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  1. Article ; Online: Toward the quantification of a conceptual framework for movement ecology using circular statistical modeling.

    Ichiro Ken Shimatani / Ken Yoda / Nobuhiro Katsumata / Katsufumi Sato

    PLoS ONE, Vol 7, Iss 11, p e

    2012  Volume 50309

    Abstract: To analyze an animal's movement trajectory, a basic model is required that satisfies the following conditions: the model must have an ecological basis and the parameters used in the model must have ecological interpretations, a broad range of movement ... ...

    Abstract To analyze an animal's movement trajectory, a basic model is required that satisfies the following conditions: the model must have an ecological basis and the parameters used in the model must have ecological interpretations, a broad range of movement patterns can be explained by that model, and equations and probability distributions in the model should be mathematically tractable. Random walk models used in previous studies do not necessarily satisfy these requirements, partly because movement trajectories are often more oriented or tortuous than expected from the models. By improving the modeling for turning angles, this study aims to propose a basic movement model. On the basis of the recently developed circular auto-regressive model, we introduced a new movement model and extended its applicability to capture the asymmetric effects of external factors such as wind. The model was applied to GPS trajectories of a seabird (Calonectris leucomelas) to demonstrate its applicability to various movement patterns and to explain how the model parameters are ecologically interpreted under a general conceptual framework for movement ecology. Although it is based on a simple extension of a generalized linear model to circular variables, the proposed model enables us to evaluate the effects of external factors on movement separately from the animal's internal state. For example, maximum likelihood estimates and model selection suggested that in one homing flight section, the seabird intended to fly toward the island, but misjudged its navigation and was driven off-course by strong winds, while in the subsequent flight section, the seabird reset the focal direction, navigated the flight under strong wind conditions, and succeeded in approaching the island.
    Keywords Medicine ; R ; Science ; Q
    Subject code 612
    Language English
    Publishing date 2012-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article: Comparison of the effectiveness of paired and single tori lines for preventing bait attacks by seabirds and their bycatch in pelagic longline fisheries

    Sato, Noriyosi / Daisuke Ochi / Hiroshi Minami / Kotaro Yokawa / Nobuhiro Katsumata

    Fisheries research. 2013 Feb., v. 140

    2013  

    Abstract: To examine the effectiveness of the paired tori lines (PT) for reducing seabird bycatch in pelagic longline fisheries, bait attack behaviors during PT deployment was compared with that during single tori line (ST) deployment. Detailed observations of ... ...

    Abstract To examine the effectiveness of the paired tori lines (PT) for reducing seabird bycatch in pelagic longline fisheries, bait attack behaviors during PT deployment was compared with that during single tori line (ST) deployment. Detailed observations of seabird species abundance and attacks on baits were conducted from a longliner operating in the western North Pacific from December 2010 to January 2011. Line settings alternated between ST and PT deployments. About 90% of the seabirds attending the vessel were Laysan albatrosses (Phoebastria immutabilis), and most attacks were by this species. Attacks occurred across broad areas from 25 to 200m of the stern during ST deployments, whereas PT deployment resulted in few attacks within 75m of the stern. The number of secondary attacks (birds charging for the bait brought to the surface by the bird making the primary attack) was significantly lower during PT than during ST deployment. These results suggest that PT performed better than ST in reducing bait attacks, and consequently seabird mortality.
    Keywords baits ; bycatch ; mortality ; seabirds
    Language English
    Dates of publication 2013-02
    Size p. 14-19.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 406532-3
    ISSN 0165-7836
    ISSN 0165-7836
    DOI 10.1016/j.fishres.2012.11.007
    Database NAL-Catalogue (AGRICOLA)

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  3. Article: Distribution, body length, and abundance of blue shark and shortfin mako offshore of northeastern Japan, as determined from observed pelagic longline data, 2000–2014

    Ohshimo, Seiji / Daisuke Ochi / Hiroaki Matsunaga / Hiroshi Minami / Ko Shiozaki / Kotaro Yokawa / Masashi Kiyota / Mikihiko Kai / Nobuhiro Katsumata / Yasuko Semba / Yuki Fujinami

    Fisheries oceanography. 2016 May, v. 25, no. 3

    2016  

    Abstract: Longline surveys have been conducted in the Northwest Pacific Ocean from 2000 to 2014 using chartered commercial longline vessels. Each year, two cruises were conducted offshore of northeastern Japan from mid‐April to mid‐June. For each longline set ... ...

