Ancient Engineering of Fish Capture and Storage in Southwest Florida
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Ancient engineering of fish capture and storage in southwest Florida Victor D. Thompsona,b,1, William H. Marquardtc, Michael Savaresed, Karen J. Walkerc, Lee A. Newsome, Isabelle Lulewicza, Nathan R. Lawresf, Amanda D. Roberts Thompsonb, Allan R. Bacong, and Christoph A. Walserh aDepartment of Anthropology, University of Georgia, Athens, GA 30602; bLaboratory of Archaeology, University of Georgia, Athens, GA 30602; cFlorida Museum of Natural History, University of Florida, Gainesville, FL 32611; dDepartment of Marine and Earth Sciences, Florida Gulf Coast University, Fort Myers, FL 33965; eSchool of Humanities and Sciences, Flagler College, St. Augustine, FL 32084; fDepartment of Anthropology, University of West Georgia, Carrolton, GA 30118; gDepartment of Soil and Water Science, University of Florida, Gainesville, FL 32611; and hDepartment of Biology, The College of Idaho, Caldwell, ID 83605 Edited by Christopher B. Rodning, Tulane University, New Orleans, LA, and accepted by Editorial Board Member Elsa M. Redmond February 24, 2020 (received for review December 19, 2019) In the 16th century, the Calusa, a fisher-gatherer-hunter society, were evaluation of these features that allows for an interpretation of the most politically complex polity in Florida, and the archaeological their function. Our work at the site of Mound Key (8LL2) reveals site of Mound Key was their capital. Based on historic documents, the the complex engineering behind these structures, as well as de- ruling elite at Mound Key controlled surplus production and distri- tails of their chronology and function (Fig. 1). We suggest that bution. The question remains exactly how such surplus pooling these structures functioned as large-scale fish traps and storage occurred and when such traditions were elaborated on and reflected facilities for live fish surpluses. in the built environment. Our work focuses on the “watercourts” and During the 16th century, Mound Key was the capital of the associated areas at Mound Key. These subrectangular constructions Calusa kingdom, which stretched from the Florida Keys to just of shell and other sediments around centralized inundated areas have south of Tampa Bay (16, 17). Mound Key is located in Estero been variously interpreted. Here, we detail when these enclosures Bay, FL, and is an anthropogenic island comprised mostly of were constructed and their engineering and function. We argue that midden shell and other sediments (18); in the 17th century, these structures were for large surplus capture and storage of aquatic Mound Key had a population of ca. 1,000 (19). The site covers resources that were controlled and managed by corporate groups. ca. 51 ha and is a complex arrangement of midden-mounds, canals, watercourts, and other features. By AD 1000, the in- archaeology | Calusa | Florida | fisher-gatherer-hunters habitants had engaged in substantial modification to the island, with the two largest mounds (mounds 1 and 2) reaching eleva- he study of hydrological engineering in the ancient world has tions of around 10 m and 6 m, respectively. Our research on Tlong fascinated archaeologists, many of whom saw such ar- mound 1 documents at least three phases of construction and chitectural feats as integral to the development of the state and repair for a large building(s) beginning around AD 1000. The linked primarily to agricultural production. Less frequently last iteration of the mound 1 structure is what we interpret as the discussed is the role that such engineering played in the devel- “house” of Caalus, the mid-16th century Calusa king. According opment of nonagricultural societies, specifically those that relied to Spanish documents, it was able to hold 2,000 people, and it is upon aquatic resources. Indeed, such resources are thought to where Pedro Menéndez de Avilés, the first governor of La have been the foundations of cultural complexity elsewhere in the Florida, met the king and discussed terms (19, 20). Our finding of world (1–4). While most researchers are familiar with capture these structures indicates that mound 1 was the likely seat of technologies, we are only now beginning to understand these power for a long-lived corporate group for around 500 y (20). engineered structures as they relate to storage and management – (5 8). This research takes important steps in enhancing our un- Significance derstanding of fishing societies that engage in complex engineer- ing and the social and ecological relationships that they engender. The focus of our research in Florida centers on how the Calusa Fish were captured and stored by Native Americans of southwest- (9–11), a fisher-gatherer-hunter society, created, maintained, ern Florida in complex walled structures called watercourts, con- and distributed surpluses of aquatic and wetland resources. Our structed