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

Normal back and post crainal region

Post Cranial Depression

Protruding Scapula a b c

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?

Who are Gray whales ? Why should we care?

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

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)

Historical Distribution

Mysticeti Migrations

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

Baja Breeding Lagoons

Arctic Feeding Grounds

Primary Bottom Feeding

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

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

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

Changes in Arctic Circulation

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…”

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

Absence of Feeding GW in the Chirikov Basin…

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

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

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

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

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

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

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

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

Fewer Grays Utilizing Lagoons

Low numbers of calves seen in the lagoons... Photographic Identification Calving interval increase: 1978-1982 – 2.1 years 1996-2006 – 2.4 years

Perryman’s Observations: little sea ice = increased recruitment

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

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

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

What will become of the gray whale??

“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

“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

Thank you