Element identification protocols and analytical bias in Pacific archaeofish assemblages: A review of recent studies and a new case from Hawai‘i

Abstract

The identification of skeletal elements in prehistoric archaeofish assemblages allows for the reconstruction of subsistence, exploitation strategies, and changes in ecology and environment over time. In the Pacific, the identification of fish bone has historically been undertaken using five paired jaw elements and variety of “special” bones that are diagnostic to specific taxa. Over the last 30 years, a number of studies have called for the identification of a wider suite of elements than previously used, or all skeletal elements, to better capture assemblage taxonomic composition. This thesis focuses on two aspects of this methodological issue. First, recent Pacific fish studies that use a wider suite of elements for identification, are systematically reviewed to evaluate their findings. This examination focuses on five research questions that consider how element preservation and selection affect sample size, richness, and taxonomic abundance. The elements that are most commonly identified in Pacific archaeofish studies, and which consistently increase the number of identified specimens (NISP) and sample richness, are established. The second component examines a fish assemblage from a new biogeographic area, the subtropical Hawaiian Islands. In this large, well-preserved assemblage of 20,110 fish bones from a rockshelter site in Ka‘ūpūlehu, Hawai‘i Island, all cranial and postcranial elements were analysed. The Ka‘ūpūlehu findings are compared to an archaeofish study conducted at the same site, and then others in the island group. This comparison suggests that a reliance on the five paired jaw elements and “specials” protocol consistently results in lower overall NISP and richness, as well as an over-representation of certain reef fish families. The Ka‘ūpūlehu results generally mirror the Pacific studies, except certain elements from the oromandibular region (the five paired mouth bones and palatine) were underrepresented. The fragile nature of the cranial elements of two top taxa, Acanthuridae and Pomacentridae, likely drive this disparity. In systematically reviewing the impact of element selection on identified sample size, taxonomic richness, and abundances, this thesis further demonstrates the importance of analytical decisions relating to element selection. This research augments existing methodological studies in the Pacific by considering this in a new biogeographic and cultural area, Hawai‘i. Lastly, while several studies recommend Pacific zooarchaeologists consider all skeletal elements for taxonomic identifications, this research found that some elements routinely represent more fish families, and consistently alter NISP and taxonomic richness. These are the ceratohyal, cleithrum, hyomandibular, opercular, palatine, parasphenoid, preopercular, scapula, supracleithrum, and vertebrae. Others elements were found to be poorly represented or rarely identified, and not particularly useful for identification protocols. It is recommended that a wider suite of elements than the five paired jaw bones and “specials” be used in Pacific identification protocols. Rather than suggesting a specific set of elements, this thesis proposes that the elements used for analysis be determined by the research questions being asked and any study-specific analytical constraints (e.g., comparative collections, sample size).