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The effect of triploidy on the growth and survival of the indigenous abalone, Haliotis midae, over a 24 month period under commercial rearing conditionsSchoonbee, Lize 03 1900 (has links)
Thesis (MScAgric)--Stellenbosch University / ENGLISH ABSTRACT: Triploidy is the genetic state of containing three sets of chromosomes per cell in stead of two
as in diploid organisms. The South African abalone (Haliotis midae) is naturally a diploid
organism that sexually matures between four to eight years of age. Early sexual maturity is a
disadvantage in cultured abalone stock, as the process of gonad development and spawning is
energy demanding, causing energy to be diverted away from somatic growth. This same
problem has been extensively experienced in diploid bivalve molluscs, where triploidy has
since been applied as a means to prevent sexual maturation from occurring, thereby speeding
up the growth process and shortening the time to marketing.
Because triploidy was effective in bivalves, it was thought that it could contribute to
faster growth in abalone as well. A procedure for the induction of triploidy in the abalone,
Haliotis midae, was developed by De Beer (2004) and yielded up to 100 percent triploidy in
treated abalone larvae. The next step was to compare the growth of the diploids and triploids
to establish whether there was indeed a growth advantage on the part of the triploids, in view
of commercial application.
By using the same techniques as described by De Beer (2004), three groups consisting of
triploid and diploid siblings were produced and subscribed to a comparative growth trial. The
groups were spawned in three different seasons. The main objective was to establish whether
there was in fact a difference in growth between diploid and triploid siblings, and whether
seasonal effects were associated with growth advantages for either triploids or diploids.
The two growth parameters measured were shell length and body weight. Measurements
commenced at eight months of age, when the abalone could be individually tagged and
continued up to the age of 24 months.
The over-all results provided no convincing evidence of statistically significant faster
growth of triploid juveniles compared to that of diploids up to two years of age. Growth
differences were detected between seasons, but could not confidently be ascribed to seasonal
environmental effects. The regression of shell length to body weight was similar for diploids
and triploids. / AFRIKAANSE OPSOMMING: Triploiede organismes bevat drie stelle chromosome per sel in plaas van twee soos dit
normaalweg in diploiede diere voorkom. Die Suid Afrikaanse perlemoen (Haliotis midae) is
van nature ‘n diploiede organisme wat tussen die ouderdom van vier tot agt jaar seksueel
aktief word. Vroeë seksuele aktiwiteit is ongewens in kommersiële akwakultuur aangesien
energie spandeer word aan gonade ontwikkeling in plaas van somatiese groei. Dieselfde
probleem is vroeër in die oester bedryf ondervind waar dit deur middel van triploiede
induksie aangespreek is. Triploiedie veroorsaak steriliteit en kan gebruik word as ’n metode
om steriliteit op groot skaal te induseer. Steriliteit sou dan meebring dat meer energie
beskikbaar is vir somatiese ontwikkeling, wat verhoogde groeitempo en n verkorte tyd tot
bemarking beteken.
Op soortgelyke wyse is dus gepostuleer dat triploiedie in perlemoen ook tot steriliteit kon
lei. ‘n Triploiede induksie metode was ontwikkel deur Mathilde de Beer (2004) wat ‘n hoë
persentasie triploidie in geinduseerde perlemoen opgelewer het. Die volgende logiese stap
was om die groei van diploiede diere met die van triploiede diere te vergelyk om te bepaal of
triploiedie wel ’n groei voordeel tot gevolg het met die oog op kommersiële toepassing.
Deur van dieselfde tegnieke as De Beer (2004) gebruik te maak, is drie groepe, elk
bestaande uit verwante diploiede en triploiede diere, geproduseer en ingeskryf aan n
vergelykende groei proef. Die groepe was in drie verskillende seisoene geproduseer. Die
hoof doelstelling van die proef was om groeitempo van diploiede en triploiede diere te
vergelyk, asook om die invloed van seisoen op groei van diploide en triploide te bepaal.
Twee groei eienskappe naamlik skulp lengte en liggaamsmassa is gemeet vanaf ‘n
ouderdom van agt maande (wanneer die diere individueel gemerk kon word) tot ‘n ouderdom
van 24 maande.
