Data from: Fossil dermal denticles reveal the pre-exploitation baseline of a Caribbean coral reef shark community

Pre-exploitation shark baselines and the history of human impact on coral
reef-associated shark communities in the Caribbean are poorly understood.
We recovered shark dermal denticles from mid-Holocene (~7 ka) and modern
reef sediments in Bocas del Toro, Caribbean Panama to reconstruct an
empirical shark baseline before major human impact and quantify how much
the modern shark community in the region had shifted from this historical
reference point. We found that denticle accumulation rates, a proxy for
shark abundance, declined by 71% since the mid-Holocene. All denticle
morphotypes, which reflect shark community composition, experienced
significant losses, but those morphotypes found on fast swimming, pelagic
sharks (e.g., families Carcharhinidae and Sphyrnidae) declined the most.
Analysis of historical records suggested that the steepest decline in
shark abundance occurred in the late 20th century, coinciding with the
advent of a targeted shark fishery in Panama. Although the
disproportionate loss of denticles characterizing pelagic sharks was
consistent with overfishing, the large reduction in denticles
characterizing demersal species with low commercial value (i.e., the nurse
shark Ginglymostoma cirratum) indicated that other stressors could have
exacerbated these declines. We demonstrate that the denticle record can
reveal changes in shark communities over long ecological timescales,
helping to contextualize contemporary abundances and inform shark
management and ecology.