It is not just size that matters shark cruising s

Authors: Laura A Ryan Jessica J Meeuwig Jan M Hemmi Shaun P Collin Nathan S Hart

Publish Date: 2015/05/05

Volume: 162, Issue: 6, Pages: 1307-1318

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Abstract

Speed of locomotion plays an important role in an animal’s biology and ecology and is of particular interest in aquatic animals Determining cruising speeds of shark—for which such data are scarce—may help to better understand their interactions with prey the size of the home ranges they maintain their energetic costs and how they interact with their environment through sensory perception In this study the cruising speeds of a range of different shark species were measured using stereobaited remote underwater video systems stereoBRUVS The relationship between cruising speeds and fork length species order habitat trophic level temperature and tail shape was then modelled Fork length and species best explained the cruising speeds of the eight species of shark studied Carcharhinus amblyrhynchos Carcharhinus albimarginatus Carcharhinus obscurus Furgaleus macki Carcharhinus obesus Mustelus antarcticus Heterodontus portusjacksoni and Parascyllium variolatum This linear model had a slope that did not differ statistically from that of the theoretical model proposed by Weihs Scale effects in animal locomotion Academic Press New York pp 333–338 1977 which suggests that the relationship between cruising speed and length appears to be dominated by energetics The results suggest that existing allometric estimates of cruising speeds can be improved by defining cruising speeds for each species as a function of length Currently literature presents cruising speed data for only a few species of shark therefore we provide a second generalised model which predicts cruising speed as a function of length and tail shape The length + tail shape model was selected based on its generality and accuracy in estimating shark cruising speeds obtained from acoustic tags This length + tail shape model was significantly better than a length only model it explained a further 76  of the variation in cruising speed derived from stereoBRUVS and acoustic tagging data than a length only model The more accurate prediction of the length + tail shape model is most likely because tail shape is correlated with a number of ecological factorsWe would like to acknowledge the financial support of the Western Australia’s State Government to NSH and SPC Collection of footage was supported by various grants including funding from Australia’s National Heritage Trust and the Zoological Society of London to JJM LAR was supported by an Australian Postgraduate Award JH was supported by an Australian Research Council Future Fellowship JMM acknowledges the intellectual contribution of Robert Henry Peters deceased on the importance of allometry

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