Sentinels of the Sea: Gray Whales Sentinels of the Sea: Gray Whales Respond to Climate ChangeRespond to Climate Change

Steven SwartzSteven SwartzNMFS Science & TechnologyNMFS Science & Technology

Normal back and post crainal region

Post Cranial DepressionPost Cranial Depression

Protruding ScapulaProtruding Scapula

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What is Going On?What is Going On?

Gray whale 101: who are they and Gray whale 101: who are they and why should we care?why should we care?

Climate change events in gray Climate change events in gray whales’ rangewhales’ range

Observed responses of gray whales to Observed responses of gray whales to changing environmental conditionschanging environmental conditions

What does the future hold for gray What does the future hold for gray whales?whales?

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

Evolution & Evolution & ClassificationClassification

Eschrichtius robustusEschrichtius robustus – modern gray whale – modern gray whale Family Family EschrichtiidaeEschrichtiidae – 50,000 – 120,000 YA – 50,000 – 120,000 YA Japan fossil from Late Pliocene – 1.8-3.5 MaJapan fossil from Late Pliocene – 1.8-3.5 Ma Italian fossil from Late Miocene – 7.5-11 MaItalian fossil from Late Miocene – 7.5-11 Ma

Relation to other CetaceansRelation to other Cetaceans

Mysticiceti – baleen (filter feeding – Mysticiceti – baleen (filter feeding – no teeth)no teeth) Balaenidae – right whalesBalaenidae – right whales Neo-Balaenidae – pigmy right whalesNeo-Balaenidae – pigmy right whales Balaenopteridae – rorquals (fin whales)Balaenopteridae – rorquals (fin whales) Eschrichtidae – unique bottom feeder Eschrichtidae – unique bottom feeder

(mostly)(mostly)

Historical DistributionHistorical Distribution

Mysticeti MigrationsMysticeti Migrations

Gray Whales Fall-Winter MigrationGray Whales Fall-Winter Migration

Guerrero NegroOjo De Liebre

San Ignacio

Bahia Magdalena

Baja Breeding LagoonsBaja Breeding Lagoons

Arctic Feeding GroundsArctic Feeding Grounds

Primary Bottom FeedingPrimary Bottom Feeding

Foraging flexibilityForaging 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 Climate Change Events in Gray Whales’ RangeGray Whales’ Range

Arctic oceanography – large scaleArctic oceanography – large scale Impact on primary production Impact on primary production Impact on benthic communities Impact on benthic communities Impact on gray whale food sourcesImpact on gray whale food sources

Climate-Ecosystem Climate-Ecosystem IssuesIssues

Loss of Arctic Sea Ice

Increasingly Acidic Oceans

CO2

pH

carbonate

1979

2005

Changes in Arctic Changes in Arctic CirculationCirculation

Bering Sea Ecosystem Bering Sea Ecosystem ShiftShift

“…“…warmer air temp…less seasonal sea warmer air temp…less seasonal sea ice…”ice…”

“…“…less water column & sediment carbon less water column & sediment carbon “…production…”“…production…”

“…“…loss of pelagic-benthic coupling of loss of pelagic-benthic coupling of organic production…”organic production…”

“…“…benthic invertebrate communities benthic invertebrate communities changing contemporaneous with shifts in changing contemporaneous with shifts in regional atmospheric and hydrographic regional atmospheric and hydrographic forcing…”forcing…”

“…reduction in benthic invertebrate prey and increases in pelagic fish…”

N. Pacific / Bering Sea Regime Shift N. Pacific / Bering Sea Regime Shift Decline in Infaunal Benthic PreyDecline in Infaunal Benthic Prey

J. Grebmeier’s Benthic Time SeriesJ. Grebmeier’s Benthic Time Series

Absence of Feeding GW in the Absence of Feeding GW in the

Chirikov Basin…Chirikov Basin…

Responses of Gray Whales Responses of Gray Whales to Changing Environmental to Changing Environmental

ConditionsConditions Population History – “Rise & Fall”Population History – “Rise & Fall” Feeding grounds shift from traditional Feeding grounds shift from traditional

areasareas Mortality events & population declineMortality events & population decline Changes in migration timingChanges in migration timing Lagoon use declinesLagoon use declines Reduction in calf production / calving Reduction in calf production / calving

intervalinterval Skinny whales / health indicesSkinny whales / health indices

ENP Gray Whale Population ENP Gray Whale Population HistoryHistory

8000

13000

18000

23000

28000

33000

1967

1969

1971

1973

1975

1977

1979

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

2001

2003

2005

2007

Census Year

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ENP Gray Whale Population Estimates-1967-2001Rugh et al. 2005

Removed fromESA List

Exceeded CarryingCapacity?

