The unique functioning of a pre-Columbian Amazonian floodplain fishery

Rumsaïs Blatrix,Philippe Béarez,Doyle Mckey,Marc Pouilly,Mashuta Kalebe,Jose Luis Aramayo,Gabriela Prestes-Carneiro,Mark Robinson,Cyril Bernard,Leonor Rodrigues,Marcelo Amaya,Mélisse Durécu,Umberto Lombardo,Jose Iriarte,Alex Ovando,Carl F Huchzermeyer,Bruno Roux,Jonas Gregorio De Souza

doi:10.1038/s41598-018-24454-4

Abstract

Archaeology provides few examples of large-scale fisheries at the frontier between catching and farming of fish. We analysed the spatial organization of earthen embankments to infer the functioning of a landscape-level pre-Columbian Amazonian fishery that was based on capture of out-migrating fish after reproduction in seasonal floodplains. Long earthen weirs cross floodplains. We showed that weirs bear successive V-shaped features (termed ‘Vs’ for the sake of brevity) pointing downstream for outflowing water and that ponds are associated with Vs, the V often forming the pond’s downstream wall. How Vs channelled fish into ponds cannot be explained simply by hydraulics, because Vs surprisingly lack fishways, where, in other weirs, traps capture fish borne by current flowing through these gaps. We suggest that when water was still high enough to flow over the weir, out-migrating bottom-hugging fish followed current downstream into Vs. Finding deeper, slower-moving water, they remained. Receding water further concentrated fish in ponds. The pond served as the trap, and this function shaped pond design. Weir-fishing and pond-fishing are both practiced in African floodplains today. In combining the two, this pre-Columbian system appears unique in the world.

Highlights

Archaeological artefacts document diverse fish-capturing gear, from spears and hooks to nets, traps and weirs[1,2], and rock art depicts fishing scenes, including fish traps[3,4,5], the large-scale ecological functioning of fisheries and its consequences for the social organisation of fishing activities in the past are often difficult to infer
A second archaeological example of a large-scale, relatively intensive inland fishery is the pre-Columbian floodplain fishery based on an extensive network of earthen fish weirs and ponds that was described by Erickson[24,25,26] within a localised region of Bolivia’s Llanos de Moxos in southwestern Amazonia. (In keeping with common practice, ‘pre-Columbian’ is used here to refer to indigenous cultures in the Americas before their extensive alteration by contact with Europeans, which in some regions occurred long after 1492)
We identified three stratigraphic units which we sampled for geochemical analyses and radiocarbon dating

Summary

Introduction

Archaeological artefacts document diverse fish-capturing gear, from spears and hooks to nets, traps and weirs[1,2], and rock art depicts fishing scenes, including fish traps[3,4,5], the large-scale ecological functioning of fisheries and its consequences for the social organisation of fishing activities in the past are often difficult to infer. Greene et al.’s analysis of human modifications of the landscape, combined with knowledge of fish behaviour and ecology, enabled them to make inferences about the system’s functioning Clam gardens provide another example where archaeological vestiges, combined with experimental studies of present-day reconstructions, yield insights into the functioning of a sophisticated coastal fishery[12,13,14,15]. A second archaeological example of a large-scale, relatively intensive inland fishery is the pre-Columbian floodplain fishery based on an extensive network of earthen fish weirs and ponds that was described by Erickson[24,25,26] within a localised region of Bolivia’s Llanos de Moxos in southwestern Amazonia. Weirs function to channel fish movement, with V-shaped structures concentrating fish at particular points where they can be much more captured than if they were dispersed throughout the vast floodplain

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Conclusion