Sentinels of the Sea: Gray Whales Respond to Climate Change Steven Swartz

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 – 1.8-3.5 Ma • Italian fossil from Late Miocene – 7.5-11 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 PreyJ. 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. 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 Weak winds, weak upwelling Warmer water 1999 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: 1999-2000Follows El Nino / La Nina

29. Range-Wide Stranded Whales • 1994/1995 39 • 1995/1996 21 • 1996/1997 46 • 1997/1998 56 • 1998/1999 283 (El Nino Event) • 1999/2000 368 (La Nina event) • 2000/2001 21 • 2001/2002 26

30. In Laguna San Ignacio 1996: 3 calves 1997: 6 calves & 1 adult 1998: 3 calves 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: 1978-1982 – 2.1 years 1996-2006 – 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