BBC Wildlife - UK 2020-07)

(Antfer) #1
Right:swimmingwithsharks.
Below:transmitterswereused
byresearchersfromExeter
Universityin 2007 toattachto
baskingsharksotheIsland
of Coll in the Inner Hebrides.

ISLAHODGSONis a conservation
scientistandguideforBasking
SharkScotland– visitthe
websiteatbaskingsharkscotland.co.uk

FINDOUTMOREDiscovermore
aboutbaskingsharksonourwebsite:
discoverwildlife.com/basking-sharks

behaviourtoconveyinformation.Possibly,
it couldbea signaltoothersharksinthe
areathattheyareavailableformating,or
a displayofdominancebymales.Other
observationsfromDonegalinIrelandseem
tosuggestbreachingis potentiallystimulated
byenvironmentalfactors,suchasseasurface
temperature.Certainly,moreresearchis
neededtostudythisbehaviourinrelation to
sexandotherpotential triggers.

Babyshark
Anothersecretis where,andhow,basking
sharksgivebirth.Fromverylimited
evidence,it appearstheyareovoviviparous,
meaningthatthenew-bornpupbreaksout
oftheeggwhilestillinsidethemother,and
is effectivelybornalreadyhatched.
Theonlyexistingeye-witnessaccount
ofpuppingcomesfromtwoNorwegian
fishermen,HansGoksoyrandJonas
Sordal,in1936.Baskingsharkswere
onceextensivelyhuntedfortheirlarge
andoilyliver– usedinlamps,cosmetics,
andlubricants.Largefisheriesexistedin
Scotland,IrelandandScandinavia,and
exploitationalmostdrovethespeciesto
thebrinkofextinction.
Whiletowinga harpoonedsharkbackto
thefishery,theNorwegianfarmersdescribed
a livesharkbeingbirthedandswimming
away,closelyfollowedbyfourothers,with
oneotherdeadinsidethemother.This
tinysnippetofinformationimpliesthat
baskingsharkshavelittersofuptosixand
arepossiblyK-selected– investingmorein
smaller, but more developed, young. Juvenile

Satellitetransmitters
areattachedtothe
sharks via a pole.

sharkshavebeensighted– conspicuous
fortheirmorepronounced,twistednoses,
whichstraightenoutovertime– however,
theirentranceintothisworldis yettobe
scientificallyrecorded.
Learningmoreaboutthismysterious
speciesis vitaltoitsprotection.
Distinguishingbreeding,matingand
feedingsitescanhelpusidentifypotential
overlap with human activities, informing

protectivemeasuresintheseareas.The
denseaggregationsweobservearound
CollandTiree– aswellasthepossible
matingactivity– suggestthatthisis a
highlyimportantareaforthespecies.A
MarineProtectedArea(MPA)hasbeen
proposedfortheHebrides,toprotectthe
baskingsharkandothermobilespecies
thatdependonthesewaters,suchasminke
whalesandRisso’sdolphins.ThoughMPA
designationsarechallenging– especiallyfor
migratoryspecies– thiscouldprovidevital
safeguardingforanareakeytothebasking
shark’ssurvival.
Backinthegentlyundulatingwatersof
theAtlantic,wewatchthesharkswimpast,
socloseyoucanlookherintheeye.Forone
sobig,shemoveswitheasethroughthe
water,hersizealmosttoomuchforthe
humanbraintocomprehend.Thegirlnext
tomegrabsmyarmandsqueezesit tight.
I turntoseeherbeamingfaceandslightly
fogged-upmask;theothersoverher
shoulderlookjustasexhilarated.The
encounterwasjusta fewseconds,but
nothingcomparestoa 9mshark just
casually passing youby.

July 2020 BBC Wildlife 45

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