Die algehele resultate het gedui op geen betekenisvolle verskil tussen die groei van
triploiede en diploiede perlemoen tot op die ouderdom van twee jaar. Verskille het
voorgekom in die groei tussen seisoene, maar daar kon nie bewys word dat die verskille die
gevolg van seisoenale omgewingseffekte was nie. Diploiede en triploiede het dieselfde skulp
lengte tot liggaamsmassa verhouding getoon tot op twee jaar ouderdom.
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Establishing an abalone venture in South Africa : a critical review of AquamartNorval, Alex 12 1900 (has links)
Thesis (MBA (Business Management))--Stellenbosch University, 2008. / ENGLISH ABSTRACT: This report begins with a look at the ever increasing world population and the effect
this is having on the world's food production. While the demand is increasing with
the rise in population, the supply side is finding it difficult to produce enough food due
to a number of pressures. The report then goes further by suggesting a source of
food that holds great potential for the future which, if it reaches its full potential, could
go a long way in providing a sustainable source of food for the next generation. This
source is Aquaculture, which is discussed through a look at both the advantages it
provides and the challenges involved within this industry.
Furthermore, the report takes an in depth look at a sub-section of the aquaculture
industry, namely the farming of abalone, firstly in general, but then also more
specifically the farming of abalone in South Africa. Abalone are mostly sold in Asia
as a high priced delicacy and occurs naturally off the coast of South Africa, however,
due to over fishing and poaching over the past three decades, the South African
government has now introduced a total ban on the diving and selling of wild abalone,
or as it is commonly known in South Africa, Perlemoen. It is therefore now up to the
small number of abalone farms on South Africa's coast to fill the void left in the
international abalone market for Haliotis midae.
The second half of this report looks at one company in particular, Aquamart, which
was a company established in 2003 by 5 MBA students with an ambitious plan of
setting up an abalone farming facility. All of Aquamart's aspects are discussed,
including its business plan, financials, senior management and its strategy. These
areas are then critically reviewed in order to try and establish what Aquamart
succeeded in, but also what went wrong, and why the company ultimately had to be
closed down in 2005. This report aims to identify some of the barriers within this
industry and also for Small and Medium Enterprises (SMEs) in general, which can
hopefully be used by future entrepreneurs in order not to repeat the mistakes made
by Aquamart. / AFRIKAANSE OPSOMMING: Die verslag begin deur te kyk na die al groeiende wereldbevolking en die druk wat dit
plaas op die wereld se voedselvervaardiging. Saam met die druk van die groeiende
vraag, is daar ook verskeie eksterne vorme van druk op die aanbod van voedsel. Die
verslag gaan verder deur een moontlike bron van voedsel voor te stel wat sal kan
help om aan die vraag te voldoen, maar slegs indien dit korrek aangewend word.
Die bron is akwakultuur, en die verslag kyk na die industrie se voordele asook na van
die uitdagings wat die sukses van die industrie kan beinvloed.
Verder ondersoek die verslag oak een van akwakultuur se sub-industriee, naamlik
die boer met perlemoen, eers op 'n globale skaal, en dan spesifiek in Suid-Afrika.
Die perlemoen wat grotendeels as 'n luukse voedsel op die Asiatiese mark verkoop
word kom natuurlik op die kus van Suid-Afrika voor, maar as gevolg van die swak
bestuur van die natuurlike hulpbron, gepaard met die onwettige smokkeling van
perlemoen, is die natuurlike perlemoen nou 'n bedreigde spesie in Suid-Afrika, en het
die land se regering 'n verbod geplaas op die uithaal en verkoop van wilde
perlemoen. Dit is dus in die hande van die Suid Afrikaanse perlemoenplase om in
die wereld se vraag na H. midae te voorsien.
Die tweede helfte van die verslag doen 'n gedetailleerde ondersoek op die
maatskappy Aquamart, wat in 2003 gestig was deur 5 MBA studente met die oog om
'n perlemoenplaas in Suid-Afrika op te rig. Die vernaamste aktiwiteite van Aquamart
word in die gedeelte bespreek, insluitende, onder andere, die besigheidsplan,
finansies, algemene bestuur en Aquamart se besigheidstrategie. Die verslag doen
dan 'n kritiese ondersoek op Aquamart om te probeer vasstel hoekom die bestuur in
2005 geforseer was om Aquamart se deure te sluit. Die hoop is om lesse te leer uit
Aquamart se mislukking wat kan dien as 'n riglyn vir toekomstige perlemoenboere,
asook klein en medium-besighede in die algemeen.
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