Biology Faculty Articles
Title
Global collision-risk hotspots of marine traffic and the world’s largest fish, the whale shark
Document Type
Article
Publication Date
5-9-2022
Publication Title
Proceedings of the National Academy of Sciences
Keywords
Ship Strike, Marine Megafauna, Conservation, Movement Ecology, Human Impact
ISSN
0027-8424
Volume
119
Issue/No.
20
First Page
e2117440119
Abstract
Marine traffic is increasing globally yet collisions with endangered megafauna such as whales, sea turtles, and planktivorous sharks go largely undetected or unreported. Collisions leading to mortality can have population-level consequences for endangered species. Hence, identifying simultaneous space use of megafauna and shipping throughout ranges may reveal as-yet-unknown spatial targets requiring conservation. However, global studies tracking megafauna and shipping occurrences are lacking. Here we combine satellite-tracked movements of the whale shark, Rhincodon typus, and vessel activity to show that 92% of sharks’ horizontal space use and nearly 50% of vertical space use overlap with persistent large vessel (>300 gross tons) traffic. Collision-risk estimates correlated with reported whale shark mortality from ship strikes, indicating higher mortality in areas with greatest overlap. Hotspots of potential collision risk were evident in all major oceans, predominantly from overlap with cargo and tanker vessels, and were concentrated in gulf regions, where dense traffic co-occurred with seasonal shark movements. Nearly a third of whale shark hotspots overlapped with the highest collision-risk areas, with the last known locations of tracked sharks coinciding with busier shipping routes more often than expected. Depth-recording tags provided evidence for sinking, likely dead, whale sharks, suggesting substantial “cryptic” lethal ship strikes are possible, which could explain why whale shark population declines continue despite international protection and low fishing-induced mortality. Mitigation measures to reduce ship-strike risk should be considered to conserve this species and other ocean giants that are likely experiencing similar impacts from growing global vessel traffic.
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
NSUWorks Citation
Womersley, Freya C.; Nicolas E. Humphries; Nuno Queiroz; Marisa Vedor; Ivo da Costa; Miguel Furtado; John P. Tyminski; Katya Abrantes; Gonzalo Araujo; Steffen S. Bach; Adam Barnett; Michael L. Berumen; Sandra Bessudo Lion; Camrin D. Braun; Elizabeth Clingham; Jesse E. M. Cochran; Rafael de la Parra; Stella Diamant; Alistair D. M. Dove; Christine L. Dudgeon; Mark V. Erdmann; Eduardo Espinoza; Richard Fitzpatrick; Jaime González Cano; Jonathan R. Green; Hector M. Guzman; Royale Hardenstine; Abdi Hasan; Fábio H. V. Hazin; Alex R. Hearn; Robert E. Hueter; Mohammed Y. Jaidah; Jessica Labaja; Felipe Ladino; Bruno C. L. Macena; John J. Morris Jr.; Bradley M. Norman; Cesar Peñaherrera-Palma; Simon J. Pierce; Lina Maria Quintero; Dení Ramírez-Macías; Samantha D. Reynolds; Anthony J. Richardson; David P. Robinson; Christoph A. Rohner; David R. L. Rowat; Marcus Sheaves; Mahmood Shivji; Abraham B. Sianipar; Gregory B. Skomal; German Soler; Ismail Syakurachman; Simon R. Thorrold; D. Harry Webb; Bradley M. Wetherbee; Timothy D. White; Tyler Clavelle; David A. Kroodsma; Michele Thums; Luciana C. Ferreira; Mark G. Meekan; Lucy M. Arrowsmith; Emily K. Lester; Megan M. Meyers; Lauren R. Peel; Ana M. M. Sequeira; Victor M. Eguiluz; Carlos M. Duarte; and David W. Sims. 2022. "Global collision-risk hotspots of marine traffic and the world’s largest fish, the whale shark." Proceedings of the National Academy of Sciences 119, (20): e2117440119. doi:10.1073/pnas.2117440119.
ResearcherID
G-4080-2013
DOI
10.1073/pnas.2117440119
Comments
The derived mean shark relative spatial density and data underlying Fig. 4A (map of mean shark–vessel spatial overlap and CRI) and Fig. 4B (plot of spatial overlap and CRI) is freely available on GitHub (https://github.com/GlobalSharkMovement/GlobalCollisionRisk) (38).