Environmental Variability, Bowhead Whale Distributions, and Iupiat Subsistence Whaling Preliminary R

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Environmental Variability, Bowhead Whale
Distributions, and Iñupiat Subsistence Whaling
Preliminary Results of a 2005 Late Summer Field
Program
C. J. Ashjian, P. Alatalo, R. G. Campbell, J. C.
George, A. Hartz, J. Manker, S. E. Moore, S. R.
Okkonen, B. F. Sherr, E. B. Sherr
Funded by the National Science Foundation as part
of the Study of the Northern Alaska Coastal
System (SNACS)
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Bowhead whales are found on the shelf near
communities such as Barrow along northern Alaska
during their fall migration and are hunted there

• Why do whales prefer certain locations along the
  shelf?
• How might climate variability affect this
  behavior?
• How might climate variability affect whaling
  success?

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Hypothesis 1 Bowhead whale distribution is
influenced by variability in plankton
concentration that is linked to physical and
biological oceanography and the AO phase

• Bowhead whales congregate at Barrow in fall
  because of dense zooplankton patches that form
  there at physical features (eddies, fronts,
  convergences)
• The two AO climate regimes result in different
  physical oceanographic conditions (PW input,
  currents, water column structure, fronts) that
  will impact the formation and composition
  (euphasiids vs. copepods) of whale prey
  aggregations.

Hypothesis 2 Climate-induced changes in the
variability of bowhead whaling conditions (whale
availability, weather) will strain the adaptive
capacity of Iñupiat whale hunters
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Our system and approach
Social factors
Local weather conditions
Pan-Arctic climate
Whale migration
Hunting effort and success
Ice ocean conditions
Zooplankton
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Field component of a multidisciplinary,
multi-investigator project

• Oceanographers
• Carin Ashjian (WHOI)
• Robert Campbell (URI)
• Steve Okkonen (UAF)
• Barry Sherr (OSU)
• Ev Sherr (OSU)

• Modelers
• Wieslaw Maslowski (NPS)
• Yvette Spitz (OSU)

• Social Scientists
• Steve Braund (SRBA)
• Jack Kruse (UMassAmherst)
• Craig Nicolson (UMassAmherst)

• Whale Ecologists
• Craig George (NSBWM)
• Sue Moore (APL NOAA)

Goal of field component Demonstrate existence of
prey patches at fronts and provide input and
verification for biological-physical modeling and
social science efforts
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Summer 2005 Oceanographic Sampling

• The R/V Annika Marie, anchored in Elson Lagoon
  (43)
• Sampling Season August 18 - September 13
• Boat Field team Carin Ashjian, Bob Campbell,
  Steve Okkonen, Barry Sherr, Ev Sherr, Phil
  Alatalo, Aaron Hartz, Jeff Manker (teacher from
  Gilroy, CA) and captains Bill Kopplin and Ned
  Manning

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Instruments and Measurements

• CTD and Rosette - Temperature, salinity,
  pressure, fluorescence, water for chlorophyll,
  nutrient, and microzooplankton determinations
• ADCP - Velocity, backscatter (failed during
  cruise)
• ACROBAT - Temperature, salinity, pressure,
  fluorescence, C-DOM, optical backscatter
• Plankton nets (150 and 53 µm)
• Video Plankton Recorder
• Marine mammal and bird sightings

Acrobat
Deploying Acrobat
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Sampling Locations

• Along 7 lines or transects that extended from
  nearshore out to about 150 meters of water depth
• Sampling was often weather limited
• Each long line took about 28 hours round trip
• Surveyed on the outbound trip using Acrobat (blue
  lines) directed sampling based on plots of
  hydrography, fluorescence, and optical
  backscatter on the return trip using CTD, nets,
  and VPR (red dots)

Barrow Canyon
Barrow
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Salinity
Temperature

• Colder, fresh water over shelf - ice melt?
• Warmer water just over shelf break - from Barrow
  Canyon?
• Cold, saltier water below - Bering Sea Winter
  Water
• Pycnocline extending off shelf
• Note inshore front in both salinity and
  temperature

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Organic Material
Particles
Fluorescence

• All three are very high inshore
• Very low particles and chlorophyll in the ice
  melt water
• Elevated subsurface fluorescence extending
  offshore at shelf break, in association with
  hydrographic front
• Front between nearshore and offshore water
• Dissolved organic material decreases away from
  land

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Fluorescence with lt 10µm Chlorophyll from
bottles
Surface

• Distinct subsurface peak associated with
  temperature structure seen extending offshore
  from shelf break
• Elevated chlorophyll also inshore
• Higher proportion of chlorophyll as small cells
  (lt 10 µm) over shelf and offshore, especially in
  subsurface peak, with higher proportion of large
  cells inshore

