Global collision-risk hotspots of marine traffic and the world's largest fish, the whale shark
Global vessel traffic is increasing alongside world economic growth. The potential for rising lethal ship strikes on endangered species of marine megafauna, such as the plankton-feeding whale shark, remains poorly understood since areas of highest overlap are seldom determined across an entire species range. Here the authors show how satellite tracking whale sharks and large vessel movements globally provides a means to localize high-overlap areas and to determine how collision risk changes in time. The authors' results point to potential high levels of undetected or unreported ship strikes, which may explain why whale shark populations continue to decline despite protection and low fishing-induced mortality. Collision mitigations in high-collision-risk areas appear necessary to help conserve this iconic species. 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 the authors 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.
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Authors:
- Womersley, Freya C
- Humphries, Nicolas E
- Queiroz, Nuno
- Vedor, Marisa
- da Costa, Ivo
- Furtado, Miguel
- Tyminski, John P
- Abrantes, Katya
- Araujo, Gonzalo
- Bach, Steffen S
- Barnett, Adam
- Berumen, Michael L
- Lion, Sandra Bessudo
- Braun, Camrin D
- Clingham, Elizabeth
- Cochran, Jesse E M
- de la Parra, Rafael
- Diamant, Stella
- Dove, Alistair D M
- Dudgeon, Christine L
- Erdmann, Mark V
- Espinoza, Eduardo
- Fitzpatrick, Richard
- Cano, Jaime González
- Green, Jonathan R
- Guzman, Hector M
- Hardenstine, Royale
- Hasan, Abdi
- Hazin, Fábio H V
- Hearn, Alex R
- Hueter, Robert E
- Jaidah, Mohammed Y
- Labaja, Jessica
- Ladino, Felipe
- Macena, Bruno C
- Morris Jr, John J
- Norman, Bradley M
- Peñaherrera-Palma, Cesar
- Pierce, Simon J
- Quintero, Lina M
- Ramírez-Macías, Dení
- Reynolds, Samantha D
- Richardson, Anthony J
- Robinson, David P
- Rohner, Christoph A
- Rowat, David R L
- Sheaves, Marcus
- Shivji, Mahmood S
- Sianipar, Abraham B
- Skomal, Gregory B
- Soler, German
- Syakurachman, Ismail
- Thorrold, Simon R
- Webb, D Harry
- Wetherbee, Bradley M
- White, Timothy D
- Clavelle, Tyler
- Kroodsma, David A
- Thums, Michele
- Ferreira, Luciana C
- Meekan, Mark G
- Arrowsmith, Lucy M
- Lester, Emily K
- Meyers, Megan M
- Peel, Lauren R
- Sequeira, Ana M M
- Eguíluz, Victor M
- Duarte, Carlos M
- Sims, David W
- Publication Date: 2022-5-9
Language
- English
Media Info
- Media Type: Digital/other
- Features: References;
- Pagination: e2117440119
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Serial:
- Proceedings of the National Academy of Sciences
- Volume: 119
- Issue Number: 20
- Publisher: National Academy of Sciences
- EISSN: 1091-6490
- Serial URL: http://www.pnas.org/
Subject/Index Terms
- TRT Terms: Conservation; Economic impacts; Endangered species; Fishes; High risk locations; Water traffic; Water transportation crashes
- Subject Areas: Environment; Marine Transportation; Planning and Forecasting; Safety and Human Factors;
Filing Info
- Accession Number: 01846414
- Record Type: Publication
- Files: TRIS
- Created Date: May 24 2022 10:07AM