# Presentation: 035766

**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

**Loss of Arctic Sea Ice**

**Increasingly Acidic Oceans**

**CO****2**

**pH**

**carbonate**

- 1979

- 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

**Removed from**
**ESA List**

**Exceeded **
**Carrying**
**Capacity?**

**Why the decline?**

## Longer Term Arctic

- Shorter Term Environment Changes
- In Breeding Range:
- El Niño = Above normal temperature
- La Niña = Below normal temperature

**Longer Term Arctic**
**Climate Change & Ecosystem Change **

## 1998

- 1999

- Weak winds,
- weak upwelling
- Warmer water

- Stronger winds,
- Increased upwelling
- Cooler water

## El Nino

- Warm year:
- Normal
- Distribution and
- Migration timing

- La Nina
- Cooler year:
- Distribution shifts
- South and into
- Gulf of California

## Unusual Mortality: 1999-2000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
- 1998: 3 calves
- 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**