Transcript Use of chemical profiles in assessing the feeding ecology of

Use of chemical profiles in
assessing the feeding ecology of
Alaska killer whales
Paul R. Wade | NOAA, National Marine Mammal Laboratory
Craig O. Matkin, Lance Barrett-Lennard – North Gulf Oceanic Society
Richard G. LeDuc - NOAA, Southwest Fisheries Science Center
John W. Durban, Marilyn E. Dahlheim, Nancy Black – NOAA, National Marine Mammal Laboratory
David P. Herman, Douglas G. Burrows, Margaret M. Krahn – NOAA, Northwest Fisheries Science Center
2005 summary:
14 Transient groups (19 biopsies)
22 Resident groups (15 biopsies)
Use of chemical profiles in assessing the feeding
ecology of eastern North Pacific killer whales
Krahn et al. submitted, Marine Environmental
Research
Qualitative comparison of “indicator” fatty
acids—fish and marine mammals
Relative proportions in fish
compared to marine mammals
Proportions (wt%) in biopsy blubber
for each killer whale ecotype
Fish
Marine mammals
Offshores
Residents
Transients
Fatty Acids
SCMU
C14:1n5
C16:1n7
L
L
H
H
1.4
19.6
3.5
21.4
4.2
27.1
Omega-3
C22:6n3
H
L
0.92
0.93
0.57
On-going analyses of fatty acids of potential marine mammal prey
Separation of killer whale ecotypes using
DFA of Fatty Acids in blubber
Separation of killer whale ecotypes using
DFA of PCBs in blubber
Carbon and nitrogen stable isotope
ratios of killer whales
1 Trophic
Level
offshore
onshore
Predicting the trophic level of killer
whale prey
20
Matkin & Saulitis diet:
50% gray whale
29% northern fur seal
14% minke whale
7% Steller sea lion
19
18
17
Steller
sea lion
15
 N
northern
fur seal
15
bowhead
whale
humpback
whale
minke
whale
13
12
11
10
9
EAI/T (n=26)
beluga
whale
16
14
harbor
seal
Pacfic
walrus
NMML/NOAA diet:
18% gray whale
45% northern fur seal Dall's
porpoise
9% minke whale
9% Steller sea lion
18% Dall’s porpoise
-21
-20
-19
harbor
porpoise
X
Calculated
EAI/T Prey
gray
whale
fin
whale
-18
13
 C
-17
-16
-15
Use of contaminant ratios to identify
regional sources
• California Signature: ∑DDTs/∑PCBs
– high ∑DDTS reflects heavy use of DDTs in California before
1970s ban
• Asian signature: ∑HCHs/∑PCBs & ∑chlordanes/∑PCBs
– high ∑HCHs or ∑chlordanes from pesticides used long after the
U.S. ban—ocean and air transport to Alaska
• Asian signature of “new” DDT: p,p’-DDT/∑DDTs
– high p,p’-DDT reflects recent pesticide use of DDTs in Asia or
Central America (low = “old” source in California)
• Alaska signature: low ∑DDTs/∑PCBs and high
∑chlordanes/∑PCBs
– Presence of Asian signature and absence of California signature
Ratio of DDT to PCB
Killer whales
Offshores (n=4)
Gulf of Alaska residents (n=17)
Eastern Aleutian Island residents (n=20)
Central Aleutian Island residents (n=3)
Eastern Aleutian Island transients (n=15)
West coast transients (California; n=4)
Possible prey
Chinook (California; n=29)
Chinook (Cook Inlet, Alaska; n=3)
California
signature
Steller sea lion pups (Alaska; n=4)
Harbor seal (Alaska; n=4)
Gray whale juveniles (North Pacific; n=17)
Northern fur seal (Alaska; n=16)
California sea lion (n=7)
0
2
4
DDTs/PCBs
6
8
Ratio of chlordanes/PCBs
Killer whales
Offshores (n=4)
Gulf of Alaska residents (n=17)
Eastern Aleutian Island residents (n=20)
Asian
signature
Central Aleutian Island residents (n=3)
Eastern Aleutian Island transients (n=15)
West coast transients (California; n=4)
Possible prey
Chinook (California; n=29)
Chinook (Cook Inlet, Alaska; n=3)
Steller sea lion pups (Alaska; n=4)
Harbor seal (Alaska; n=4)