of shell and other sediments. These structures were engineered with knowledge of tidal systems, hydrology, and the main research question is how such groups stored fish in the biology of species to be stored in these courts. This work documents absence of refrigeration in the warm, subtropical environment of the considerable ability of the Calusa, a nonagricultural society, to southwest Florida. Some of the more intriguing architectural engineer systems that significantly alter their natural environment. features in this region include “watercourts” found at several These structures are associated with an ever-growing population large shell midden/mound sites (12). We define these water- and complex system of governance among the Calusa of Florida. courts as subrectangular constructions of shell and other sedi- ments around centralized inundated areas. The earliest interpretation Author contributions: V.D.T., W.H.M., M.S., and K.J.W. designed research; V.D.T., W.H.M., of these features was that they were for fish storage (13); how- M.S., K.J.W., L.A.N., I.L., N.R.L., A.D.R.T., A.R.B., and C.A.W. performed research; V.D.T., ever, no research has systematically evaluated their timing of W.H.M., M.S., K.J.W., L.A.N., I.L., N.R.L., A.D.R.T., A.R.B., and C.A.W. analyzed data; and construction and function. Many, however, have speculated V.D.T., W.H.M., M.S., K.J.W., I.L., N.R.L., and A.R.B. wrote the paper. widely on their function without conducting the excavations The authors declare no competing interest. necessary to evaluate these ideas. For example, Schober (14) This article is a PNAS Direct Submission. C.B.R. is a guest editor invited by the Editorial argues that the Calusa managed conch ponds, presumably in Board. water courts. We find this interpretation untenable for a number Published under the PNAS license. of reasons that we outline in a recent work (15), with the main See online for related content such as Commentaries. reason being that juvenile marine gastropods prefer shallow, 1To whom correspondence may be addressed. Email: [email protected]. seagrass-rich environments that would have been difficult to This article contains supporting information online at https://www.pnas.org/lookup/suppl/ duplicate in watercourts. Thus, while many have speculated over doi:10.1073/pnas.1921708117/-/DCSupplemental. the years, the work presented here represents a systematic First published March 30, 2020. 8374–8381 | PNAS | April 14, 2020 | vol. 117 | no. 15 www.pnas.org/cgi/doi/10.1073/pnas.1921708117 Downloaded by guest on September 29, 2021 ANTHROPOLOGY Fig. 1. LiDAR digital elevation model of Mound Key showing the site’s prominent features. The available evidence indicates that the Calusa had a large how did they relate to the timing of construction of large-scale population (ca. 20,000) and were one of the most politically storage facilities? To address these questions, we conducted complex groups of hunter-gatherers of the ancient world. Thus, remote sensing and archaeological excavations at one of Mound we are left with one central question: How did the Calusa at Key’s watercourts in 2017 (Fig. 2). Mound Key provide and sustain food sufficient for the complex political and social life observed in the 16th century? We argue Remote Sensing that part of the answer to this is that the Calusa engineered Light detection and ranging (LiDAR) data on the watercourts sophisticated landscapes for the capture and storage of live indicate that the East Court and the West Court enclose a total surpluses of fish, which could have been obtained on a regular of around 6,000 square meters of mangrove wetlands. The East basis in the inshore estuarine bays. Court measures ca. 42 m in maximum width and ca. 70 m long ’ While Mound Key s layout changed over time, it is clear that along its longest axis. The West Court measures ca. 50 m wide at the canals, watercourts, and other features were thoughtfully its widest and ca. 75 m along its longest axis. The East Court is engineered. Given its location in Estero Bay, its engineers had to slightly smaller than the West Court, ca. 2,670 and ca. 3,350 consider the effects of the low-amplitude (<1 m) mixed tidal square meters, respectively. The average berm height of both is pattern of the Florida Gulf Coast. Bisecting Mound Key’s two ca. 1 m. main midden-mound complexes is a central Grand Canal run- Each court has an opening in the berm on the northernmost ning approximately southwest to northeast, measuring around 365 m long and averaging 28 m wide. At its northern terminus, section facing the Grand Canal measuring ca. 10 to 12 m wide. It the canal (today a wetland) opens up to constructed causeways of is these breaks that we believe were once the locations of gates shell ridges and burial mounds. Several tributary canals break off made of perishable materials (e.g., wood, fiber), similar to those ’ the main canal at right angles and lead to other areas of the site.