What Else is Eating Chinook and How Much are they Eating?

John FordPacific Biological Station

Fisheries and Oceans CanadaNanaimo, British Columbia

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

Killer whaleOrcinus orca

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

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

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.

Salmon sharkLamna ditropis

D. Perrine

Salmon shark are wide ranging, tend to move north in summer

D. Perrine

Source: Weng et al. 2008. MEPS

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

Harbour sealPhoca vitulina

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.

• 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.

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

• 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

California sea lionZalophus californianus

15

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

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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

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

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

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Steller sea lionEumetopias jubatus

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)

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.

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.

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.

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

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.

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