UC Santa Cruz

This research uses California's Monterey Bay as a case study for analyzing human decisions in acquiring marine fishes through different climatic regimes. I address behavioral, ecological, and biological aspects of fish species that affect their value to human diet. I also critically examine local evidence for Holocene climate changes. I question the common archaeological assumption that energetic rate of return is the key variable in prey taxa ranking and employ dynamic state variable modeling, long used in ecology, to predict optimal diet decisions. I assess how prior descriptions of Central Coast culture history compare to climatic evidence, model predictions, and my faunal analysis results.

I analyzed fish remains from 13 Monterey Bay area sites, representing multiple habitats and cultural periods, producing data on taxonomic distributions, modifications, and fragmentation. I radiocarbon dated fish specimens from each site to assess how these accorded with dates on other material and analyzed proximate compositions of several nearshore species to elucidate the role of nutrition in prey selection.

Dynamic state variable modeling suggests that probability of successful prey capture, mortality risk in a patch, and energy expenditure are very important in a forager's prey choices. The model predicts that foragers preferentially exploit predictable, easily acquired resources, even those with relatively lower rates of return. This prediction is borne out in the archaeofaunal data.

Fish faunas show statistically significant shifts in prey types acquired in similar habitats over time. Sardines are common through time and dominate the later periods' archaeofaunas. Their abundance increases markedly during the Medieval Climatic Anomaly, suggesting they may have been valued for their high fat content. Sharks and rays are abundant only in the earliest estuary sites, most likely declining due to habitat degradation. Tidepool fishes rise from ubiquitous but low proportions to nearly a third of identified specimens in the last thousand years, suggesting heavy dependence on marine resources continued to historic contact.

Results indicate that people did not always acquire the nearest and most easily caught prey, as previous studies have suggested. People sometimes emphasized more difficult and dangerous patches and responded to changes in habitat and climate.