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The complexity of trade networks is a major challenge to controlling wildlife trafficking and illegal, unreported, and unregulated (IUU) fishing. These networks may not be modern inventions, but have developed over centuries, from integrated global markets that preceded modern regulatory policies. To understand these linkages, we curated 150 years of tortoiseshell transactions and derived biologically informed harvest models to estimate the trade in critically endangered hawksbill sea turtles ( Eretmochelys imbricata ). We find that trade networks concentrated in Southeast Asia harvested 9 million turtles, over six times previous estimates. These networks spread from within the Pacific, to the Indian and Atlantic basins, and became markedly more complex after 1950. Our results further indicate that the magnitude and extent of the coastally restricted hawksbill exploitation parallel current patterns of IUU fishing. Policies to combat these interlinked illegal practices should assimilate the important role of small-scale, coastal fisheries in these increasingly complex global networks.

Some of the most basic questions of sea turtle life history are also the most elusive. Many uncertainties surround lifespan, growth rates, maturity and spatial structure, yet these are critical factors in assessing population status. Here we examine the keratinized hard tissues of the hawksbill (Eretmochelys imbricata) carapace and use bomb radiocarbon dating to estimate growth and maturity. Scutes have an established dietary record, yet the large keratin deposits of hawksbills evoke a reliable chronology. We sectioned, polished and imaged posterior marginal scutes from 36 individual hawksbills representing all life stages, several Pacific populations and spanning eight decades. We counted the apparent growth lines, microsampled along growth contours and calibrated Δ(14)C values to reference coral series. We fit von Bertalanffy growth function (VBGF) models to the results, producing a range of age estimates for each turtle. We find Hawaii hawksbills deposit eight growth lines annually (range 5-14), with model ensembles producing a somatic growth parameter (k) of 0.13 (range 0.1-0.2) and first breeding at 29 years (range 23-36). Recent bomb radiocarbon values also suggest declining trophic status. Together, our results may reflect long-term changes in the benthic community structure of Hawaii reefs, and possibly shed light on the critical population status for Hawaii hawksbills., (© 2016 The Author(s).)