Middle to Late Holocene near-shore foraging strategies at Caution Bay, Papua New Guinea

Abstract

Caution Bay, on the South Coast of Papua New Guinea, offers a unique opportunity to assess the possible impacts of predation by pre-Lapita, Lapita, and post-Lapita peoples on local mollusc resources from at least 5000 years ago. Using biometric analysis of the bivalve Anadara antiquata and gastropod Conomurex luhuanus from the site of Tanamu 1, we examine trends in size and maturity variability through time. Results indicate a reduction in valve size of A. antiquata from c. 5000–2800 cal BP (the pre-Lapita period) to c. 2800–2750 cal BP (falling during the Lapita period), while C. luhuanus undergoes a change in maturity categories between the Lapita period and c. 700–100 cal BP (post-Lapita), with the latter containing lower proportions of both immature and mature individuals. Considering that these two mollusc taxa have the capacity to resist high predation pressures through their reproductive strategies and growth rates, in combination with low discard rates throughout Tanamu 1, it is unlikely that the observed trends are solely related to human predation. Rather, set against a context of significant environmental variability and shifting habitats through time, the pre-Lapita, Lapita, and post-Lapita phases represent significant socio-economic changes, whereby there is a shift from mobile foraging to an increasing reliance upon agriculture. It is therefore likely that there were a range of environmental and socio-economic factors influencing mollusc harvesting and the foraging economy more broadly through time.