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Identifying foraging events in deep diving southern elephant seals, Mirounga leonina, using acceleration data loggers

journal contribution
posted on 2023-05-17, 22:26 authored by Gallon, S, Bailleaul, F, Charrassin, JB, Guinet, C, Bost, CA, Handrich, Y, Mark HindellMark Hindell
Southernelephantseals(Miroungaleonina) rangewidelythroughouttheSouthernOceanandare associatedwithimportanthabitats(e.g., iceedges,shelf)wheretheyaccumulateenergytofueltheir reproductiveeffortsonland.Knowledgeofthefinescaleforagingbehaviourusedtogarnerthisenergy, however,islimited.Forthefirsttime,accelerationloggersweredeployedonthreeadultsouthern elephantsealsduringatranslocationstudyatKerguelenIsland.Theaimsofthestudywereto (1) identifypreycaptureattemptsusing2-Daccelerometertagsdeployedontheheadofsouthern elephantseals,(2)comparethenumberofforagingdivesidentifiedbysimpledivedepthprofilesand accelerometerprofilesand(3)comparedivecharacteristicsbetweenpreyencounterandnon-prey encounterdives.The2-Dloggersrecordeddeptheverysecond,surgeandheaveaccelerationsat8or 16 Hzandwerecarriedforperiodsbetween23and121h.Rapidheadmovementswereinterpretedto be associatedwithpreyencounterevents.Accelerationdatadetectedpossiblepreyencountereventsin 39–52%ofdiveswhilst67–80%ofdiveswereclassifiedasforagingdiveswhenusingdivedepthprofiles alone. Preyencountersoccurredinsuccessivedivesduringdaysandnightsandlastedbetweentenths of asecondand7.6min.Binomiallinearmixedeffectmodelsshowedthatsealswerediving significantlydeeperandincreasedbothdescentrateandbottomdurationwhenencounteringprey. Dive duration,however,didnotsignificantlyincreaseduringdiveswithpreyencounters.Theseresults are inaccordancewithoptimalforagingtheory,whichpredictsthatdeepdiversshouldincreaseboth their transitratesandthetimespentatdepthwhenaprofitablepreypatchisencountered.These findings indicatethatthistechniqueispromisingasitmoreaccuratelydetectspossiblepreyencounter eventscomparedwithdivedepthprofilesaloneandthusprovidesabetterunderstandingofseal foragingstrategies.

Funding

Australian Research Council

History

Publication title

Deep-Sea Research. Part 2: Topical Studies in Oceanography

Volume

88-89

Pagination

14-22

ISSN

0967-0645

Department/School

Institute for Marine and Antarctic Studies

Publisher

Pergamon-Elsevier Science Ltd

Place of publication

The Boulevard, Langford Lane, Kidlington, Oxford, England, Ox5 1Gb

Rights statement

Copyright 2012 Elsevier Ltd.

Repository Status

  • Restricted

Socio-economic Objectives

Assessment and management of coastal and estuarine ecosystems

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