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On Foraging Models and Lower Columbia Subsistence Change

On Foraging Models and Lower Columbia Subsistence Change. Virginia L. Butler Dept. Anthropology Portland State University. Acknowledgements Many people in this session have helped out in many ways over the last 10 years; funding for analysis: USFWS, AINW, CASCADIA

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On Foraging Models and Lower Columbia Subsistence Change

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  1. On Foraging Models and Lower Columbia Subsistence Change Virginia L. Butler Dept. Anthropology Portland State University

  2. 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

  3. 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

  4. High Rank Population Low Collapse Time Predicted Prey Response to Changing Human Population Size and Predation Pressure

  5. 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

  6. Based on Body Size Criteria High Ranked Fishes -- Sturgeon (Acipenser sp ) based on body size criteria Salmonidae (Orcorhynchus sp.) Fishbase

  7. Low Ranked Fishes Eulachon (Thaleichthys pacificus) Minnows & Suckers Cyprinidae Catostomidae Stickleback (Gasterosteus aculeatus) Fishbase

  8. European Contact Multnomah 3 Multnomah 2 Multnomah 1 Merrybell Plot of Fish Index by Site and Age NISP Large Fish/All Fish Culture Unit TIME

  9. 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

  10. “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?

  11. Portland Basin Butler [1 mm mesh] Cathlapotle (CL1) Saleeby [6.4 mm mesh]

  12. “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

  13. Cathlapotle 1 x 1 meter unit; NISP = 2693 N=228 N=954 * *100th of volume that was screened through larger mesh

  14. 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

  15. Cathlapotle Variation in Fish Family Frequency by Bulk Sample NISP = 2392 > 2 mm Samples from pre & post Euro-contact Post Pre Post Salm Sturg Minnow-Sucker Eulachon Stickleb

  16. 1888 USCGS Recent Projects Columbia Slough- Smith-Bybee Lakes

  17. Fish Remains Analysed-- Fieldwork Directed by Ellis (AINW), Pettigrew (Cascadia)

  18. Columbia Slough Sites > 1 mm > 3.2 mm No Post-Contact Component AD 200- 1250 600 BC AD 200 AD 1250- 1750

  19. Implications? • Low ranked fishes important -- pre-contact period • But …are minnow/suckers LOW RANKED (relative to ALL FISH) in backwater setting? • - Initial model—environment treated as ONE homogenous patch; all resources equally accessible. Is this reasonable?

  20. Lower Columbia River & Floodplain minnow, suckers sturgeon floodplain migratory eulachon salmonids Columbia R. main stem minnows & suckers sturgeon

  21. 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

  22. weirs on 2nd or 3rd order streams The Cascades Willamette Falls Pettigrew 1990 basemap

  23. 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

  24. AD 1750- 1835 AD 200- 1250 AD 1250- 1750 600 BC AD 200 Plot of Backwater Fish Index by Site and Age C0 5 NISP Sturgeon/Sturgeon & Min-Sucker CL 1

  25. AD 1750- 1835 AD 200- 1250 AD 1250- 1750 600 BC AD 200 Plot of Backwater Vertebrate Index by Site and Age CL 1 NISP Mammal/Mammal & Min-Sucker C0 5

  26. Conclusions • Foraging Models – extremely successful in accounting for resource selection and subsistence change around world. • Models provide framework for hypotheses—highlights 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 we’re making progress…

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