Why the decline?

Shorter Term Environment ChangesIn Breeding Range:

El Niño = Above normal temperature La Niña = Below normal temperature

Longer Term ArcticClimate Change & Ecosystem Change

1998

1999

Weak winds, weak upwellingWarmer water

Stronger winds,Increased upwellingCooler water

El Nino

Warm year:

Normal

Distribution and

Migration timing

La Nina

Cooler year:

Distribution shifts

South and into

Gulf of California

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

Range-Wide Stranded Range-Wide Stranded WhalesWhales

1994/19951994/1995 3939 1995/19961995/1996 2121 1996/19971996/1997 4646 1997/19981997/1998 5656 1998/19991998/1999 283283 (El Nino Event)(El Nino Event) 1999/20001999/2000 368 (La Nina event)368 (La Nina event) 2000/20012000/2001 2121 2001/20022001/2002 2626

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

Fewer Grays Utilizing Fewer Grays Utilizing LagoonsLagoons

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450

1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 65 69 73 77 81 85 89 93 97 101

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Low numbers of calves seen Low numbers of calves seen in the lagoons...in the lagoons...

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3 7 11 15 19 23 27 31 35 39 43 47 51 55 59 63 67 71 75 79 83 87 91 95 99

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Photographic Identification Calving interval increase:

1978-1982 – 2.1 years

1996-2006 – 2.4 years

Perryman’s Observations: little Perryman’s Observations: little sea ice = increased recruitmentsea ice = increased recruitment

2006/2007 Skinny 2006/2007 Skinny WhalesWhales

LSI-Photo-ID-Left-Sides: 11% skinnyLSI-Photo-ID-Left-Sides: 11% skinny LSI-Photo-ID-Right-sides: 13% skinnyLSI-Photo-ID-Right-sides: 13% skinny

SummarySummary Gray whale habitats are undergoing Gray whale habitats are undergoing

long-term and short-term long-term and short-term environmental changes affecting the environmental changes affecting the whales’ prey base.whales’ prey base.

Gray whales have expanded their Gray whales have expanded their foraging efforts spatially, temporally, foraging efforts spatially, temporally, and are utilizing alternative preyand are utilizing alternative prey

Gray whales have experienced Gray whales have experienced unusually high mortality events, lower unusually high mortality events, lower calf production, shifts in seasonal calf production, shifts in seasonal distribution and migrationdistribution and migration

Suggesting low body fat reserves & Suggesting low body fat reserves & generally insufficient energygenerally insufficient energy

Summary Continued…Summary Continued…

Apparent decrease in regular prey Apparent decrease in regular prey items resulting from increased items resulting from increased population predation and/or reduction population predation and/or reduction in primary production from climate in primary production from climate related eventsrelated events

Periodic compounded stress from local Periodic compounded stress from local climate events (e.g., El Nino / La Nina)climate events (e.g., El Nino / La Nina)

Gray whales expanding foraging Gray whales expanding foraging efforts in time and space – requires efforts in time and space – requires additional energyadditional energy

What will become of the gray whale??

““Consider this”Consider this”

Gray whales survived over the Gray whales survived over the millenniamillennia

Pleistocene glacial advances ended Pleistocene glacial advances ended 10-12,000 years ago10-12,000 years ago

Sea level was ~75 m lower than Sea level was ~75 m lower than presentpresent

Current major feeding areas were Current major feeding areas were above sea level and marine access to above sea level and marine access to Arctic blocked by Bering land bridgeArctic blocked by Bering land bridge

““robustus”robustus” for a reason for a reason

Grays are coastal species with a Grays are coastal species with a generalist and flexible feeding generalist and flexible feeding strategystrategy

Responsive to feeding opportunities Responsive to feeding opportunities throughout range and can vary throughout range and can vary foraging methods accordinglyforaging methods accordingly

Ability to use alternative prey, Ability to use alternative prey, feeding modes, and locations likely feeding modes, and locations likely contribute to their successcontribute to their success

Thank you