South African aquaculture production, though limited i\n its contribution to Africa's and global production, has
shown a significant increase over the past decade.
Since the lifting of political and economi-cal isolation in the early 1990s, South Africa has experienced a rapid increase in the development of commercial aquac-ulture. The industry is expected to make a significant con-tribution towards economic growth, job creation, foreign exchange earnings, whilst also con-tributing towards s o c i o - e c o n o m i c development and food security.
According to a recent benchmark-
ing survey performed by the Aquaculture Institute of South Africa (AISA), total aqua-culture production and value in 2008 was 3650 tonnes and R327 million respectively (Britz et al., 2009), growing at a rate of eight percent in production and 32 percent in value between 2005 and 2008.
Aquaculture development in South Africa was initially aimed at the replacement
of high value imported products by local production as well as further extension of local markets.
Success in this regard, was achieved with commercially relevant freshwater (rainbow trout, aquarium fish, koi carp) and marine species (mussels, oysters and abalone).
Mariculture is becoming increasingly important as consumer demand for marine
species will not be replaced by demand for freshwater fish as marine catches decrease.
In South Africa the development of the mariculture industry has being spurred on by some successful aba-lone (Haliotis midae) farms interested in diversifying their activities into finfish mariculture. The indigenous species leaving its explora-
Abalone feed development in South Africaby Lourens de Wet1 & Krishen Rana2
1Feed Technology Group, Stellenbosch University, South Africa, [email protected] of Stirling, Institute of Aquaculture, United Kingdom
Figures 1a&b. Aquafeed sales per province (left) and as portion of total animal feed sales in South Africa during 2008/2009 (AFMA MEMBERS ONLY) (TONNES) (adapted from Chairmans reports, 2008/2009 www.afma.co.za)
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tory phase for commercialisation include Silver and Dusky Kob (Argirosomus sp.) and Yellowtail (Seriola lalandi).
Dynamic growthThe Western Cape Province
show at the most dynamic growth in aquaculture production and development and is promoted by the well-developed agriculture- and fisheries-infrastructure by means of diversification, savings on capital costs and available knowledge.
In terms of value, South African aquaculture was dominated by abalone production, which was R268 million in 2008, representing 81percent of the total rand value of the aquaculture sector.
In addition, exports of South African aquaculture production were made up almost entirely of abalone in 2008, representing 24 percent of total tonnage and 82 percent of the total value of South African aquaculture. Supporting this sec-tor, two Western Cape based aquafeed manufacturers - NutroScience and Marifeed - dominate supply with 77 percent of total aquafeed production (see Figure 1a). Both manufacturers also contribute to aquafeed exports.
Total aquafeed sales represent 0.03 per-cent of total animal feed sales (see Figure 1b), and utilises similar major ingredients (with the exception of fish oil and fish meal) than the monogastric animal feed industry.
South Africa has a well-established feed industry and related production sector, which provides a wide range of raw materi-als and fine chemicals that can also be used in the formulation of relevant aquafeeds.
However, information on the nutritional value and application of some of these ingredients are often limited with regard to specific application to indigenous species.
Utilising both hot and cold extrusion in production of aquafeeds, the sec-tor is supported by a well-developed companion animal food and human pasta production industries in terms of techni-cal know-how.
However, hot extrusion predominantly utilises conditioner-assisted single screw extruders affecting the physical appearance of fish feed in high-protein starter and high-energy grower diets formulated with limited carbohydrate content. Irrespective of appearance, a feed conversion ratio of below 1:1 is achieved on commercial farms.
University supportThe Western Cape aquafeed industry is
technically supported by the Universities of Stellenbosch and Rhodes (Grahamstown) which have good facilities for prototype product development and evaluation. These i n s t i t u t i o n s also provide research and training oppor-tunities for resident and distance educa-tion students. The Feed Te c h n o l o g y Group of the University of S te l l enbosch focus on:
R e d u c i n g the environ-mental impact of aquaculture through develop-ing low pollution aquafeeds and environmentally sustainable feeding practices
Utilization of food processing and industrial by-product streams as alternative feed ingredients for fishmeal and fish oil in marine finfish feeds
Functionally enriching of aquafeeds towards sustaining feed shelf life, production performance and end-product health benefits
Abalone productionIn terms of South African abalone produc-
without cost as it is estimated that more than R7 million is spent annually on binding costs for abalone feed in South Africa contributing to 25-45 percent of the cost of various feeds. In addition direct feed loss represents an unrealized production of abalone worth more than R23 million. Efforts to either reducing binding cost or further improve water stability will have a direct impact on the cost-effectiveness of abalone production.
• The successful implementation this strategy has resulted in a reduction in abalone feed price by more than 20 percent to below R14 per kg in the past three years without compromis-ing production performance.
However, further optimisation of the functional and nutritional value of abalone feed and improving feeding strategies is critical to ensure competitiveness of the abalone industry.
ing on sexual maturity, animal size and season. Preliminary research at Stellenbosch University has shown that a reducing of moisture loss to levels below five percent can be achieved through diet intervention.
• Improving gut condition and supporting digestive function. As no prophylactic antibiotics AGPs are currently registered for use in South Africa for use in aqua-feeds, novel alternatives such as prebiot-ics, organic acid and phytogenics are trialled and implemented into abalone feeds with good success. Utilising cold extrusion, enzymes specifically hold great promise to improve nutritional value of plant proteins often considered to play a role in temperature-induced bloating.
