Exploitation of loco, Concholepas concholepas (Gastropoda: Muricidae), during the Holocene of Norte Semiárido, Chile

Abstract

This paper is a contribution to the understanding of the possible causes leading to changes in size frequency, species distribution, and abundance of Concholepas concholepas during the Holocene. We present a review of more than 200 archaeological sites and shell middens at Los Vilos (31º55’S, 71º32’W), Provincia de Choapa, Norte Semiárido of Chile spanning for approximately 10,000 years. We synthesize our current knowledge on how populations of C. concholepas living in this locality were affected by the pre-Hispanic human exploitation and by changes in the environment occurred since the Pleistocene. Changes in diversity and abundance of loco and other molluscs during this period were most probably caused by paleoclimatic changes than human behaviour. Through the Early Holocene, coastal occupation was permanent and human subsistence depended on marine resources, locals gathered a wide variety of species but intensively exploited few of them. During the Middle Holocene, humans occupied the coast only seasonally, when shellfish gathering was easy to predict and molluscs were abundant. There was intensive exploitation of some marine mollusc species as well as a greater dependence on terrestrial species. The collection of marine species in 6,500 B.P. was associated to more arid and dry climate conditions, scarcity of other resources, and changes in the sea level. During the Late Holocene, climatic conditions more similar to those present today, allowed the proliferation of coastal settlements exploiting a variety of resources. Our study suggests that marine resources were not necessarily overexploited by humans from Los Vilos, and recorded changes in shell size, abundance, and availability of loco were minimal both in temporal and spatial scales during the Holocene.