Pierce Simon J.

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Simon J.

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  • Article
    Pieces in a global puzzle: population genetics at two whale shark aggregations in the western Indian Ocean
    (Wiley Open Access, 2022-01-25) Hardenstine, Royale S. ; He, Song ; Cochran, Jesse E. M. ; Braun, Camrin D. ; Cagua, E. Fernando ; Pierce, Simon J. ; Prebble, Clare E. M. ; Rohner, Christoph A. ; Saenz-Agudelo, Pablo ; Sinclair-Taylor, Tane H. ; Skomal, Gregory B. ; Thorrold, Simon R. ; Watts, Alexandra M. ; Zakroff, Casey ; Berumen, Michael L.
    The whale shark Rhincodon typus is found throughout the world's tropical and warm-temperate ocean basins. Despite their broad physical distribution, research on the species has been concentrated at a few aggregation sites. Comparing DNA sequences from sharks at different sites can provide a demographically neutral understanding of the whale shark's global ecology. Here, we created genetic profiles for 84 whale sharks from the Saudi Arabian Red Sea and 72 individuals from the coast of Tanzania using a combination of microsatellite and mitochondrial sequences. These two sites, separated by approximately 4500 km (shortest over-water distance), exhibit markedly different population demographics and behavioral ecologies. Eleven microsatellite DNA markers revealed that the two aggregation sites have similar levels of allelic richness and appear to be derived from the same source population. We sequenced the mitochondrial control region to produce multiple global haplotype networks (based on different alignment methodologies) that were broadly similar to each other in terms of population structure but suggested different demographic histories. Data from both microsatellite and mitochondrial markers demonstrated the stability of genetic diversity within the Saudi Arabian aggregation site throughout the sampling period. These results contrast previously measured declines in diversity at Ningaloo Reef, Western Australia. Mapping the geographic distribution of whale shark lineages provides insight into the species’ connectivity and can be used to direct management efforts at both local and global scales. Similarly, understanding historical fluctuations in whale shark abundance provides a baseline by which to assess current trends. Continued development of new sequencing methods and the incorporation of genomic data could lead to considerable advances in the scientific understanding of whale shark population ecology and corresponding improvements to conservation policy.
  • Article
    Global collision-risk hotspots of marine traffic and the world’s largest fish, the whale shark
    (National Academy of Sciences, 2022-05-17) 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. ; Bessudo Lion, Sandra ; 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 ; Gonzalez Cano, Jaime ; Green, Jonathan R. ; Guzman, Hector M. ; Hardenstine, Royale ; Hasan, Abdi ; Hazin, Fabio H. V. ; Hearn, Alex R. ; Hueter, Robert ; Jaidah, Mohammed Y. ; Labaja, Jessica ; Ladino, Felipe ; Macena, Bruno C. L. ; Morris, John J. Jr. ; Norman, Bradley M. ; Penaherrera-Palma, Cesar ; Pierce, Simon J. ; Quintero, Lina M. ; Ramirez-Macias, Deni ; Reynolds, Samantha D. ; Richardson, Anthony J. ; Robinson, David P. ; Rohner, Christoph A. ; Rowat, David R. L. ; Sheaves, Marcus ; Shivji, Mahmood ; 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. ; Eguiluz, Victor M. ; Duarte, Carlos M. ; Sims, David W.
    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.