COPPER ALLOY MESH IN MARINE
FINFISH CAGE CULTURE
A scoping study in southern Africa
Tom Hecht
ADVANCE AFRICA Management Services cc
Advantages of copper alloys
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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
AVAILABLE COPPER ALLOYS FOR
MARINE CAGES
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.
Most commonly used alloy
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
Scoping study objectives
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.
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 pa
12 farms
Land based
pump ashore
Seaweed for
abalone feed
Mussels, 600-800 t pa, Spanish
raft, Saldanha Bay, 2 farms
Artificial feeds
Oysters: 450 t pa,
mainly PE, Saldanha,
Knysna. Consumed
locally and some
exported EU.
Kob broodtsock
Pemba (Mozambique)
Richards Bay
Planned farms:
Mosselbay - Yellowtail
Saldanha, - 2 x Salmon
Experimental Algoa Bay (Yellowtail)
Richards Bay (Kob)
Yellowtail cages, Algoa Ba
2009 - 2011
Country overview: Mozambique
Current 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 Kob
Investor: HIK Abalone, Hermanus.
Pre-commercial phase 2009-2011 @ US$3 million
Commercial phase 2012> to 2000 t pa @US$ 7 million
Rating
Site
location
Country
Cage type
A++
A++
Pemba
Nacala
Mozambique
Mozambique
Surface
Surface
A+
A+
Saldanha Bay
Mosselbay
South Africa
South Africa
Surface
Surface
A
Algoa Bay
South Africa
Surface/Subme
rged
B-
Gansbaai
South Africa
Surface/Subme
rged
Additional
information
needed
None
Depth profiles,
Bottom type,
Current speeds
Water quality
None
Water
quality
data
Significant
wave
height
andwater
quality data
Depth profiles,
Bottom type,
Current speeds
Significant
wave height
Plus
Seychelles, Madagascar, Reunion, Mayotte,
Mauritius
Possible cage culture areas in outer bay of Nacala
Northern area
(probably too
exposed)
Southern area
Central area
The problems
Net fouling,
Algoa Bay
Predators (Barracuda)
inside net pen
The potential for cage culture
Term
Short
Medium
Long
Years
5
10
20
RSA
Mozambique
5 000
2 000
15 000
12 000
45 000
35 000
Farm
Location Tonnes pa Number of Cage ø Net depth Area/cage Netting required
cages
(m)
(m)
(m^2)
(m^2)
1 Mosselbay
2000
40
35
8
880
35 200
2 Saldanha
1000
18
40
15
1 886
33 943
3 Saldanha
1500
26
35
15
1 650
42 900
4 Pemba
2000
20
25
10
786
15 714
Total
127 757
10 year horizon
50 000
500
35
12
1 320
660 000
20 year horizon
90 000
900
35
12
1 320
1 188 000
TOTAL
1 975 757
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 countries
Regulatory 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 APPROVAL
Dear 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 the
use of Copper Alloy mesh technology in marine aquaculture.
The Directorate has no objections to the use of copper alloy mesh
technology for use in marine aquaculture systems.
Regards
Michelle Pretorius (Cand. Sci. Nat.)
Department of Agriculture, Forestry & Fisheries
Principal Enviornmental Officer: Marine Aquaculture Environmental
Assessment
Tel: +27 (21) 402 7034
Fax: +27 (21) 434 2144
Cell: 082 647 2263
E-Mail: MichellePR@nda.agric.za <mailto:Phumelele.mhlongo@gpw.gov.za>
Private Bag X2 Roggebaai, 8012, Cape Town
Conclusions and recommendations
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).
THE REST
A. Selection of partners for commercial trials
1. 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 trials
2. Anti-fouling demonstration project
C. Implementation and project management
D. Pro forma Budgets
Comparison of Commercial partners
AquaPemba
Stellenbosch /DST
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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
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.
Anti fouling
demonstration trial
 Basic hypothesis: Because
 Demonstrate economic
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.
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)