Using Fish Remains to Trace Dynamic Exchanges Between Ecology and Economy in Fiji

Abstract

Island nations in the developing world are some of the communities most at-risk to the effects of climate change and are under increasing pressure from globalized seafood markets. Indigenous Fijians have a stark understanding of environmental change because of their economic and dietary reliance on marine resources, including shark fisheries and tourism. Sharks are important apex predators with deep cultural significance in Fiji and they are thus useful species to focus on when investigating historical ecology. However, they are difficult to study; sharks have cartilaginous skeletons, making full body fossils rare, and their behavior can make them difficult to survey with traditional methods. Sharks are also covered in dermal denticles which they shed throughout their lives and which compose some of the most extensive and oldest fossil types. All fish, including sharks, also shed their teeth, and together these microfossils are called ichthyoliths. Scientists in the Caribbean have developed innovative techniques to use ichthyoliths to illuminate the importance of parrotfish to coral reef ecology and trace historical and pre-anthropogenic shark populations. However, this microfossil approach has not yet reached Fiji. We developed a trait-based character coding scheme to describe denticle morphology based on both modern denticles and fossil denticles and discuss our work to expand current denticle reference collections. When combined with ecological factors, morphological analysis can identify temporal periods and spatial regions of importance in both modern and paleo-ocean ecosystem dynamics and aid historical ecologists in describing shark communities of the past. We are embarking on a research project to collect cores from Fiji to examine parrotfish and shark ecology through time. Here we summarize the methods we will use and how we have tailored them to our study region and invite input from the conservation paleobiology community on our study design.