COPPER ALLOY MESH IN MARINE FINFISH CAGE CULTURE A scoping study in southern Africa
Tom HechtADVANCE AFRICA Management Services
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Advantages of copper alloys
High resistance to macro-fouling in sea water resulting in Improved water flow through cages, Improved DO levels, reduced parasite load, reduced
infections, lower FCR, Higher production as a consequence of faster growth and
lower mortality (no net changes; no stress from predators) The material is strong and predators cannot cause damage
thereby reducing fish losses due to predation and rate of escape of fish from cages.
Lower maintenance: no net changes; no net cleaning Lower costs: avoid need for predator net; avoid antibiotics Reduced environmental impact: can be made from recycled
materials; can be recycled after use; no nets to dispose of. Potential for consumer market positioning as more
environmentally appropriate fish production
Flattened expanded copper nickel: 90%Cu/10%Ni. Used for square rigid cages >30 yrs. Wide range of mesh size and gauges.
Chain link woven UR30TM brass: 64% Cu, 35% zinc, 0.6% Sn, 0.3 %Ni plus micro-alloying elements. Appropriate for many types of flexible enclosures including circular and square cages. This material has been in use for >10 yrs.
Welded silicon bronze (SeawireTM): Comprising 97% Cu, 3% Si plus manganese and micro-alloying elements. Suitable for attachment to rigid structures and for square cages.
AVAILABLE COPPER ALLOYS FOR MARINE CAGES
UR30TM COPPER ALLOY (64%Cu, 35%Zn,0.6%Sn, 0.3%Ni and other micro-alloying elements Yellowtail in UR30
cage. Note limited bio-fouling.
UR30 net being prepared for square salmon cage at Van Diemen Salmon farm, Tasmanaia
Most commonly used alloy
Provide brief overviews of the current state of marine aquaculture in RSA, Namibia and Mozambique.Outline current government policies and recent actions with respect to marine aquaculture developments.Assess the potential size of the cage culture industry in the region.Inform / sensitize commercial operators and fisheries / aquaculture authorities about the merits of alloy cages and assess the potential interest in alloy cages. Identify possible local barriers to alloy cage deployment through interviews with local “environmental” NGOs Identify any possible institutional barriers and or regulatory barriers to deployment of alloy cages.Identify possible partners and location/s for pilot commercial trials Assess acceptability of investment costs and or lease costs Develop an experimental design in collaboration with farmer/s to test the efficacy of alloy cages cf. to nylon net pens. Develop a basic costing for a commercial pilot project if desirable.Develop the logistics for the implementation of a commercial pilot project if desirable.
Scoping study objectives
Country overviews: Namibia Mariculture sites: Walvis Bay,
Luderitz and Swakopmund
14 producers, mainly oysters, 2 mussel farms an d 1 shore based abalone farm. Oyster production 560 – 900 tonnes pa. Exported to SE Asia, Europe and RSA.
Excellent regulatory framework (Aquaculture Act) and streamlined permitting procedures and strongly supported by Government.
Luderitz at core of central Benguela upwelling cell.
Sulphur eruptions prevalent from 50km N of Luderitz – toxic to marine organisms.
Luderitz prone to low dissolved oxygen levels .
Cage culture opportunity – Low to nil (too risky)
Farm locations: South Africa
Country overviews : South Africa Abalone 980 t
pa12 farms
Land based pump ashore
Seaweed for abalone feed
Artificial feeds
Mussels, 600-800 t pa, Spanish raft, Saldanha Bay, 2 farms Oysters: 450 t pa,
mainly PE, Saldanha, Knysna. Consumed locally and some exported EU. Kob
broodtsock
Pemba (Mozambique) Richards Bay
Yellowtail cages, Algoa Bay 2009 - 2011
Planned farms:
Mosselbay - YellowtailSaldanha, - 2 x SalmonExperimental - Algoa Bay (Yellowtail) Richards Bay (Kob)
Country overview: MozambiqueCurrent activities: Prawns (600 t) and seaweed
(1200 t dry)Excellent regulatory framework, excellent incentives for FDI
Cage culture started at Pemba, Cabo Delgado (AquaPemba) Species: Cobia and Dusky KobInvestor: HIK Abalone, Hermanus.Pre-commercial phase 2009-2011 @ US$3 millionCommercial phase 2012> to 2000 t pa @US$ 7 million
Rating Sitelocation
Country Cage type Additionalinformation needed
A++ Pemba Mozambique Surface None A++ Nacala Mozambique Surface Depth profiles,
Bottom type, Current speedsWater quality
A+ Saldanha Bay South Africa Surface NoneA+ Mosselbay South Africa Surface Water quality
dataA Algoa Bay South Africa Surface/
SubmergedSignificant wave height andwater quality data
B- Gansbaai South Africa Surface/Submerged
Depth profiles,Bottom type, Current speedsSignificant wave height
Plus Seychelles, Madagascar, Reunion, Mayotte, Mauritius
Southern area
Northern area (probably too exposed)
Central area
Possible cage culture areas in outer bay of Nacala
The problemsNet fouling, Algoa Bay
Predators (Barracuda) inside net pen
The potential for cage culture
Farm Location Tonnes pa Number of Cage ø Net depth Area/cage Netting requiredcages (m) (m) (m^2) (m^2)
1 Mosselbay 2000 40 35 8 880 35 2002 Saldanha 1000 18 40 15 1 886 33 9433 Saldanha 1500 26 35 15 1 650 42 9004 Pemba 2000 20 25 10 786 15 714
Total 127 75710 year horizon 50 000 500 35 12 1 320 660 00020 year horizon 90 000 900 35 12 1 320 1 188 000
TOTAL 1 975 757
Term Years RSA MozambiqueShort 5 5 000 2 000Medium 10 15 000 12 000Long 20 45 000 35 000
Note: This excludes the potential of the entire WIO region
DISSEMINATION OF INFORMATION AND FARMER RESPONSE Information pack compiled and sent to all public and private sector stakeholders in three countriesRegulatory authorities -- were enthusiastic as they recognised the application to realize development goals.
