Farmer’s Weekly – 09 August 2019

PERSPECTIVES IN AQUACULTURE

During the run of this

column over seven

years, approximately

1 800 enquiries and

replies were received

and sent out.

My final article, and a

review of seven years

T

he first Farmer’s Weekly aquaculture

article in the current series was

published on 14 September 2012.

Like several subsequent articles, it

covered the use of tilapia in warm

water aquaculture in South Africa, and

discussions around species. Today,

169 articles and nearly seven years later, a

lot of water has flowed under the bridge.

The first articles were written at a time

when Nile tilapia (Oreochromis niloticus)

were bursting onto the international

aquaculture scene, with fast-growing,

disease-resistant and deep-bodied forms

being widely bred and improved in East

Asia. At this time, the species was still

largely absent from South African farms.

Efforts had been made to ‘improve’ our

local Mozambique tilapia (O. mossambicus)

in terms of growth rate, colour forms, age at

maturity, and general suitability for farming.

However, the phenotypic plasticity of the

species and the ability to change its lifestyle

radically under different environmental

conditions worked against selective

breeders. Fish that appeared suitable in

wild populations, with deep bodies and late

onset of maturity, reverted almost instantly

to early-maturing, slow-growing fish in

the aquaculture environment. This led to

pressure by farmers for the use of Nile tilapia.

History has taught us the cruel lesson

that whatever legislation may be enacted,

fish will still swim up rivers and invade

catchments where environmental conditions

are suitable. As neighbouring countries

adopted almost exclusive use of Nile

tilapia in aquaculture, our shared rivers

were soon invaded by the species, which

then hybridised with Mozambique tilapia.

How far this invasion has progressed is

now the focus of scientific investigation

and surveys commencing this summer.

Other forms of warm water aquaculture,

identification of freshwater fish species,

conservation, and the design of culture

systems formed the bulk of the topics

covered in the seven years of publication.

Surprisingly, two articles on the potential

farming of bass prompted the most

interest from the public, closely followed

by requests from people wanting to

know how to start off in aquaculture.

QUERIES FROM READERS

A very wide spectrum of people asked me

for information. Most common were folk

from the rural areas who had heard about

fish farming, yet could find no further

information on how they could get involved.

It was always difficult to reply satisfactorily

to these people as the impression that many

held was that aquaculture was like chicken

farming: a cut-and-dried formula for success

that could be learnt from a manual.

I also received several enquiries from

investors who wanted to copy the farms that

have sprung up in tropical Africa and to

the north, and who wondered why similar

enterprises were lacking in South Africa.

Other discussions revolved around the

use of existing infrastructure and system

designs. Aquacultural enquiries were

received from Jordan, the US and South

Korea, as well as many African countries.

Over the seven years, I thoroughly

enjoyed writing the series and replying

to the often enthusiastic enquiries.

Wishing you all well in the future. ▪FW

BY NICHOLAS JAMES

Nicholas James is an ichthyologist and
hatchery owner. Email him at
[email protected]. Subject
line:Aquaculture.

RIGHT:
Nicholas James’s first
aquaculture article
in Farmer’s Weekly. It
appeared in the issue of
14 September 2012.

28 farmer’sweekly 9 AUGUST 2019

W

arm-waterfarming,orfish

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AQUACULTURE
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Tilapia:why quality
seed counts
ADVENTURES
AQUACULTUR
BYNICHOLASJAMES
establishedinmanycountries,infishfarms
especiallyInassociationinthewithFarEast.UK
universitiesandSwansea,suchmeanwhile,asStirling
Thaialsorecentlyaquaculturalistsdevelopedhave
highlyformsofproductiveNiletilapia.
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heatedUK,meaningfacilitiesfreshinthe
tilapiamanysupermarketsis availablein
aroundIf thetheBritishcountry.can
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andWestotherAfrica,countrieswhereinthe
Nileareusingtilapiathisis indigenous,species
successfully.Africa,thespeciesInSouthernhas
beencontroversy,introducedandamidis
beingandZimbabwe.farmedinZambia
numbersEscapesintobylimitedriverssuchas
thehaveZambeziseentheandspeciesLimpopocome
toMozambiquedominatethetilapiaindigenous(called
bluekurperinSA).
Ashybridiseda result,populationswehave
ofcatchmenttilapiainintheSouthLimpopoAfrica.
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noofthosewaythebeingequivalentfarmed
soFarsuccessfullyEast– farfromintheit!
IDEALBluekurperFORareFARMINGindigenous
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eastIncoastalsomepopulations,lowlands.
overbluekurper3kg– ascanlargegrowasNileto
tilapia.extremityIntheoftheirsouthernrange
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9,5°CtoNile– whichtilapiaareorthelethal
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below11°Cto13°C.
Evennaturalatthisrange,limitwhereoftheir
you’dtobeenvironmentally-expectthefish
stresseddistinctpopulationsorstunted,are
fast-growing,latematuringdeep-bodied,andlarge-
sized,aquaculturewithsignificantpotential.
fastTheseastheirstrainsmoregrownortherlyas
cousins,temperaturesbutat(18°Clowerto
26°C),forfishmakingfarmerstheminSouthernideal
Africa’s•NicholastemperateJamesis anzones.
ichthyologistRivendellHatcheryandownernearof
Grahamstown,fishforaquariums,whichfish-raises
farming•ContactandNicholasstocking.at
[email protected]‘Aquaculture’in the
subjectlineof youremail.▪FW
‘TILAPIAINSAHASFARMINGFAILED
DUEUSEOFTOPOORTHE
QUALITYSEED.’
36 |farmer’sweekly| 14SEPTEMBER 2012
BELOW:NileX
tilapiaMozambiquehybrids
sourcedLimpopofromRiverthe
andusein smallcurrentlyfishin
farmsin Venda.
FARWildBELOW:pure-
strainOreochromisfemale
mossambicusfromthe
EasternPHOTOS:Cape.
NICHOLASJAMES