Likely locations of sea turtle stranding mortality using experimentally-calibrated, time and space-specific drift models

Sea turtle stranding events provide an opportunity to study drivers of mortality, but causes of strandings are poorly understood. A general sea turtle carcass oceanographic drift model was developed to estimate likely mortality locations from coastal sea turtle stranding records. Key model advancements include realistic direct wind forcing on carcasses, temperature driven carcass decomposition and the development of mortality location predictions for individual strandings. We applied this model to 2009-2014 stranding events within the Chesapeake Bay, Virginia. Predicted origin of vessel strike strandings were compared to commercial vessel data, and potential hazardous turtle-vessel interactions were identified in the southeastern Bay and James River. Commercial fishing activity of gear types with known sea turtle interactions were compared to predicted mortality locations for stranded turtles with suggested fisheries-induced mortality. Probable mortality locations for these strandings varied seasonally, with two distinct areas in the southwest and southeast portions of the lower Bay. Spatial overlap was noted between potential mortality locations and gillnet, seine, pot, and pound net fisheries, providing important information for focusing future research on mitigating conflict between sea turtles and human activities. Our ability to quantitatively assess spatial and temporal overlap between sea turtle mortality and human uses of the habitat were hindered by the low resolution of human use datasets, especially those for recreational vessel and commercial fishing gear distributions. This study highlights the importance of addressing these data gaps and provides a meaningful conservation tool that can be applied to stranding data of sea turtles and other marine megafauna worldwide.

Keyword(s)

Sea turtle strandings, Sea turtle mortality, Chesapeake Bay, Drift simulations, Fisheries and vessel interactions, Endangered species, Marine conservation, Protected species management

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Fig. A.1. Frequency of all reported stranding events per week of the year for 2009–2014. Shaded areas represent the spring peak (red; 3–5 weeks) and the remainder of the stranding ...
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Fig. A.2. Virginia Marine Resource Commission waterways (black outline) and system (color) identification. (For interpretation of the references to color in this figure legend, the reader is referred
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Fig. A.3. Harvest (hundreds of thousands of pounds) by (A) staked gillnet and (B) pound net gear. Data was obtained from the Virginia Marine Resource Commission and ...
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Supplementary material
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Author's final draft
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How to cite
Santos Bianca S., Friedrichs Marjorie A. M., Rose Sarah A., Barco Susan G., Kaplan David M. (2018). Likely locations of sea turtle stranding mortality using experimentally-calibrated, time and space-specific drift models. Biological Conservation. 226. 127-143. https://doi.org/10.1016/j.biocon.2018.06.029, https://archimer.ifremer.fr/doc/00462/57357/

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