SIZE OF OYSTERS EATEN BY INDIGENOUS NEW YORKERS AND TODAY

The decline in size of eastern oysters (Crassostrea virginica) valves due to human harvesting is well-documented. Yet, most estimates have compared the harvested oysters discarded by humans to live oysters. Here we test the hypothesis that New York’s oysters have declined by comparing oysters harvested by humans in two time slices: those harvested by Indigenous Nations in the archaeologically-defined Middle and Late Woodland periods (~1500 to 1000 yBP) to those eaten by diners in New York City today.

We measured the size of 29 oyster valves accumulated in middens from the Piping Rock archaeological site. Piping Rock lies on the east bank of the Hudson River in Ossining, New York, approximately 55km north of the mouth of the Hudson River. Indigenous people gathered oysters seasonally from locales, such as Piping Rock, year after year. Oyster valves accumulated in so-called sheet middens that represent discard over multiple seasons.

We compared these valves to 125 valves collected from restaurant discards on City Island, Bronx by a grassroots group reintroducing oysters to City Island waters. City Island lies in western Long Island Sound and most oysters sold to restaurants on City Island are farmed.

We find that, contrary to expectations, oysters eaten by the Indigenous population were smaller on average than oysters eaten by modern diners. Additionally, oysters collected from Indigenous middens were significantly more variable in size than oysters eaten by modern diners. These comparisons remain significant following subsampling of modern samples to match the smaller sample size of Middle and Late Woodland shells.

We propose a few explanations for this pattern: A) modern diners prefer larger oysters, B) Piping Rock oysters were harvested over a limited area, resulting in oyster discards of varying sizes, C) the Indigenous population left a large fraction of larger oysters unharvested, and/or D) modern-day farmed-oysters are more protected from predation than oysters harvested by Indigenous people, allowing the oysters to grow to larger size. Further work will focus on teasing out these hypotheses and expanding temporal and spatial range by reviewing additional archaeological samples and modern-day restaurant discards.