Gray whale juveniles (North Pacific; n=17)
Northern fur seal (Alaska; n=16)
California sea lion (n=7)
0
0.2
0.4
0.6
0.8
 chlordanes/ PCBs
1
1.2
1.4
1.6
“New” DDT (from Asia)
High ratio = recent source
Killer whales
Offshores (n=4)
Gulf of Alaska residents (n=17)
Eastern Aleutian Island residents (n=20)
Central Aleutian Island residents (n=3)
Eastern Aleutian Island transients (n=15)
West coast transients (California; n=4)
Possible prey
Chinook (California; n=29)
Chinook (Cook Inlet, Alaska; n=3)
Steller sea lion pups (Alaska; n=4)
Harbor seal (Alaska; n=4)
Gray whale juveniles (North Pacific; n=17)
Northern fur seal (Alaska; n=16)
California sea lion (n=7)
0
0.02
0.04
0.06
0.08
p,p'-DDT/ DDTs
0.1
0.12
0.14
0.16
Concentration of PBDEs (flame retardant)
Eastern tropical Pacific
West Coast transients
12,600
Eastern Aleutian transients
Offshores
Gulf of Alaska Residents
Eastern Aleutians Residents
Central Aleutian Residents
0
1000
2000
3000
∑ PBDEs
4000
5000
Ratio of PBDEs to PCBs
Killer whales
Offshores (n=4)
Gulf of Alaska residents (n=17)
Eastern Aleutian Island residents (n=20)
Central Aleutian Island residents (n=3)
Eastern Aleutian Island transients (n=15)
West coast transients (California; n=10*)
Possible prey
Chinook (California; n=27)
Chinook (Cook Inlet, Alaska; n=0)
California
signature
Steller sea lion pups (Alaska; n=3)
Harbor seal (Alaska; n=0)
Gray whale juveniles (North Pacific; n=0)
Northern fur seal (Alaska; n=0)
California sea lion (n=7)
0.00
0.05
0.10
0.15
 PBDEs/ PCBs
0.20
0.25
0.30
Conclusions
•
Offshore killer whales consume a diet that is clearly
distinct from those of residents and transients
•
Offshore killer whales biopsied in Alaska feed at least
part of the year in California, presumably on highly
contaminated, high trophic level marine fish (not fur
seals as earlier hypothesized)
•
Resident and transient killer whales in Alaska have
contaminant ratios that appear to reflect the area
where they are sampled in spring/summer (e.g.,
suggests they do not make large scale movements in
fall/winter to other regions, unlike offshore whales)
Conclusions
•
–
•
Resident killer whales in Alaska exhibit a gradient in
chemical profiles from west (central Aleutians) to east
(Gulf of Alaska) that likely represents a shift from offshelf to continental shelf-based prey and lower to
higher trophic level.
This supports the hypothesis that diets of EAI/R and GOA/R
whales contain a high proportion of salmon, whereas the diet
of the CAI/R whales may include lower trophic level, demersal
prey.
Eastern Aleutian transients do not have a
spring/summer diet that is composed exclusively of
Steller sea lions, because stable isotope ratios show
that their diet must include lower trophic level species
to offset the high tropic level of the sea lions.
Acknowledgments
• Funding support
•
•
•
– North Pacific Research Board
– L. Jones of the NWFSC Marine Mammal Program
– T. K. Rowles of the Marine Mammal Health and Stranding
Response Program of NOAA Fisheries
Sample and data analysis
– D. W. Brown, G. M. Ylitalo, C. A. Sloan, R. H. Boyer, R. W. Pearce
and J. L. Bolton
Killer whale biopsy samples
– R. L. Pitman and the Southwest Fisheries Science Center
provided biopsy samples (Z38169, Z38170, Z38171 and Z38175)
– Nancy Black of the Monterey Bay Whale Watch provided samples
of the West Coast (California) killer whales
Killer whale prey data
– G. M. Ylitalo, S. O’Neill, J. West and J. Buzitis for Chinook salmon
– Kimberlee Beckmen for Steller sea lion