Truly Long-Term Sustainability: An Archaeological Analysis of Oyster Shells

Abstract

The simultaneous effects of today's population growth and climate change are endangering the world's vulnerable resources. Oyster reefs, which provide vital ecological services, have an estimated 85% loss from historical levels worldwide. This loss threatens the sustainability of current high-intensity industrial oyster harvesting practices. Fortunately, a deeper time perspective on oyster harvesting provides insight to policy options for sustaining the industry into the distant future. During the 19th century, Cedar Key, Florida was among the largest oyster exporters in the U.S. Two-thousand years earlier, the area was teeming with aboriginal communities that harvested oysters and collected the inedible remains in huge mounds and middens. One such site, Shell Mound, just north of Cedar Key, is a 7-m-tall, 200-m-wide shell ring that was erected in only a couple of centuries. This construction followed a period of another 2,000 years during which oysters were routinely collected and consumed in large quantities. With such large-scale harvesting over four millennia, native people employed a strategy of resiliency to sustain their maritime economies. With case material from parallel native experiences in the Chesapeake region, I illustrate how oyster harvesting was diversified to include wider catchments and less selectivity through time. While these data suggest that native shellfishers experienced downturns in local production, niche expansion and diversification enabled recovery of local oyster beds and supported, in the long-term, sustained settlement without disruption in occupation or economy. The methods employed in the Chesapeake study can be used to examine long-term oyster harvesting in the Cedar Key region, an area that is currently suffering decreasing yields due to climate change, diminished water quality, and underregulated harvesting. Although contemporary ecological studies provide short-term assessments of changes in oyster populations, an understanding of multicentury exploitation, such as what can be offered by archaeological data, is crucial for successfully creating a long-term future in sustainable oyster exploitation.

Millennial-scale sustainability of the Chesapeake Bay Native American oyster fishery

“…Together, these data demonstrate a range of human influence on oyster size in the past but general resilience to Native American harvest pressure in several North American C. virginica populations. These data add to a growing body of research around the world that documents a continuum of ancient human influence on shellfish populations, ranging from human-induced reduction of shellfish size from overexploitation to continuity and size increases that may have resulted from changing environmental variables, especially nutrient increases (26)(27)(28)(29)(30)(35)(36)(37)(38)(39)(40).…”

“…Although our study is the first, to our knowledge, to analyze oyster size throughout the Chesapeake Bay, a few archaeological studies have investigated past oyster size at single sites or localized areas (9,26,27). Data from the White Oak Point site in Virginia provide the longest sequence from a single site in the region.…”

“…Previous studies of past Chesapeake oyster populations include estimates of reef accretion rates (17,23), analysis of how historical nutrient input may have resulted in larger oyster sizes (21), evidence for colonial-period drought and higher estuarine salinity (24), changes in oyster growth rates from late prehistoric to modern times (25), and the possibility of localized overharvest during the colonial period (9,20). However, there has been limited investigation into prehistoric Native American impact on Chesapeake Bay oysters, with previous studies limited to a single site or localized area (26,27).…”

Discarding the evidence: The place of natural resources stewardship in the creation of the Peel Island Lazaret Midden, Moreton Bay, southeast Queensland

“…Although it is generally recognised that shell midden deposits are created by the accumulation of cultural remains resulting from human behaviour related to subsistence activity (Meehan, 1982;Waselkov, 1987;Alvarez et al, 2010;Andrus, 2011), it is also well documented that there may be a range of external (Waselkov, 1987;Erlandson and Rick, 2008;Ulm, 2011;Rowland and Ulm, 2012) and biological (Kent, 1992;Jenkins, 2013) factors that impact on the survival of shell and other cultural material at midden sites, often differentially. Erlandson and Rick (2008) and Rowland and Ulm (2012) have argued that, prior to seeking socio-cultural explanations for variation in artefact discard in shell midden sites, it is important that any likely external impacts on the survival of cultural remains are considered.…”

“…Severe storms and floods can create significant water turbidity that adversely affects the growing environment for oysters (Kent, 1992;Jenkins, 2013). Flooding associated with cyclones and severe tropical storms creates the level of turbidity required to kill sea grass beds and to also have adverse effects on other marine ecosystems, including oyster reefs (Carruthers et al, 2002).…”