Production of Abalone in recirculation systems
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Abalone farming is a new and developing industry.
The farming of abalone takes place on land, in different types of tanks.
Either the animals are fed with kelp or an artificial diet. Tank design has been very much
related to the type of feed used. Years ago, the animals did not perform well on artificial diets.
Today, this has been turned upside down, hence the type of tanks is a progress of change as well.
Earlier, deeper tanks of approx 1 meter depth, were widely used where the animals were kept in baskets
with plates for the animals to sit on and kelp to feed. Inside the tanks aeration was used for mixing
the water.
Now the development has shifted toward the shallow tank design, called the slap tanks. These tanks are
up to 25 meter in length and 2,5 meter wide, and with a water depth of only 2-5 cm, which is optimal for
feeding with the artificial diet.
The amount of labour involved in the abalone culture has always been a key problem, both for feeding
and for cleaning. However, with the slap type of tanks, the cleaning is partly automatic, and feeding
can be automatic as well.
The abalones have different requirements than fish regarding the water quality.
For some species the oxygen level has to be between 90 and 120 % saturation as growth rate will
be reduced to potentially 50% at just 85 % saturation level. Furthermore the animals are sensitive
to ammonia (NH3) and organic material in the water, and ammonia should at any time be below
0,02 mg/l.
As abalone culture has to be landbased, and high amounts of water is required due to the
water quaility necessary to maintain optimal growth. Pumping cost beside labour has always been a
major costs.
Another problem with abalone farming is the sensitity to a number of ectoparasites, of which, some in
addition to causing direct problems, have the side effect that they reduce the value of the final product.
For several reasons recirculation technology is the only solution for the future abalone production:
- The energy costs can be reduced massively, as the average pumping head within the recirculation
system is much lower than the typical pumping head from the sea
- The investments per produced ton of animals will be reduced, as the necessary tank area will be
very reduced due to the improved growth rate, in the temperature controlled environment.
The tank investment per biomass produced is anyway very high in abalone farming, compared to the investment
in water treatment facility which is a relative small fraction of the total investment.
And the overall investment is thus reduced
- The closed recirculated system can prevent ectoparasites from entering the system.
Furthermore growth on the shells will be prevented, which can improve the sales price
- As labour cost is very much related to the number of tanks to be maintained, an improved growth rate,
which means less tanks per ton of animals produced, will also reduce labour costs
The problem until recently, was that prior technologies for recirculation were not able to produce the
necessary water quality for optimal growth of Abalone. Abalone requires: constant, and low levels of ammonia
at a high pH; low levels of CO2; constant levels of oxygen around 100% saturation in the tanks; and very low turbidity.
Dr. Bent Urup (UNI-Aqua) has, since 1998, been involved in several development projects with companies in Chile,
Australia and New Zealand to develop a recirculation technology for commercial production of Abalone.
UNI-Aqua can now provide a suitable technology for recirculated production of abalone.
The Uni-Aqua concept for Abalone operates with tanks in 4-5 levels for minimising the building costs.
The levels between the tanks is used for cleaning the water, so that the operation in several layers,
does not involve additional energy costs. The average lift in the system for the water used is only about 3 meter.
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Drawing side view abalone system. Use drawing from New Zealand project.
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Like with other species in aquaculture, a competitive production technology is necessary, but to obtain success a good management support is important too.
UNI-Aqua A/S is working together with international companies with management experience within production of Abalone.
So when required, UNI-Aqua can offer a complete package of technical and management support.
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Abalones.
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