1. Sentinels of the Sea: Gray Whales Respond to Climate Change
Steven Swartz
NMFS Science & Technology

3. Normal back and post crainal region

4. Post Cranial Depression

5. Protruding Scapula a b c

6. What is Going On? Gray whale 101: who are they and why should we care?
Climate change events in gray whales’ range
Observed responses of gray whales to changing environmental conditions
What does the future hold for gray whales?

7. Who are Gray whales ? Why should we care?

8. Evolution & Classification
Eschrichtius robustus – modern gray whale
Family Eschrichtiidae – 50,000 – 120,000 YA
Japan fossil from Late Pliocene – Ma
Italian fossil from Late Miocene – Ma

9. Relation to other Cetaceans
Mysticiceti – baleen (filter feeding – no teeth)
Balaenidae – right whales
Neo-Balaenidae – pigmy right whales
Balaenopteridae – rorquals (fin whales)
Eschrichtidae – unique bottom feeder (mostly)

10. Historical Distribution

11. Mysticeti Migrations

12. Gray Whales Fall-Winter Migration
Guerrero Negro
Ojo De Liebre
San Ignacio
Bahia Magdalena

13. Baja Breeding Lagoons

14. Arctic Feeding Grounds

15. Primary Bottom Feeding

16. Foraging flexibility Also skim, gulp and suck prey from water column
Can forage opportunistically in localized areas
Can utilize alternate swarming benthic invertebrates,
amphipods, isopods, mullusks, cumaceans,
shoaling mysids, shrimp, crabs, herring,
fish eggs and larvae

17. Climate Change Events in Gray Whales’ Range
Arctic oceanography – large scale
Impact on primary production
Impact on benthic communities
Impact on gray whale food sources

18. Climate-Ecosystem Issues
Increasingly Acidic Oceans
Loss of Arctic Sea Ice
1979 pH
carbonate
CO2
2005

19. Changes in Arctic Circulation

20. Bering Sea Ecosystem Shift
“…warmer air temp…less seasonal sea ice…”
“…less water column & sediment carbon “…production…”
“…loss of pelagic-benthic coupling of organic production…”
“…benthic invertebrate communities changing contemporaneous with shifts in regional atmospheric and hydrographic forcing…”
“…reduction in benthic invertebrate prey
and increases in pelagic fish…”

21. N. Pacific / Bering Sea Regime Shift Decline in Infaunal Benthic Prey J. Grebmeier’s Benthic Time Series

22. Absence of Feeding GW in the Chirikov Basin…

23. Responses of Gray Whales to Changing Environmental Conditions
Population History – “Rise & Fall”
Feeding grounds shift from traditional areas
Mortality events & population decline
Changes in migration timing
Lagoon use declines
Reduction in calf production / calving interval
Skinny whales / health indices

24. ENP Gray Whale Population History
Exceeded
Carrying
Capacity?
Removed from
ESA List
Why the decline?

25. Climate Change & Ecosystem Change
Longer Term Arctic
Climate Change & Ecosystem Change
Shorter Term Environment Changes
In Breeding Range:
El Niño = Above normal temperature
La Niña = Below normal temperature

26. 1998 1999 Weak winds, weak upwelling Warmer water Stronger winds,
Increased upwelling
Cooler water

27. La Nina
Cooler year:
Distribution shifts
South and into
Gulf of California
El Nino
Warm year:
Normal
Distribution and
Migration timing

28. Unusual Mortality: 1999-2000 Follows El Nino / La Nina

29. Range-Wide Stranded Whales
1994/
1995/
1996/
1997/
1998/ (El Nino Event)
1999/ (La Nina event)
2000/
2001/

30. In Laguna San Ignacio 1996: 3 calves 1997: 6 calves & 1 adult
1999: 2 calves & 3 adults
2000: 34 adults
Reduction in food = insufficient energy reserves = increased mortality

31. Fewer Grays Utilizing Lagoons

32. Low numbers of calves seen in the lagoons...
Photographic Identification
Calving interval increase:
– 2.1 years
– 2.4 years

33. Perryman’s Observations: little sea ice = increased recruitment

34. 2006/2007 Skinny Whales LSI-Photo-ID-Left-Sides: 11% skinny
LSI-Photo-ID-Right-sides: 13% skinny

35. Summary
Gray whale habitats are undergoing long-term and short-term environmental changes affecting the whales’ prey base.
Gray whales have expanded their foraging efforts spatially, temporally, and are utilizing alternative prey
Gray whales have experienced unusually high mortality events, lower calf production, shifts in seasonal distribution and migration
Suggesting low body fat reserves & generally insufficient energy

36. Summary Continued…
Apparent decrease in regular prey items resulting from increased population predation and/or reduction in primary production from climate related events
Periodic compounded stress from local climate events (e.g., El Nino / La Nina)
Gray whales expanding foraging efforts in time and space – requires additional energy

37. What will become of the gray whale??

38. “Consider this” Gray whales survived over the millennia
Pleistocene glacial advances ended 10-12,000 years ago
Sea level was ~75 m lower than present
Current major feeding areas were above sea level and marine access to Arctic blocked by Bering land bridge

39. “robustus” for a reason
Grays are coastal species with a generalist and flexible feeding strategy
Responsive to feeding opportunities throughout range and can vary foraging methods accordingly
Ability to use alternative prey, feeding modes, and locations likely contribute to their success

40. Thank you