• Improving feeding behaviour by utilising chemo-attractants to help stimulate and support olfactory and gusta-tory response. Abalone are known slow feeders that requires feed to be water stable for up to 24 hours - even 48 hours on some farms - to allow good feeding response by all animals in a system.
• Reducing costs related to abalone feed stability. Abalone feed has proven to be up to 92 percent stable in terms of nutrient leaching and disintegration after 48 hours of water exposure in commercial production systems. Such stability however does not come
tion, the current feeding practice is feeding 50 percent of produced abalone on wild collected and harvested macro algae fed every 48 hours while the other 50 percent is grown with artificial dry feed fed every 24 to 48 hours.
Regulations on wild macro algae harvests are reaching an approaching limit on the availability thereof and there is a growing trend to produce more abalone using artificial dry feed. A feed development strategy was hence formulated by Stellenbosch University to opti-mise feed-related production performance and efficiency for abalone production (see Figure 3),
focussing on four key aspects: • Increasing muscle yield: by means of
reducing handling- and processing-related moisture loss. The costly loss of moisture from the muscle of abalone during live exports may be in the region of 18 percent, depend-
More inforMation:Lourens de Wet,Feed Technology Group,Division of Aquaculture,University of Stellenbosch, Private bag X1,Matieland 7602, South AfricaTel +27 21 8082545,Email: [email protected]
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tonnes and of a value of Euros16,540 million was imported. In the same year EU exported 1,774,000 tonnes of a value of Euros2934 million.
LegislationFor the past 30 years an important
number of legislation concerning aqua-culture was prepared by the European Institutions, covering subjects such as economic, social, safety, hygiene and envi-ronmental matters.
Nevertheless, a general framework containing the guidelines of its develop-ment was missing. This is why, in 2002, the European Commission has prepared a Strategy for the sustainable develop-ment of the European Aquaculture, which was adopted by the competent European Institutions the same year.
The main objectives of this strategy were to create a long term and secure employment, in particular in fisheries dependent areas, to assure the availability to consumers of products that are healthy, safe and of good quality, to promote high animal health and welfare standards and to ensure
an environmentally sound industry. At the same time, the fundamental aim of the strategy was the maintenance of the competitiveness, the productivity and the durability of the aquaculture sector.
A prerequisite for the realisation of these objectives were:
To increase the production volume by an average four percent per year. This should focus mainly the molluscs’ production, the development of know-how for new species and strains from selective breeding and the promotion of the ‘organic’ production
To enlarge the market outlets by con-tributing to the ability of the aquaculture business to cope with market demands, by opening new markets, by improving the integration between production and sales, by developing new tools to gather statistical information on production and markets and
by stimulating demand through a convincing quality policy
To undertake social actions in order to adopt training programmes to aquaculture needs, to recognize the role of women in the production and the administration of the aquaculture firms and to challenge the role of aquaculture in rural development and reversing the decline in coastal communities;
To improve governance in the design and implementation of policies and measures that influence the development of aquac-ulture, notably with the view to ensuring proper stakeholder participation
"The total estimated turnover of the aquaculture sector in EU is
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F: EU Aquaculture
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removed some mono-ortho PCBs and little of the non-ortho PCBs and PBDEs.
However, the recent development of a two-step process of activated carbon plus thin-film deodourisation can remove most DL-PCBs and PBDEs to provide a FO with very low pollutant TEQ levels.
The present study investigated the effects on diet and flesh pollutant concentrations when replacing a northern FO, containing high levels of pollutants (cNFO control diet), with either the same oil which had been cleaned using the two step protocol above (deNFO decontaminated diet), or with a blend of southern FO, soya oil and rapeseed oil (4/3/3 by volume; FO/VO diet).
These three diets were fed to triplicate groups of salmon in 125m3 cages for 11 weeks. The effects of these dietary treatments on dioxin, DL-PCB and PBDE, as well as n-3 LC-PUFA concentrations in feed and flesh are reported.
From Norway to ScotlandThree 9mm diets were prepared at the
BioMar Tech Centre, Denmark and contained 33% protein and 34% lipid.
Atlantic salmon of initial weight 0.78kg were cultured using one of the three diets above between July and October 2006 under ambient photoperiod and average temperature of 11.5 ± 2.7oC at the Fjord Research Station, Dønna, Norway.
Samples of fish flesh were col-lected at the start and end of the trial. Nine fish per dietary treatment were sampled and the Norwegian Quality Cut (NQC) wrapped in foil and frozen at -20oC and transported to Stirling where they were stored at -70oC until analysed. The three NQCs/pen were pooled to provide three samples/dietary treatment. Samples of feed were collected at the start of the trial and wrapped in foil and frozen as for flesh.
After the 11-week feeding period the fish had an average weight of 2.19kg and there were no differences between diets.
SGRs were in the range 1.34-1.35, TGC
between 3.86 and 3.92 and FCRs in the range 0.96-0.98. The cNFO diet contained 17.4 ng TEQ/kg, for the 29 WHO dioxin + DL-PCBs assigned WHO TEF values and this value is significantly above the EU limit value of 7ng TEQ/kg.
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