The Behavioral Ecology of Shellfish Gathering in Western Kiribati, Micronesia 1: Prey Choice

Abstract

Focusing on contemporary shellfish exploitation among several atoll communities in Kiribati, Micronesia, this paper examines the relationship between human foragers and their invertebrate prey via the prey choice or diet breadth model derived from optimal foraging theory. Shellfish, like many other reef organisms, are relatively sedentary and predictable, but these characteristics make them susceptible to over-harvesting. The research reveals that shellfish gatherers are foraging in a manner that matches the predictions of optimal foraging theory. The work adds to our understanding of optimal foraging decisions in atoll settings by critically evaluating the depiction of atoll dwellers as conservationists.

The Behavioral Ecology of Shellfish Gathering in Western Kiribati, Micronesia. 2: Patch Choice, Patch Sampling, and Risk

“…As shown in a previous analysis (Thomas 2007), shellfish gatherers from communities sampled on five atolls behaved according to the prediction of the prey choice or diet breadth model, one of the simplest OFT models. Briefly stated, the model ranks acquired resources according to their profitability, usually expressed in terms of net energy per unit foraging time.…”

“…4 Return rates for T. gigas and H. hippopus are variable, no doubt because of the wide range in size of individual prey items. Nevertheless, they may be regarded as high-ranking prey, but still inferior to most other marine resources, as reported in a previous study on prey choice (Thomas 2007). The fact that both taxa are taken incidentally is in itself revealing.…”

“…Should the targeted prey be another bivalve, such as Asaphis violascens, attention is focused in gravelly sands, close to shore. Table II lists the main patches found 1 Details of sampling methodology and the sociocultural context of shellfish harvesting can be found in Thomas (1999Thomas ( , 2003aThomas ( , 2007. The I-Kiribati recognize three main patches in the intertidal to shallow subtidal regions of the lagoon: (1) nearshore; (2) sand flat; and (3) seagrass.…”

“…As in the first paper in this series, which discusses the prey choice model (Thomas 2007), the goal is to enhance our knowledge of optimal foraging theory (OFT) among tropical intertidal gatherers and to assess the findings in relation to local conservation issues in an atoll setting.…”

Is Meat Flavor a Factor in Hunters’ Prey Choice Decisions?

“…Ethnographic tests in a broad variety of environmental and social contexts have provided general support for the predictive power of the prey choice model (O'Connell and Hawkes 1981;Winterhalder 1981;Hill et al 1987;Kuchikura 1988;Smith 1991;Alvard 1993;Thomas 2007). That is, human hunters appear to focus on prey types that, on average, increase their overall return rate.…”