Dataset Information

World without borders-genetic population structure of a highly migratory marine predator, the blue shark (Prionace glauca).

ABSTRACT: Highly migratory, cosmopolitan oceanic sharks often exhibit complex movement patterns influenced by ontogeny, reproduction, and feeding. These elusive species are particularly challenging to population genetic studies, as representative samples suitable for inferring genetic structure are difficult to obtain. Our study provides insights into the genetic population structure one of the most abundant and wide-ranging oceanic shark species, the blue shark Prionace glauca, by sampling the least mobile component of the populations, i.e., young-of-year and small juveniles (<2 year; N = 348 individuals), at three reported nursery areas, namely, western Iberia, Azores, and South Africa. Samples were collected in two different time periods (2002-2008 and 2012-2015) and were screened at 12 nuclear microsatellites and at a 899-bp fragment of the mitochondrial control region. Our results show temporally stable genetic homogeneity among the three Atlantic nurseries at both nuclear and mitochondrial markers, suggesting basin-wide panmixia. In addition, comparison of mtDNA CR sequences from Atlantic and Indo-Pacific locations also indicated genetic homogeneity and unrestricted female-mediated gene flow between ocean basins. These results are discussed in light of the species' life history and ecology, but suggest that blue shark populations may be connected by gene flow at the global scale. The implications of the present findings to the management of this important fisheries resource are also discussed.

SUBMITTER: Verissimo A

PROVIDER: S-EPMC5496551 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature

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Publications

World without borders-genetic population structure of a highly migratory marine predator, the blue shark (<i>Prionace glauca</i>).

Veríssimo Ana A Sampaio Íris Í McDowell Jan R JR Alexandrino Paulo P Mucientes Gonzalo G Queiroz Nuno N da Silva Charlene C Jones Catherine S CS Noble Leslie R LR

Ecology and evolution 20170524 13

Highly migratory, cosmopolitan oceanic sharks often exhibit complex movement patterns influenced by ontogeny, reproduction, and feeding. These elusive species are particularly challenging to population genetic studies, as representative samples suitable for inferring genetic structure are difficult to obtain. Our study provides insights into the genetic population structure one of the most abundant and wide-ranging oceanic shark species, the blue shark <i>Prionace glauca,</i> by sampling the lea ...[more]

PMID: 28690806

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Project description:Spatial structuring and segregation by sex and size is considered to be an intrinsic attribute of shark populations. These spatial patterns remain poorly understood, particularly for oceanic species such as blue shark (Prionace glauca), despite its importance for the management and conservation of this highly migratory species. This study presents the results of a long-term electronic tagging experiment to investigate the migratory patterns of blue shark, to elucidate how these patterns change across its life history and to assess the existence of a nursery area in the central North Atlantic. Blue sharks belonging to different life stages (n = 34) were tracked for periods up to 952 days during which they moved extensively (up to an estimated 28.139 km), occupying large parts of the oceanic basin. Notwithstanding a large individual variability, there were pronounced differences in movements and space use across the species' life history. The study provides strong evidence for the existence of a discrete central North Atlantic nursery, where juveniles can reside for up to at least 2 years. In contrast with previously described nurseries of coastal and semi-pelagic sharks, this oceanic nursery is comparatively vast and open suggesting that shelter from predators is not its main function. Subsequently, male and female blue sharks spatially segregate. Females engage in seasonal latitudinal migrations until approaching maturity, when they undergo an ontogenic habitat shift towards tropical latitudes. In contrast, juvenile males generally expanded their range southward and apparently displayed a higher degree of behavioural polymorphism. These results provide important insights into the spatial ecology of pelagic sharks, with implications for the sustainable management of this heavily exploited shark, especially in the central North Atlantic where the presence of a nursery and the seasonal overlap and alternation of different life stages coincides with a high fishing mortality.

Project description:There is worldwide concern about the status of elasmobranchs, primarily as a result of overfishing and bycatch with subsequent ecosystem effects following the removal of top predators. Whilst abundant and wide-ranging, blue sharks (Prionace glauca) are the most heavily exploited shark species having suffered marked declines over the past decades, and there is a call for robust abundance estimates. In this study, we utilized depth data collected from two blue sharks using pop-up satellite archival tags, and modelled the proportion of time the sharks were swimming in the top 1-meter layer and could therefore be detected by observers conducting aerial surveys. The availability models indicated that the tagged sharks preferred surface waters whilst swimming over the continental shelf and during daytime, with a model-predicted average proportion of time spent at the surface of 0.633 (SD = 0.094) for on-shelf, and 0.136 (SD = 0.075) for off-shelf. These predicted values were then used to account for availability bias in abundance estimates for the species over a large area in the Northeast Atlantic, derived through distance sampling using aerial survey data collected in 2015 and 2016 and modelled with density surface models. Further, we compared abundance estimates corrected with model-predicted availability to uncorrected estimates and to estimates that incorporated the average time the sharks were available for detection. The mean abundance (number of individuals) corrected with modelled availability was 15,320 (CV = 0.28) in 2015 and 11,001 (CV = 0.27) in 2016. Depending on the year, these estimates were ~7 times higher compared to estimates without the bias correction, and ~3 times higher compared to the abundances corrected with average availability. When the survey area contains habitat heterogeneity that may affect surfacing patterns of animals, modelling animals' availability provides a robust alternative to correcting for availability bias and highlights the need for caution when applying "average" correction factors.

Project description:One of the mandates of the International Union of Immunological Societies (IUIS) is to promote immunological education to young scientists across the globe, including a large focus on those from low and low-to-middle income countries (LIC and LMIC). It strives to achieve this goal through the Education Committee (EDU), which is one of ten committees of the IUIS. To this end, EDU organizes three to four one-week courses per year in close cooperation with regional immunological societies and local organizers. Initially, the focus has been on Africa, addressing the most relevant topics and health issues facing specific countries or regions in the continent. The idea was then extended to Latin America and now also includes courses in Asia. The faculty of all courses is a blend of international and local/regional experts also known for their teaching expertise. The courses are highly interactive, and include "meet-the-speakers" sessions, poster walks, and sessions on grant or PhD project writing, and on practical aspects of becoming a successful scientist. Importantly, all the IUIS-EDU courses use a combination of pre- and during-course on-line learning followed by consolidation of knowledge in a collegial setting. This "flipped" classroom approach ensures that participants have acquired the basic knowledge needed to optimize their participation in the course. Immunopaedia is the IUIS-endorsed immunology learning site used for this purpose. All faculty members are requested to contribute material related to their specific topic while students must learn the on-line material before coming in person to the course. All course participants have free access to all Immunopaedia material indefinitely. The implementation of regional immunology courses targeted to local health issues in areas of the world where PhD students, post-doctoral, and early career scientists often do not have access to open on-line resources and contact with renowned experts in the field has proven to be highly successful. The long-term impact of this structured educational program is already visible through the large number of young scientists who are now connected via Immunopaedia and who are forming networks in regions where there had been very little contact before and building new Immunological Societies.

Dataset Information

World without borders-genetic population structure of a highly migratory marine predator, the blue shark (Prionace glauca).

Publications

World without borders-genetic population structure of a highly migratory marine predator, the blue shark (<i>Prionace glauca</i>).

Similar Datasets

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