Pacific salmon has been a staple resource for residents of British Columbia for over
seven thousand years. Archaeological evidence obtained from a shell midden at Namu,
B.C., provides detailed information about the diets of the First Peoples living at Namu
over the past seven thousand years. Pacific salmon was the most prevalent species of fish
uncovered within the midden, excluding herring. Pink, chum and sockeye species were
consumed in the greatest quantities. Pink was particularly favored because of its ability to
store over winter months without spoiling. Evidence from the shell midden also reveals
fluctuations within the pink salmon fishery from ~3800 until 1900 cal year BP. The
paleoenvironmental conditions within Namu Lake during the time of the pink collapse
have never before been explored. There is also little evidence pertaining to what may
have contributed to the collapse of the pink fishery.
Sediment cores collected from Namu Lake, B.C. provide evidence for
paleoenvironmental conditions that may have contributed to fluctuations in the pink
salmon population. Particle size analyses of lake sediment cores indicate changes in river
discharge as well as erosional intensity within the Namu basin. Particle size, coupled with
radiocarbon dating, reveal a transitional period within the basin from ~ 3200 to 2200 cal
year BP. A decrease in elemental ratios/Al, particularly Ca, Na, Ba, and Sr, provides
evidence for a decline in erosional intensity and a relatively drier period within the basin.
The decrease in erosional intensity could be due to consistently drier conditions at Namu.
A resulting reduction in the flow of the Namu River would have caused an increase in
finer particles within the pink salmon spawning grounds. Average C/N ratios for NC1 are
26.28, indicating that organic matter within the lake is mainly terrestrial in origin. These
results, combined with the particle size and trace metal analysis, reveal that river
discharge and slope wash had declined during this period causing fine material to remain
in the Namu River (outflowing), which is the spawning grounds for the pink salmon,
rather than being transported out into the bay. The results of this study reveal that a shift
in moisture, towards relatively dry conditions, negatively impacted spawning pink salmon
at Namu Lake. This study provides insight into the sensitivity of Pacific salmon to
climate and the effects future climate change may have on the species. The ability of
environmental data to supplement and enhance archaeological information and
interpretations of prehistoric conditions is illustrated throughout this study. The cores
collected at Namu Lake also reveal the need for site specific climatic data in order to
accurately interpret archaeological contexts and conditions. / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/20574 |
| Date | January 2016 |
| Creators | Brown, Alyson |
| Contributors | Reinhardt, Eduard, Earth Sciences |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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