Spatio-temporal genetic tagging of a cosmopolitan planktivorous shark provides insight to gene flow, temporal variation and site-specific re-encounters

Lieber, Lilian; Hall, Jackie; Berrow, Simon; Johnston, Emmett M.; Gubili, Chrysoula; Sarginson, Jane; Francis, Malcolm P.; Duffy, Clinton; Wintner, Sabine P.; Doherty, Philip D.; Godley, Brendan J.; Hawkes, Lucy A.; Witt, Matthew J.; Henderson, S. M.; Sabata, Eleonora de; Shivji, Mahmood S.; Dawson, Deborah A.; Sims, David; Jones, Catherine S.; Noble, Leslie R.

doi:10.1038/s41598-020-58086-4

Cited by 20 publications

(25 citation statements)

References 87 publications

(91 reference statements)

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“…The basking shark Cetorhinus maximus (Rus Hoelzel et al, 2006) and the megamouth shark Megachasma pelagios (Liu et al, 2018) are both characterized by a single, globally distributed population making both of these species less divergent than the whale shark. While recent research has suggested some level of genetic structure for the basking shark in the northeast Atlantic, a single panmictic population remains the prevailing view (Lieber et al, 2020). If correct, the single population model for both the basking and megamouth sharks suggests a clear difference in the recent dispersal patterns of the three planktivorous shark species.…”

Section: Discussionmentioning

confidence: 99%

Pieces in a global puzzle: Population genetics at two whale shark aggregations in the western Indian Ocean

Hardenstine

Cochran

et al. 2022

Ecology and Evolution

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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.

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Section: Discussionmentioning

confidence: 99%

Pieces in a global puzzle: Population genetics at two whale shark aggregations in the western Indian Ocean

Hardenstine

Cochran

et al. 2022

Ecology and Evolution

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“…More data on at-sea distribution of basking sharks is required to understand habitat use, threat overlap, and population status throughout the New Zealand and South Pacific region. The total South Pacific basking shark population size is unlikely to be high; in the Northeast Atlantic, basking shark numbers likely do not exceed 10 000 individuals (Lieber et al, 2020). With little population differentiation across global regions, it is plausible that basking sharks observed in New Zealand waters engage in large scale intra-and inter-oceanic migrations (Lieber et al, 2020).…”

Section: Future Directionsmentioning

confidence: 99%

“…The total South Pacific basking shark population size is unlikely to be high; in the Northeast Atlantic, basking shark numbers likely do not exceed 10 000 individuals (Lieber et al, 2020). With little population differentiation across global regions, it is plausible that basking sharks observed in New Zealand waters engage in large scale intra-and inter-oceanic migrations (Lieber et al, 2020). This may make species' detection more difficult in the vast marine space of New Zealand's EEZ.…”

Section: Future Directionsmentioning

confidence: 99%

“…The species also engages in long distance migrations and has been recorded crossing the Atlantic Ocean both from east to west and from north to south (Skomal et al, 2009;Braun et al, 2018;Dewar et al, 2018;Johnston et al, 2019). Recent genetic analysis suggests high gene flow and weak genetic structuring across the Atlantic and Pacific Oceans (Lieber et al, 2020). Despite their large size, basking sharks remain elusive and datapoor in the Pacific Ocean; habitat use and movement patterns in the South Pacific, and more specifically around New Zealand, are poorly understood.…”

Section: Introductionmentioning

confidence: 99%

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Drivers of Spatial Distributions of Basking Shark (Cetorhinus maximus) in the Southwest Pacific

Finucci

Duffy²,

Brough

et al. 2021

Front. Mar. Sci.

