70 | July⢠2018
SWIMMING WITH SHARKS
hunting habits he says. Tiger sharks
rely on surprise to catch their prey.
âIfyouârepredictableyourpreyis
goingtoadapttothatpredictability.
It makes sense to suddenly appear in
an area and not be there very long.â
Theuptickinattacksintheau-
tumn might also be due to having
more sharks around the islands at
thattimeofyear.Thatâswhentiger
sharks come in to give birth Meyer
pointsout.Femaletigersharksmake
a huge energ y investment when they
ovulate.Theireggsarethesizeof
baseballsandtheycanhave80pups
inalitter.hatmightmeanthatfe-
male sharks reach the island hungry
andneedingtoreplaceenergyre-
serves after giving birth.
Another possible theory involves
a proliferation of sea turtles. Aft-
er decades of intense exploitation
green sea turtles received protection
in 1978. Theyâre now common offOur group even had a scare
when an angelish wandered
intoourmidstandthereef
sharks and lemon sharks went
intoafrenzychasingitasit
hid between peopleâs legs.
Everyone thought someone
was going to be bitten in the
melee and there were three
450-kilogram tiger sharks
millingaroundthatmight
suddenly have taken an inter-
estinawoundeddiver.
We were back in t he water
thenextdaybutitwasthe
kind of fluke that reminds you that
sharksarewildandinherentlyun-
predictable. And according to sci-
entists who study them tigers are
especially unpredictable.
IFLEWTOOAHUto meet Carl Meyer
attheUniversityofHawaiitodiscuss
hisresearchontherecentspikeinti-
gersharkattacksinHawaii-which
havejumpedfromanaverageofjust
overfourayearfrom2000to2011to
morethantenayearin20122013
and2016.Meyerandhisteamhave
tagged hundreds of tiger sharks with
satellitetagsandacoustictracking
devices.Hesaystheyârejustbegin-
ning to understand them.
âTigersharkscanshowupany
timeofdayornightandtheymaybe
thereonedayandbackthenextday
orgoneforthreeyearsâhesays.
At least some of this unpredict-
ability is likely caused by the sharksâ PHOTO: NATIONAL GEOGRAPHIC
Anewbornpuphasthestripedmarkingsalong
itsmetre-longbodythatgivethetigersharkits
name. he markings fade as the shark grows