image: Researcher collecting bulk surface sediment samples from a modern coral reef in Bocas del Toro, Panama. view more
Credit: Image credit: Sean Mattson (International Center for Tropical Agriculture, Cali, Colombia).
Human activity has led to a severe decrease in Caribbean shark abundance, according to a study. The size and diversity of Caribbean shark populations prior to human exploitation have been difficult to quantify due to a lack of long-term empirical data. Erin Dillon and colleagues collected fossil shark dermal denticles, which are microscopic tooth-like scales, from the marine sediments of an approximately 7,000-year-old coral reef in the western Caribbean along the coast of Panama and denticles from three nearby modern reefs to serve as a proxy to estimate the abundance and composition of shark communities before and after human settlement. The authors also compiled and analyzed published records of human habitation and fishing practices to contextualize the data. The dermal denticle assemblages showed a 71% decrease in mean accumulation rates between the two time periods, suggesting that Caribbean sharks may have been up to three times more abundant before humans began using marine resources in the region. The results also showed a shift in the composition of the shark communities, with fast-swimming, pelagic sharks experiencing the largest declines. According to the authors, further research into historical dermal denticle assemblages can improve understanding of the impacts of human exploitation on shark communities over time and help guide conservation efforts in the Caribbean and elsewhere.
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Article #2020-17735 "Fossil dermal denticles reveal the preexploitation baseline of a Caribbean coral reef shark community," by Erin M. Dillon et al.
MEDIA CONTACT: Erin M. Dillon, University of California, Santa Barbara, CA; tel: 650-776-0095; email: <erinmdillon@ucsb.edu>
Journal
Proceedings of the National Academy of Sciences