• Acevedo-Gutierrez et al.’s recent studies (document on ESSA website) suggest harbour seal diet in San Juan Islands may be composed of 3-17% Chinook salmon; whales may take (1030 ± 223) tonnes of adult Chinook (based on estimate from fatty acid signatures)
Harbour seal: recent diet studies
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California sea lionZalophus californianus
15
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Status: California sea lion
• Abundance increased from 50,000 in 1975 to 297,000 in 2010• Males migrate to Washington, southern coast of Vancouver Island
and the Strait of Georgia during winter• Wintering animals started appearing in BC during 1960s, peaked at
4500 in 1984, declined to 1500 by 2004
16
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California sea lion abundance and distribution
Wintering haul out sites for California sea lions
Olesiuk, P.F. 2004. Status of sea lions (Eumetopias jubatus and Zalophus californianus) wintering off southern Vancouver Island. Nat’l Marine Mammal Peer Review Committee Working Paper. 17
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California sea lion abundance and distribution
Abundance of California sea lions, 1984-85
Olesiuk, P.F. 2004. Status of sea lions (Eumetopias jubatus and Zalophus californianus) wintering off southern Vancouver Island. Nat’l Marine Mammal Peer Review Committee Working Paper. 18
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Diet composition of sea lions wintering off southern Vancouver Island
Olesiuk, P.F. and M.A. Bigg. 1988. Seals and sea lions on the British Columbia coast. DFO/4101, Pacific Biological Station
0 5 10 15 20 25 30 35 40
Other Fish
Lingcod
Skate
Sandlance
Eulachon
Squid/Octopus
Salmon
Dogfish
Hake/Pollock
Herring
Percent of overall diet
Diet: California sea lions in winter
19
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Steller sea lionEumetopias jubatus
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Year
1960 1970 1980 1990 2000 2010
Num
ber
Cou
nted
0
5000
10000
15000
20000
25000
30000
35000
Total CountPup Count
• Population depleted to 25-30% of historical abundance by control programs and harvests, 1912-1967
• Abundance increasing at 3.5% per annum (5% in recent years); eastern stock now about 53,000
• Numbers in B.C. currently range from 32,000 in summer to 48,000 in winter
Olesiuk, P.F. 2011. Abundance of Steller sea lions (Eumetopias jubatus) in British Columbia. Can. Science Advisory Sec., Fisheries and Oceans Canada, Ottawa. Res Doc 2011/000.
Status: Steller sea lion
Historic Total Counts (1913)
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122°W
122°W
124°W
124°W
126°W
126°W
128°W
128°W
130°W
130°W
50°N 50°N
48°N 48°N
46°N 46°N
0 50 100 150 200
Kilometers
122°W
122°W
124°W
124°W
126°W
126°W
128°W
128°W
130°W
130°W
50°N 50°N
48°N 48°N
46°N 46°N
0 50 100 150 200
Kilometers
Steller Sea Lion - Seasonal Distribution
Summer Fall
Olesiuk, P., and J. Ford. 2011. Hypothesis: Predation by marine mammals is an important contributor to the Fraser sockeye situation. Presentation to Sockeye Situation Working Group, Pacific Biological Station.
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Steller Sea Lion - Seasonal Distribution
122°W
122°W
124°W
124°W
126°W
126°W
128°W
128°W
130°W
130°W
50°N 50°N
48°N 48°N
46°N 46°N
0 50 100 150 200
Kilometers
122°W
122°W
124°W
124°W
126°W
126°W
128°W
128°W
130°W
130°W
50°N 50°N
48°N 48°N
46°N 46°N
0 50 100 150 200
Kilometers
Winter Spring
Olesiuk, P., and J. Ford. 2011. Hypothesis: Predation by marine mammals is an important contributor to the Fraser sockeye situation. Presentation to Sockeye Situation Working Group, Pacific Biological Station.
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Steller Sea Lion - Daily Prey Requirements estimated by P. Olesiuk, DFO
• Young-of-year: 4 kg to 15 kg by first spring (17-23% body mass)• Adult females: 15 kg (16 kg pregnant; perhaps up to 30 kg while
lactating) (5.3% body mass)• Adult males: 28 kg (15 kg summer to 33-34 kg outside breeding
season) (4.1% of body mass)• Overall per capita: 18 kg• Annual Consumption: 161,000 tonnes (CV ~22-25%)
Olesiuk, P., and J. Ford. 2011. Hypothesis: Predation by marine mammals is an important contributor to the Fraser sockeye situation. Presentation to Sockeye Situation Working Group, Pacific Biological Station.
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Seasonal Prevalence of Salmon
0%
10%
20%
30%
40%
50%
Summer Fall Winter Spring
Pre
vale
nce
of
Sa
lmo
n (
% o
f S
am
ple
s) . Adult Salmon
Juvenile Salmon
Olesiuk, P., and J. Ford. 2011. Hypothesis: Predation by marine mammals is an important contributor to the Fraser sockeye situation. Presentation to Sockeye Situation Working Group, Pacific Biological Station.Jeffries, S. 2011. Trends in other Chinook salmon predators. Presentation to NOAA-DFO Killer Whale – Chinook Workshop 1, Sept 2011
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Proportion of Salmon in Diet
0%
5%
10%
15%
20%
25%
Summer Fall Winter Spring
Season
Pe
rce
nt
of
Sa
lmo
n in
Die
t
Annual Salmon Consumption: 17,200 tonnes (CV ~ 0.35-0.40)
Olesiuk, P., and J. Ford. 2011. Hypothesis: Predation by marine mammals is an important contributor to the Fraser sockeye situation. Presentation to Sockeye Situation Working Group, Pacific Biological Station.
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Species of Salmon (DNA)(Preliminary results based on 1/3 of available samples analyzed to date)
Olesiuk, P., and J. Ford. 2011. Hypothesis: Predation by marine mammals is an important contributor to the Fraser sockeye situation. Presentation to Sockeye Situation Working Group, Pacific Biological Station.Jeffries, S. 2011. Trends in other Chinook salmon predators. Presentation to NOAA-DFO Killer Whale – Chinook Workshop 1, Sept 2011