December 2019 BBC Wildlife 77WHALES AND DOLPHINS
Thisis quitecostly,though,as
researchershavetofollowthe
signal(andthusthewhale)
atsea,andthetransmitter
onlyworkswhenit is above
thesurface(whenthe
whalecomesuptobreathe)
and,evenunderideal
conditions,is limitedin
rangetoline-of-sight.
A farmoreusefuladvance
is thesatellitetransmitter.This
beamssignalsuptoorbiting
satellitesandfromthereback
toreceivingstationsanywhere
onEarth.Thegreatadvantages
ofa satellitetransmitterarethat
thereis noneedforresearchersto
followthewhaleinthefieldandit
enablesthemtostudyindividuals
inthemostremotepartsofthe
worldandmostchallenging
conditions.Again,thereare
limitations:it onlyworkswhen
thewhalesurfacestobreathe,the
signalsarenotinrealtime(they
maybeseveralhoursold),andit
requires a lot of energy.Withcurrentbatterytechnology,thiscan
bequitelimiting.
Whales,dolphinsandporpoisesliveina
worldthatis dominatedbysound,whichthey
usetocommunicate,navigateandfindfood,
anda greatdealcanbelearnedbylistening
tothemunderwater.Thisis anincredibly
challengingareaofresearch– it hasbeen
likenedtotryingtofindoutwhatgoeson
inNewYorkbydanglinga microphone
fromthetopoftheEmpireStateBuilding- butexperiencedwhalescientistsusing
sophisticatedunderwatermicrophones,
calledhydrophones,havebeenmaking
someexcitingdiscoveriesinrecentyears.
Meanwhile,theadventofminiaturevideo
cameras,capableofrecordinginsurprisingly
lowlightconditions,is openingupa whole
newworldofcetology.Researchersare
beginningtousethese‘crittercams’tosee
whatwhales,dolphinsandporpoisesare
doingunderwater.Makingobservationslike
thisis anareaofresearchthatland-based
biologistsstudyingterrestrialmammalshave
alwaystakenforgranted.
Therearestillnoshortcutsinwhale
research.Studyingsuchelusivecreaturesis
all about being content with tiny snippets
forprofessionalresearcherstospendlong
periodsoftimeat sea,sotheyoftenrelyon
touriststoprovidephotographsfortheir
catalogues.A greatmanyofthephotographs
inthehumpbackwhaleandkillerwhale
cataloguesfortheAntarctic,forexample,
havebeentakenbytouristsonpolarcruises.
Aswellaslookingat whales’outward
attributes,scientistsarekeentoexamine
theirancestralhistory.Dodifferentcalves
withthesamemothersharethesamefather?
Areindividualsthatspenda lotoftime
togetherrelated?Theseandmanyother
intriguingquestionscanbeansweredjust
byexamininga tissuesample,suchasa
smallpieceofa whale’ssloughedskin.More
accurately,it is thegeneticmaterial,orDNA,
inthesamplethatis sorevealing,because
notwoanimalshaveexactlythesameDNA
(yetrelatedanimalsshowvaryingdegrees
ofsimilarity).Thecleverdetectivework
involvedininterpretingthisinformation
is called‘DNAfingerprinting’.Keepingtrack
Muchcanalsobelearnedbyusing
technologytotrackmarinemammals.It is
possibletoattacha speciallydesignedtag to
a whale,dolphinorporpoise,which
gathersdataandeitherrecords
it forlaterretrieval(ithasto
befound– andrecovered- inordertogetthestored
information)ortransmitsit
toa specialreceiver.Thisis
knownas‘telemetry’.
Sometransmittersare
merelytrackingdevices - providinglittlemore
informationthantheanimal’s
geographicalposition–
buteventhesehavefilled
enormousgapsinour
knowledgeovertheyears.
However,moresophisticated
modelscanprovideinformation
suchasa whale’sswimming
speed,thedepthandangleof
itsdives,itsskintemperature
andthetemperatureofthe
surroundingwater,itsheartrate,
anysoundsit mayproduce,light
levels,andmuchmorebesides.
Thesimplestformoftransmitter - a radiotransmitter– broadcasts
a radiosignalthatcanbereceived
Southern right whale: Hiroya Minakuchi/Minden/FLPA; aerial: NOAA Fisheries/Christin Khan/MMPA permit 17355; flippers: Martin Camm; dive sequence & blow: Rebecca Robinsonby an antenna in real time.