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      Oceanic adults, coastal juveniles: tracking the habitat use of whale sharks off the Pacific coast of Mexico

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          Abstract

          Eight whale sharks tagged with pop-up satellite archival tags off the Gulf of California, Mexico, were tracked for periods of 14–134 days. Five of these sharks were adults, with four females visually assessed to be pregnant. At least for the periods they were tracked, juveniles remained in the Gulf of California while adults moved offshore into the eastern Pacific Ocean. We propose that parturition occurs in these offshore waters. Excluding two juveniles that remained in the shallow tagging area for the duration of tracking, all sharks spent 65 ± 20.7% (SD) of their time near the surface, even over deep water, often in association with frontal zones characterized by cool-water upwelling. While these six sharks all made dives into the meso- or bathypelagic zones, with two sharks reaching the maximum depth recordable by the tags (1285.8 m), time spent at these depths represented a small proportion of the overall tracks. Most deep dives (72.7%) took place during the day, particularly during the early morning and late afternoon. Pronounced habitat differences by ontogenetic stage suggest that adult whale sharks are less likely to frequent coastal waters after the onset of maturity.

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          Tracking apex marine predator movements in a dynamic ocean.

          Pelagic marine predators face unprecedented challenges and uncertain futures. Overexploitation and climate variability impact the abundance and distribution of top predators in ocean ecosystems. Improved understanding of ecological patterns, evolutionary constraints and ecosystem function is critical for preventing extinctions, loss of biodiversity and disruption of ecosystem services. Recent advances in electronic tagging techniques have provided the capacity to observe the movements and long-distance migrations of animals in relation to ocean processes across a range of ecological scales. Tagging of Pacific Predators, a field programme of the Census of Marine Life, deployed 4,306 tags on 23 species in the North Pacific Ocean, resulting in a tracking data set of unprecedented scale and species diversity that covers 265,386 tracking days from 2000 to 2009. Here we report migration pathways, link ocean features to multispecies hotspots and illustrate niche partitioning within and among congener guilds. Our results indicate that the California Current large marine ecosystem and the North Pacific transition zone attract and retain a diverse assemblage of marine vertebrates. Within the California Current large marine ecosystem, several predator guilds seasonally undertake north-south migrations that may be driven by oceanic processes, species-specific thermal tolerances and shifts in prey distributions. We identify critical habitats across multinational boundaries and show that top predators exploit their environment in predictable ways, providing the foundation for spatial management of large marine ecosystems. ©2011 Macmillan Publishers Limited. All rights reserved
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            Regression modelling strategies for improved prognostic prediction.

            Regression models such as the Cox proportional hazards model have had increasing use in modelling and estimating the prognosis of patients with a variety of diseases. Many applications involve a large number of variables to be modelled using a relatively small patient sample. Problems of overfitting and of identifying important covariates are exacerbated in analysing prognosis because the accuracy of a model is more a function of the number of events than of the sample size. We used a general index of predictive discrimination to measure the ability of a model developed on training samples of varying sizes to predict survival in an independent test sample of patients suspected of having coronary artery disease. We compared three methods of model fitting: (1) standard 'step-up' variable selection, (2) incomplete principal components regression, and (3) Cox model regression after developing clinical indices from variable clusters. We found regression using principal components to offer superior predictions in the test sample, whereas regression using indices offers easily interpretable models nearly as good as the principal components models. Standard variable selection has a number of deficiencies.
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              Travelling through a warming world: climate change and migratory species

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                Author and article information

                Contributors
                Journal
                PeerJ
                PeerJ
                peerj
                peerj
                PeerJ
                PeerJ Inc. (San Francisco, USA )
                2167-8359
                4 May 2017
                2017
                : 5
                : e3271
                Affiliations
                [1 ]Tiburón Ballena México, Conciencia México , La Paz, Mexico
                [2 ]Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, CIBIO/InBIO—Universidade do Porto , Porto, Portugal
                [3 ]The Laboratory, Marine Biological Association of the United Kingdom , Plymouth, United Kingdom
                [4 ]Marine Megafauna Foundation , Truckee, United States
                [5 ]Ocean and Earth Science, National Oceanography Centre Southampton, Waterfront Campus, University of Southampton , Southampton, United Kingdom
                [6 ]Center for Biological Sciences, Highfield Campus, University of Southampton , Southampton, United Kingdom
                [7 ]Independent Researcher , Zurich, Switzerland
                Article
                3271
                10.7717/peerj.3271
                5420197
                28484673
                83ae63a5-bf5b-4ce3-baa9-f6bfbb2fee59
                ©2017 Ramírez-Macías et al.

                This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited.

                History
                : 24 July 2015
                : 4 April 2017
                Funding
                Funded by: Save our Seas Foundation
                Funded by: Project Aware
                Funded by: Royal Geographical Society through (EXERCISE JURASSIC SHARK 2)
                Funded by: A1 scuba, downtown aquarium
                Funded by: Azul Marino Restaurant
                Funded by: Palapas Ventana
                Funded by: WWF-telcel
                Funded by: Cabo Expeditions
                Funded by: Shark Foundation and a private trust
                Funded by: Fundação para a Ciência e Tecnologia (FCT) Investigator Fellowship
                Award ID: IF/01611/2013
                Funded by: UK Natural Environment Research Council’s Oceans 2025 Strategic Research Programme (Theme 6 Science for Sustainable Marine Resources)
                Funded by: Marine Biological Association (MBA) Senior Research Fellowship
                This project was supported by Save our Seas Foundation, Project Aware, Royal Geographical Society through (EXERCISE JURASSIC SHARK 2), A1 scuba, downtown aquarium, Azul Marino Restaurant, Palapas Ventana, WWF-telcel and Cabo Expeditions. SJP’s involvement in this study was supported by the GLC Charitable Trust, the Shark Foundation and a private trust. NQ was funded through a Fundação para a Ciência e Tecnologia (FCT) Investigator Fellowship (ref.: IF/01611/2013). Funding for NH was provided by the UK Natural Environment Research Council’s Oceans 2025 Strategic Research Programme (Theme 6 Science for Sustainable Marine Resources) in which DWS was a principal investigator. DWS was also supported by a Marine Biological Association (MBA) Senior Research Fellowship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
                Categories
                Animal Behavior
                Conservation Biology
                Marine Biology

                movements,habitat use,diving behavior,size segregation,whale sharks,pacific coast of mexico,habitat conservation

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