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Basking sharks (Cetorhinus maximus) were widely reported throughout New Zealand waters. Once commonly observed, and sometimes in large numbers, basking sharks are now infrequently reported. Basking shark observations are known to be highly variable across years, and their distribution and occurrence have been shown to be influenced by environmental predictors such as thermal fronts, chl-a concentration, and the abundance of prey (zooplankton). Little is known of basking sharks in the South Pacific and more information on distribution, habitat use, and migratory patterns is required to better understand the species’ regional ecology. Here, we used bootstrapped Habitat Suitability Models [HSM, ensembled from Boosted Regression Tree (BRT) and Random Forest (RF) models] to determine the drivers of basking shark distribution, predict habitat suitability and estimated uncertainty in the South Pacific for the first time. High−resolution environmental (1 km2 grid resolution) and biotic data, including inferred prey species, and all available basking shark records across New Zealand’s Exclusive Economic Zone (EEZ) were included in the ensemble HSMs. The most influential driver of modeled basking shark distribution was vertical flux of particulate organic matter at the seabed, which may indicate higher levels of primary production in the surface ocean and higher prey density in the mesopelagic zone and at the seafloor. The BRT and RF models had good predictive power (AUC and TSS > 0.7) and both models performed similarly with low variability in the model fit metrics. Areas of high basking shark habitat suitability included the east and west coasts of the South Island, Puysegur Ridge, and Auckland Island slope. The outputs produced here could be incorporated into future management framework for assessing threat and conservation needs (e.g., spatially explicit risk assessment) for this regionally protected species, as well as providing guidance for future research efforts (e.g., areas of interest for sampling).

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“…Owing to their life history (i.e., long lifespan, late maturity, and slow growth) and habitat use, sharks are exposed to pressure coming from different anthropogenic activities and therefore are subject to a higher risk of extinction if compared to other vertebrates (Lieber et al 2020). The main threats are represented by targeted harvesting (Li et al 2012;Cochran et al 2016;Perry et al 2018), bycatch, illegal fishing, habitat modification, vessel strikes (Speed et al 2008), and contaminant exposure (Boldrocchi et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Analysis of the temporal and spatial variability of whale shark (Rhincodon typus) aggregation in the South Ari Marine Protected Area, Maldives, Indian Ocean

Valsecchi

Lanfredi

Azzellino

et al. 2021

The European Zoological Journal

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Whale sharks are known to aggregate in coastal areas. In the South Ari Marine Protected Area (Maldives) a aggregation, mostly represented by young males with a high level of residency, has been described in the literature. Despite the worldwide interest in the natural resources of the Maldives, this population is increasingly subjected to anthropogenic pressure and major concern regards the flourishing tourist industry. In this study, data collected by the Maldives Whale Shark Research Programme between 2014 and 2017 have been used to detect both temporal and spatial patterns of occurrence. Favourable environmental conditions to visually detect whale sharks have been defined for the studied area. Accordingly, a total of 1077 shark encounters have been analysed in this study. Environmental conditions (i.e. sea surface temperature, monsoon occurrence) have been used to detect possible factors affecting the spatial and temporal variability of Rhincodon typus aggregations. A two-way ANOVA has been performed to detect temporal trends in animal occurrence, sea surface temperature pattern and to investigate the sea bottom depth variability during encounters. Significant differences in the monthly occurrence of whale sharks within the same year and among different years have been detected. Similar patterns have been observed for environmental parameters such as sea surface temperature and depth. A different spatial distribution has also been detected as a function of the Indian Monsoon reversal (north-eastern and south-western) affecting the area. During the northeast monsoon period, whale sharks appeared to concentrate in a smaller longitudinal range closer to the western-central part of the MPA, where deeper water conditions occur due to the proximity of a deep depression (submarine canyon). Results from this study provide new pieces of information for the implementation of dedicated management actions to protect the whale sharks population inhabiting the South Ari Marine Protected Area.

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Spatio-temporal genetic tagging of a cosmopolitan planktivorous shark provides insight to gene flow, temporal variation and site-specific re-encounters

Cited by 20 publications

References 87 publications

Pieces in a global puzzle: Population genetics at two whale shark aggregations in the western Indian Ocean

Pieces in a global puzzle: Population genetics at two whale shark aggregations in the western Indian Ocean

Drivers of Spatial Distributions of Basking Shark (Cetorhinus maximus) in the Southwest Pacific

Analysis of the temporal and spatial variability of whale shark (Rhincodon typus) aggregation in the South Ari Marine Protected Area, Maldives, Indian Ocean

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