On Foraging Models and

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On Foraging Models and Lower Columbia
Subsistence Change
Virginia L. Butler Dept. Anthropology Portland
State University
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• Acknowledgements
• Many people in this session have helped out in
  many ways over the last 10 years funding for
  analysis USFWS, AINW, CASCADIA
• Student help Greg Baker, Stephanie Butler, Mike
  Mayhew, Lee Levy, Roy Schroeder, Martha Corcoran,
  Fred Anderson

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Previous Work

• Examined 2000 yr old archaeo-faunal record in
  Portland Basin (Butler 2000 using Saleeby 1983,
  and newer records)
• Tested against expectations from foraging theory
  
• Assigned fauna to rank
• HIGH vs. LOW
• salmon minnow/sucker
• sturgeon eulachon
• mammals stickleback

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Predicted Prey Response to Changing Human
Population Size and Predation Pressure
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Abundance Indices (AIs)
NISP High Ranked Taxa NISP High Low Ranked Taxa
- Ratios range 1 0 higher the ratio,
greater the contribution of high ranked prey -
Body Size proxy measure for rank, larger the
body, higher the rank
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Based on Body Size Criteria
High Ranked Fishes --
Sturgeon (Acipenser sp )
based on body size criteria
Salmonidae (Orcorhynchus sp.)
Fishbase
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Low Ranked Fishes
Eulachon (Thaleichthys pacificus)
Minnows Suckers
Cyprinidae
Catostomidae
Stickleback (Gasterosteus aculeatus)
Fishbase
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Plot of Fish Index by Site and Age
NISP Large Fish/All Fish
Culture Unit
TIME
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Implications? 1- Population density high enough
and predation pressure great enough to depress
animal populations 2- Historic-ethnographic
records that emphasize salmon an artifact of
reduced Native American population size and
predation pressure. 3- BUT results tentative
for a variety of reasons
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• More Work Needed
• Sampling concerns most faunal remains recovered
  from coarse-mesh screens (masking potential
  variation in tiny fish)
• Taphonomic concerns (is stickleback cultural?
  Variation in preservation conditions?)
• More faunal collections needed (esp. early
  sites)
• Explanation for the change (if in fact patterns
  are real)
• Is it human-caused resource depression?
• Or per capita decline in high ranked resources?
• - What about alternate approaches to resource
  ranking or patch definition?

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Portland Basin
Butler 1 mm mesh
Cathlapotle (CL1)
Saleeby
6.4 mm mesh
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Tiny Fish Representation

• Eulachon (max length 300 mm)
• - Stickleback (max length 89 mm)
• - Only trace amounts of fish recovered from sites
  screened with 6.4 or 3.2 mm mesh
• Where 1 or 2 mm mesh used, remains found often
  in high abundance

Fishbase
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Cathlapotle 1 x 1 meter unit NISP 2693
N228
N954

100th of volume that was screened through larger
mesh

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Cathlapotle 10-15 liter bulk samples, water
screen 4, 2, 1, .5 mm To Date Analysed 12
samples 4, 2 mm 1 sample -- 1 mm
MNI 430!
Stickleback
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Cathlapotle
Variation in Fish Family Frequency by Bulk Sample
NISP 2392 gt 2 mm
Samples from pre post Euro-contact
Post
Pre
Post
Salm
Sturg
Minnow-Sucker
Eulachon
Stickleb
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1888 USCGS
Recent Projects Columbia Slough- Smith-Bybee Lakes
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Fish Remains Analysed--
Fieldwork Directed by Ellis (AINW), Pettigrew
(Cascadia)
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Columbia Slough Sites
gt 1 mm
gt 3.2 mm
No Post-Contact Component
AD 200- 1250
AD 1250- 1750
600 BC AD 200
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• Implications?
• Low ranked fishes important -- pre-contact
  period
• But are minnow/suckers LOW RANKED (relative to
  ALL FISH) in backwater setting?
• - Initial modelenvironment treated as ONE
  homogenous patch all resources equally
  accessible. Is this reasonable?

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Lower Columbia River Floodplain
minnow, suckers sturgeon
floodplain
migratory eulachon salmonids
Columbia R. main stem
minnows suckers sturgeon
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1888 Map showing extensive backwater sloughs
Recent catch records Biomass of resident FW fish
in sloughs 10 times greater than biomass of all
fish in main channel
K. Ames
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weirs on 2nd or 3rd order streams
The Cascades
Willamette Falls
Pettigrew 1990 basemap
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Treat Backwater Slough as Separate Patch
new abundance indices
-- Backwater Fish NISP Sturgeon NISP
Sturgeon Minnow-Sucker
-- Floodplain Vertebrate NISP
Mammals NISP Mammals Minnow-Sucker
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Plot of Backwater Fish Index by Site and Age
C0 5
NISP Sturgeon/Sturgeon Min-Sucker
CL 1
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Plot of Backwater Vertebrate Index by Site and Age
CL 1
NISP Mammal/Mammal Min-Sucker
C0 5
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• Conclusions
• Foraging Models extremely successful in
  accounting for resource selection and subsistence
  change around world.
• Models provide framework for hypotheseshighlight
  s the data essential for testing
• Still working on the appropriate scales of
  analysis comparator taxa for A.I. and patch
  definitions
• - more work needed (sampling, tapho)and
  samples from 2000 yr old components in this
  YOUNG ENVIRONMENT
• - But were making progress

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