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Microzooplankton (Ciliates and Dinoflagellates)
Microzooplankton Carbon (µg C L-1)
Phytoplankton and Microzooplankon Carbon

• High abundances, as carbon, of microzooplankton
  especially in surface water offshore abundances
  decrease with depth
• Where microzooplankton were abundant, they were
  close to equivalent to phytoplankton in terms of
  carbon
• This indicates a late season, heterotrophic food
  web

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Acoustic Backscatter from the ADCP

• Elevated backscatter inshore likely resulted from
  scattering off of the suspended particles (sand,
  silt)
• High backscatter at the shelf break associated
  with temperature and fluorescence features

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Zooplankton Composition/Abundance (150 µm)
1164 m-3
1226 m-3

• Although abundance was similar, composition very
  different
• Many more large calanoids inshore of shelf break
• We missed the high backscatter with the net but
  it may have resulted in part from barnacle nauplii

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How do these properties vary across the shelf?
Temperature at 7 m
Salinity at 7 m

• Very warm Pacific Water to the west in Barrow
  Canyon
• Front between cold water inshore (ice melt?) and
  warmer water offshore
• Suggestion of filament or eddy formation

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How do these properties vary across the shelf?
Temperature at 7 m
Chlorophyll fluorescence at 7 m

• Elevated fluorescence in Barrow Canyon, in warmer
  water offshore, and along Elson Lagoon inlets

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Chlorophyll from 0-10 m from Nisken Bottles
lt10 µm Chlorophyll ()
Total Chlorophyll (mg m-3)

• Highest total chlorophyll in and near Barrow
  Canyon and between barrier islands along Elson
  Lagoon
• Fairly high proportion of small cells at most
  locations, suggesting late summer, regenerative
  nutrient based community
• Highest proportion of larger cells at Elson
  Lagoon barrier islands

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How do these properties vary across the shelf?
Optical Backscatter at 7 m
CDOM at 7 m

• Very high particle load and dissolved organic
  material on shelf near entrances to Elson Lagoon

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This is what these boundaries look like from a
plane..
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Bird Observations (Daylight Only!)
Contours of temperature

• Most birds seen in frontal areas and along Barrow
  Canyon

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Aerial Surveys to Find Bowhead Whales
Craig George

• Sue Moore, Craig George, and others flew surveys
  with this plane to find the location of marine
  mammals, especially bowhead whales
• From the plane, the locations can be noted
  relative to oceanic fronts, the shoreline, and
  the ice edge

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Whale Observations from September 8 Aerial Survey

• Two aggregations of bowhead whales seen One to
  the NE near the edge of Barrow Canyon and one
  near the inlets into Elson Lagoon
• Whale aggregation seemed to be in the region of
  elevated sediment/OM/chl
• We had seen no bowhead whales before this day and
  we dont know where they came from!

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Preliminary Conclusions

• Multiple hydrographic zones and structures were
  observed across the study area associated with
  biological distributions including upper trophic
  level birds/animals
• The nearshore zone, with high suspended sediment
  load, organic material, and chlorophyll appears
  to be a congregation area for bowhead whales,
  despite appearing to be quite inhospitable
• The shelf contained a late summer, regenerative
  nutrient based ecosystem with surprisingly high
  abundances of microzooplankton
• We did not conclusively observe patches of whale
  prey, although the samples and data are not
  completely analyzed
• We plan to focus more intensively on the sediment
  laden nearshore next year, although our remote
  sensing techniques for zooplankton will not work
  there and we will need to use the more
  traditional nets

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Acknowledgements

• Bill Kopplin and Ned Manning, the captains of the
  R/V Annika Marie, for their valuable inputs to
  our program
• The Barrow Whaling Captains Association, the
  Alaska Eskimo Whaling Commission, the North Slope
  Borough, and the community of Barrow for their
  support
• Glenn Sheehan, Henry Gueco, Robert Bulger and the
  Barrow Arctic Science Consortium Staff for
  logistic support in Barrow
• VECO Polar Services for logistic support in
  Deadhorse / Prudhoe Bay
• Bill Streever and Wilson Cullers at British
  Petroleum for assistance in accessing West Dock
  in Prudhoe Bay to load the Annika Marie
• The ARMADA Program at the University of Rhode
  Island for the participation of Jeff Manker (high
  school teacher)

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Two Nutrients from Bottles at 10 m
Silicate
Phosphate

• Elevated phosphate and silicate (and NH4) over
  shelf indicates regenerative community
• High silicate also typical of Pacific Water that
  may be upwelling along edge of Barrow Canyon

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September 8 Observations - Close Up

• White tracks are plane tracks purple lines are
  our ocean sampling lines black dots are whale
  locations
• This group of whales is found in the very turbid
  water near the inshore ends of our transects