Stocks would
recover, but
not all of them
Recentyearshaveseensingle-useplastics
demonisedasthepublichaswokenuptothe
e ectsofmarineplastics.Butfewpeople
realisethecontributionthatfishingmakes.
Lostfishinggearaccountsforabout 10 per
centofallmarineli erand,accordingtoa
2018 study, 86 percentofthebigpiecesof
plastic oatinginthe‘GreatPacificGarbage
Patch’.Withoutfishing,we’dalsowipeout
pollutionandemissionsfromfishingboats
(one 2014 studyclaimedthatlobsterswere
themostfuel-intensivespecies,withsome
boatsusing20,000litresoffueltocatcha
singletonne).However,aquaculturecould
bringothersourcesofpollution,suchasfeed
andchemicalproductsthatareusedtocontrol
disease.Thesepollutantsentertheseawhere
fisharefarmedinpensandcages.Francosays
thataquacultureis,atleastinsomesectors,
lesspollutingthanit was.“Considersalmon
farmingintheUK– antibioticshavenotbeen
routinelyusedinyears,”shesays.“But
regulationsandconditionscanbevery
di erentindi erentsectorsandcountries.”
Nevertheless,aquaculturegloballywillhave
tobecomemoresustainableif thefarmers
wanttoaccessthemostvaluablemarkets,as
thesedemandhigherstandards.
A furtherconcernis thatpushingseafood
productiononshoreintohigh-techsystems
likerecirculatingtankswouldtakespace
fromotherfoodproductionindustries.One
space-savingsolutioncouldbeanintegrated,
‘multitrophic’system,growingfish,bivalves
likemussels,andseaweedaltogether.Gentry
reckonsthatanythinginvolvingseaweedis
“fabulous”,astheplantsextractpollutants
from the water, helping to purify it.Temporarybansonfishingof
certainspeciesarealreadyused
worldwidetomaintainfishstocks
andprotecttheenvironment.
Somelasta fewweeksormonths
annually.Theseseasonalbansare
designedtoprotectfishduring
theirbreedingseasons,for
example,ortoprotectthesea
bottomfromdamage,aswith
shrimptrawlingbans.Otherslast
mostof theyear,orlonger,asin
thecurrentmoratoriumon
fishingintheArctic,whichcould
last 16 years.A totalglobal
fishingbanwouldincrease
stocks,whilehelpingtorebalance
upsetecosystems.Eatingless
lobsterthermidor,forexample,
wouldhelpkeepseaweedforests
ingoodhealth,asthecrustaceans
preyonseaurchinsthatdestroy
kelp– a typeof seaweed.
However,thereareno
guarantees of a full recovery in
ouroceans.AccordingtoPurcell,
somespeciesarealreadysobadly
affectedbyoverfishingthatthey
mightneverrecover.InPapua
NewGuinea,theediblesea
cucumbersthathestudies–
popularinAsiancookery– have
beensovoraciouslyharvested
thattheirpopulationsaredown
toone-hundredthof theirpre-
fishinglevels.“Oncetheyget
downtolessthanoneanimalper
hectare,it’sveryhardforthe
matestofindeachother,
particularlyforthesespeciesthat
aren’tmovingveryfast,”Purcell
says.“Theyhavetocrawlaround
ontheseafloortofindeach
other.”Meanwhile,northof
Australia,someshellfish
populationsexploitedby
Indonesianfishershavedeclined
tothepointwheresofewarenow
reproducingthatrebuildingtheir
populations looks impossible.Theoceans would
be cleaner
FEATURE WHAT IF...3
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