Farmer response -- cautious optimism to quiet enthusiasm. Not surprising. (Who jumps in first?)
Farmer opinions and questions•Except for Irvin and Johnson, farmers unaware of copper alloy mesh and cages. •University of Stellenbosch aware of copper alloy cages, previous contact with CDA (Africa). •Once aware of benefits = high degree of interest by farmers with finfish farming interests.•Oyster farmers (as expected) expressed a more cautious approach. •Most frequent questions = product lifespan, cost, env. impact, additional floatation.
Primary motivators: Intense biofouling and predators
REGULATORY APPROVALDear Prof. Hecht,
This e-mail serves to inform you that the Marine Aquaculture Directorate(DAFF) has reviewed the information supplied by you to Mr Semoli, on theuse of Copper Alloy mesh technology in marine aquaculture.
The Directorate has no objections to the use of copper alloy meshtechnology for use in marine aquaculture systems.
Regards
Michelle Pretorius (Cand. Sci. Nat.)Department of Agriculture, Forestry & FisheriesPrincipal Enviornmental Officer: Marine Aquaculture EnvironmentalAssessment
Tel: +27 (21) 402 7034Fax: +27 (21) 434 2144Cell: 082 647 2263E-Mail: [email protected] <mailto:[email protected]> Private Bag X2 Roggebaai, 8012, Cape Town
Cage culture in RSA and Mozambique is nascent but interest is growing.Emerging nature provides opportunity to expose farmers to benefits of copper alloy cages from the start.It makes logical sense for the CDA (Africa) to undertake joint commercial trials with industry to prove the local business case. Deployment of copper alloy panels and monitoring at selected sites would be valuable marketing tool.Given feedback, pivotal for CDA (Africa) to develop a marketing brochure that provides indicative costs, a cost / benefit analysis, information on buyback for recycling inclusive of prices relative to new costs, possibility of leasing and costs involved, available mesh size, weight, additional floatation required, assembly modes, etc. FishAfrica - Tradeshow CT, CDA (Africa) should further explore opportunities in the Western Indian Ocean region and in particular by Reunion (which is the most advanced country with respect to marine fish farming in the region), Seychelles, Madagascar and Mauritius.There may be an opportunity for the CDA (Africa) to develop a new product for the oyster farming industries in Namibia and South Africa (but see below).
Conclusions and recommendations
A. Selection of partners for commercial trials1. The AquaPemba Cobia project in Pemba, Mozambique (HIK Abalone)2. The University of Stellenbosch / Dept. Of Science & Technology Dusky Kob project in Richards Bay OR Yellowtail project in Algoa Bay
B. Experimental systems and design 1. Comparative growth and production trials2. Anti-fouling demonstration project
C. Implementation and project management
D. Pro forma Budgets
THE REST
Comparison of Commercial partnersAquaPemba Commercial project Bioregion = Tropical Cobia and kob Commercial phase =
2000 tonnes pa Findings not widely
disseminated but success will result in further investment in WIO.
Total budget to commercial = US$1o M
Stellenbosch /DST Development project Bioregion = Temp/Trop Kob or Yellowtail No direct commercial
phase Findings widely
disseminated but does not necessarily lead to investment in RSA and or WIO
Total budget to completion = R6 M
Commercial trials
Comparative growth and production trial.
Basic hypothesis: Because there is no biofouling the environmental conditions (through flow rate, O2) within the alloy cages should be better than in nylon cages, which will manifest in higher growth rates, lower FCR, lower stress level and “healthier” fish with lower mortality levels.
Anti fouling demonstration trial
Demonstrate economic benefits of copper alloy meshes in four bioregions (Cold west coast to Tropical)
Implementation and project management – project management company to implement and project manage
Pro Forma Budgets – Being drawn up at present.
IDEA FOR CDA (Africa)
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