1. What Else is Eating Chinook and How Much are they Eating?
John Ford
Pacific Biological Station
Fisheries and Oceans Canada
Nanaimo, British Columbia

2. 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

3. Killer whale
Orcinus orca

4. 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

5. NRKW prey on many of the same stocks as SRKW
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
Percent
Month

6. Source: Riera, Ford & Chapman. in prep.
Significant overlap off southwestern Vancouver Island
Competition in important feeding area
Days with detections from Aug 2009 to Jul 2010: 80 SRKW, 54 NRKW
Days with detection
2009
2010
Source: Riera, Ford & Chapman. in prep.

7. Salmon shark
Lamna ditropis
D. Perrine

8. Salmon shark are wide ranging, tend to move north in summer
D. Perrine
Source: Weng et al MEPS

9. 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

10. Harbour seal
Phoca vitulina

11. Distribution: Harbour seal
Harbour seal haulout sites in British Columbia
DFO Population Assessment Pacific Harbour Seal (Phoca vitulina richardsi). DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2009/011.

12. Status: Harbour seal
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
Strait of Georgia
Current population abundance = in Strait of Georgia, 105,000 BC total. Abundance probably 10,000 seals when first surveys done in 1970, therefore increased by order of magnitude
DFO Population Assessment Pacific Harbour Seal (Phoca vitulina richardsi). DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2009/011.
Jeffries et al Trends and Status of Harbor Seals in Washington State: J. Wild. Manage.

13. Diet: Harbour seal
Average prey composition for harbour seals, Strait of Georgia
(n = 2,841 scat samples, collected )
Overall, salmonids represent about 4 % of prey. Note that scat studies done over 20 years ago and may not accurately reflect current predation patterns
Percent of overall diet
Olesiuk, P.F Annual prey consumption by harbor seals (Phoca vitulinaJ in the Strait of Georgia, British Columbia. Fish. Bull. 91:

14. Harbour seal: recent diet studies
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-Gutiérrez 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)

15. California sea lion
Zalophus californianus

16. 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

17. California sea lion abundance and distribution
Wintering haul out sites for California sea lions
Olesiuk, P.F Status of sea lions (Eumetopias jubatus and Zalophus californianus) wintering off southern Vancouver Island. Nat’l Marine Mammal Peer Review Committee Working Paper.

18. California sea lion abundance and distribution
Abundance of California sea lions,
Olesiuk, P.F Status of sea lions (Eumetopias jubatus and Zalophus californianus) wintering off southern Vancouver Island. Nat’l Marine Mammal Peer Review Committee Working Paper.

19. Diet: California sea lions in winter
Diet composition of sea lions wintering off southern Vancouver Island
Percent of overall diet
Olesiuk, P.F. and M.A. Bigg Seals and sea lions on the British Columbia coast. DFO/4101, Pacific Biological Station

20. Steller sea lion
Eumetopias jubatus

21. Status: Steller sea lion
Population depleted to 25-30% of historical abundance by control programs and harvests,
Abundance increasing at 3.5% per annum (5% in recent years)
Numbers in B.C. currently range from 32,000 in summer to 48,000 in winter
Olesiuk, P.F Abundance of Steller sea lions (Eumetopias jubatus) in British Columbia. Can. Science Advisory Sec., Fisheries and Oceans Canada, Ottawa. Res Doc 2011/000.

22. Status: Steller sea lion
Population depleted to 25-30% of historical abundance by control programs and harvests,
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
Historic Total Counts (1913)
Olesiuk, P.F Abundance of Steller sea lions (Eumetopias jubatus) in British Columbia. Can. Science Advisory Sec., Fisheries and Oceans Canada, Ottawa. Res Doc 2011/000.

23. Steller Sea Lion - Seasonal Distribution
Summer
Fall
Olesiuk, P., and J. Ford Hypothesis: Predation by marine mammals is an important contributor to the Fraser sockeye situation. Presentation to Sockeye Situation Working Group, Pacific Biological Station.

24. Steller Sea Lion - Seasonal Distribution
Winter
Spring
Olesiuk, P., and J. Ford Hypothesis: Predation by marine mammals is an important contributor to the Fraser sockeye situation. Presentation to Sockeye Situation Working Group, Pacific Biological Station.

25. 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 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 Hypothesis: Predation by marine mammals is an important contributor to the Fraser sockeye situation. Presentation to Sockeye Situation Working Group, Pacific Biological Station.

26. Seasonal Prevalence of Salmon
Olesiuk, P., and J. Ford 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 Trends in other Chinook salmon predators. Presentation to NOAA-DFO Killer Whale – Chinook Workshop 1, Sept 2011

27. Proportion of Salmon in Diet
Annual Salmon Consumption: 17,200 tonnes (CV ~ )
CV (~25-34%)
Olesiuk, P., and J. Ford Hypothesis: Predation by marine mammals is an important contributor to the Fraser sockeye situation. Presentation to Sockeye Situation Working Group, Pacific Biological Station.

28. Species of Salmon (DNA) (Preliminary results based on 1/3 of available samples analyzed to date)
Olesiuk, P., and J. Ford 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 Trends in other Chinook salmon predators. Presentation to NOAA-DFO Killer Whale – Chinook Workshop 1, Sept 2011

29. Species of salmon in Steller sea lion scat Summer:
Jeffries, S Trends in other Chinook salmon predators. Presentation to NOAA-DFO Killer Whale – Chinook Workshop 1, Sept 2011

30. Species of salmon in Steller sea lion scat Fall:
Jeffries, S Trends in other Chinook salmon predators. Presentation to NOAA-DFO Killer Whale – Chinook Workshop 1, Sept 2011

31. Species of salmon in Steller sea lion scat Winter:
Jeffries, S Trends in other Chinook salmon predators. Presentation to NOAA-DFO Killer Whale – Chinook Workshop 1, Sept 2011

32. Species of salmon in Steller sea lion scat Spring:
Jeffries, S Trends in other Chinook salmon predators. Presentation to NOAA-DFO Killer Whale – Chinook Workshop 1, Sept 2011

33. Conclusion: Steller sea lion
Opportunistic predators and consume all species of salmon and wide variety of other prey
Salmon a significant component of diet
Increasing abundance of sea lions likely associated with increasing predation rates on salmon