    Abstract Longline surveys have been conducted in the Northwest Pacific Ocean from 2000 to 2014 using chartered commercial longline vessels. Each year, two cruises were conducted offshore of northeastern Japan from mid‐April to mid‐June. For each longline set during the surveys, onboard scientists collected detailed biological information about the species caught, such as the size and sex, and recorded the catch numbers for all species. Blue shark (Prionace glauca) and shortfin mako (Isurus oxyrinchus) have eurythermal distributions, but the application of a generalized additive model (GAM) showed that the sea surface temperatures (SSTs) at catch sites positive for shortfin mako were warmer than those for blue shark. On the basis of the GAM, the probabilities of occurrence of both sharks differed by size category: small sharks had a narrower SST range than that of large sharks. Most catches of both sharks were juveniles, and the nominal catch rate of blue shark was more than 10 times that of shortfin mako. The standardized catch per unit effort (CPUE) for both species was calculated using a generalized linear model (GLM) with negative binomial errors, or a delta‐lognormal GLM. The standardized CPUE for blue shark in the second quarter of the year peaked in the mid‐2000s and then decreased, but it has been increasing since 2012. The CPUE for shortfin mako in the second quarter generally increased, with fluctuations.
    Keywords body length ; Isurus oxyrinchus ; juveniles ; linear models ; Prionace glauca ; sharks ; surface temperature ; surveys ; Japan ; Pacific Ocean
    Language English
    Dates of publication 2016-05
    Size p. 259-276.
    Publishing place Blackwell Science
    Document type Article
    ZDB-ID 1214985-8
    ISSN 1054-6006 ; 1361-9470
    ISSN 1054-6006 ; 1361-9470
    DOI 10.1111/fog.12149
    Database NAL-Catalogue (AGRICOLA)

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  4. Article ; Online: Scaling of soaring seabirds and implications for flight abilities of giant pterosaurs.

    Katsufumi Sato / Kentaro Q Sakamoto / Yutaka Watanuki / Akinori Takahashi / Nobuhiro Katsumata / Charles-André Bost / Henri Weimerskirch

    PLoS ONE, Vol 4, Iss 4, p e

    2009  Volume 5400

    Abstract: The flight ability of animals is restricted by the scaling effects imposed by physical and physiological factors. In comparisons of the power available from muscle and the mechanical power required to fly, it is predicted that the margin between the ... ...

    Abstract The flight ability of animals is restricted by the scaling effects imposed by physical and physiological factors. In comparisons of the power available from muscle and the mechanical power required to fly, it is predicted that the margin between the powers should decrease with body size and that flying animals have a maximum body size. However, predicting the absolute value of this upper limit has proven difficult because wing morphology and flight styles varies among species. Albatrosses and petrels have long, narrow, aerodynamically efficient wings and are considered soaring birds. Here, using animal-borne accelerometers, we show that soaring seabirds have two modes of flapping frequencies under natural conditions: vigorous flapping during takeoff and sporadic flapping during cruising flight. In these species, high and low flapping frequencies were found to scale with body mass (mass(-0.30) and mass(-0.18)) in a manner similar to the predictions from biomechanical flight models (mass(-1/3) and mass(-1/6)). These scaling relationships predicted that the maximum limits on the body size of soaring animals are a body mass of 41 kg and a wingspan of 5.1 m. Albatross-like animals larger than the limit will not be able to flap fast enough to stay aloft under unfavourable wind conditions. Our result therefore casts doubt on the flying ability of large, extinct pterosaurs. The largest extant soarer, the wandering albatross, weighs about 12 kg, which might be a pragmatic limit to maintain a safety margin for sustainable flight and to survive in a variable environment.
    Keywords Medicine ; R ; Science ; Q
    Subject code 590
    Language English
    Publishing date 2009-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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