HIGH VALUE AQUACULTURE PRODUCTION

Mr. J. A. YOUNG

INTRODUCTION

Though the world, farmers, traders, planners and investors are watching the progress of modern aquaculture, the dynamic markets to be secured, the use of sophisticated technology, and the dramatic increases in production. It is clear that there is a successful industry, the ‘star’ sectors, such as shrimp and salmon, have shown strong, expanding markets,good profitability, and growth in production often more than 30% annually, which has been the envy of many other industries. This success has been associated with increasingly sophisticated technology, and in the case of salmon, perhaps the most dramatic case, increasing mechanisation, and the emergence of ‘industrial’ approach to production. It has also been very closely dependant on effective market development.

High value methods of aquaculture are quite clearly defined in a range of cases, and details can be found in many of the standard texts.

SPECIES CHOICE AND PRODUCTION CHARACTERISTICS

There are many forms of aquaculture, involving a range of species, habitats, production methods and resource requirements. To assess the nature of aquaculture and its relationships with the aquatic environment, and before considering projects in detail, it is useful to consider adopting a ‘systems’ approach. A wide range of species is involved, though an even range is potentially cultivable. Continuing research brings increasing numbers of species within these bounds, but only certain species are likely to be commercially viable for use. Although species may differ widely in habitat, behaviour and physiological response, there are in fact many common elements in the relationships between species, system and environment. Thus we will see that common links occur in areas such as stocking density, feeding quality, density and opportunity, water requirements, and waste production. The implication of this is that we can find many similarities across species when used in aquaculture production. In most geographical or market areas, there are usually certain clearly defined species of interest for aquaculture. The main factors to consider are usually:

Market value; high market value makes possible relatively sophisticated aquaculture techniques, and may support some research and development in early production stages. Low market value makes it difficult to consider any but the most basic methods of aquaculture.

Overall ease of culture; tolerance of crowding, hence lower capital costs per unit of capacity, and ease of feed distribution, management methods, etc. Low disease risk improves overall project risk. Good growth rate increases stock turnover, hence lowers capital cost per annual production. Good environmental tolerance reduces water requirements, and/or need for close environmental monitoring or control.

Simple feeding requirements reduces need for sophisticated, expensive feeds and feeding systems, simplifies overall management. Permits routine and large-scale production. In many cases, feeds determined system employed-eg natural feeding or artificial feeds.

Simple hatchery techniques with full life-cycle control; routine supply of fry, with reliable production planning hence lower operational costs, less risk. Year-round larval supply improves utilisation of holding facilities, particularly of hatchery. Difficult hatchery techniques require sophisticated and expensive systems.

Simple handling/harvesting requirements: permits ready examination, grading treatment, regular and reliable harvesting, development of larger-scale production systems.

To illustrate the use of these criteria, Table 1 summarises the use of the most important preliminary screening criteria associated with typical higher-value freshwater aquaculture species. Certain of these, such as rainbow trout, salmon and eels relatively well-established in aquaculture, and can be adapted readily to local conditions. Others may not be fully known led at a commercial scale in the region concerned, and remain to be evaluated.

Table 1: Screening criteria for candidate species

PRODUCTION SYSTEMS

Trout, eel,carp, catfish and tilapia are all being grown in various parts of the world in hyper-intensive systems, sometimes, incorporating complete environmental control, and water recycling to conserve water and allow units to be set up almost anywhere. Such systems, and other such as fish/hydroponic units, are increasingly being proposed or marketed as complete turnkey ‘food production package’. The most common units for higher value fresh water species are intensive tanks, raceways or cages.

Tanks and raceways

Various designs are used. Because of associated high capital operational costs, they are principally used in intensive, commercial-scale operations where high market prices can be realised, and in hatcheries, with high value/biomass and greater need for high-quality controllable husbandry conditions.

Tanks can be virtually any shape. Although round may be more expensive, they are superior in terms of flow characteristics and thus waste removal and water quality. Tank size is determined by economic and management considerations. Generally, larger tank is are less expensive on a per unit volume basis. Tanks much greater than 10m in diameter are difficult to design, install and manage. As a general rules, a diameter depth ratio of 5–10: 1 is desirable to ensure good cleaning.

Raceways are large, elongated tanks. Because of their shape, water flow characteristics are more even and predictable, though as water quality changes down their lengh, husbandry characteristics may be inferior. Length: width: depth ratio should be around 30:3:1. An advantage of raceways is that they can be terraced, eg down a slightly sloping site, with intermediate cascade aeration between each stage.

Water supply should be around 0.5–11 kg fish-1 min-1. Current velocities would normally be between 10 and 25 cm s-1, though this depends on species requirements, stock size, etc. Tanks normally have a peripheral, tangential inflow and a central drain, with a circular vortex water movement. This allows velocities within the tank to be controlled independently of water flow.

Raceways normally have an inflow at one end and an outflow at the opposite end. Design is critical ideally, water should have a laminar flow and approach “plug” flow conditions in which the entire water column moves at the same velocity, thus eliminating dead spots and short-circuiting and maintaining a high cleaning efficiency. The inlet should be full width and baffles may be necessary to reduce turbulence. Unlike tanks, water velocities are entirely dependent on flowrate.

Tanks and raceways can be fabricated from a variety of materials. Costs, durability and a smouth interior surface to reduce risks of abrasion damage are important. Simple, inexpensive tanks can be fabricated from sections of large dia meter concrete pipe embedded in concrete and finished inside with a skim of fibreglass or plaster. France and liner tanks and raceways are also very cheap. Otherwise GRP (fibreglass) - expensive, but light and very smooth, and brick, concrete block or reinforced concrete - cheap, but much rougher - need good plaster finishing - are commonly used. Foundations often need care, particularly for heavier units, soils need to be checked for strength, etc, and some bedding may be needed.

Water supply demands are usually greater than for pond systems, either:

-  higher quality, eg for hatchery supplies:

-  larger quantities, continuous supply, for intensive ongrowing.

For hatchery water supplies, it is common to use a sand filter, often eg a sub-sand beach filter, a settling/reservoir tank and a series of mechanical filters, such as swimming-pool filters and cartridge filters, to remove pathogens and finer solids. This is particularly important for live feeds and early lifecycle stages. Ongrowing systems typically have a large pumping station, a distribution chamber, and pipe or channel supplies to the tank or raceway units. Pumps usually run continuously and have to be carefully designed to minimise operational costs. Distribution systems have to be eleanable, particularly wastes. Double supply lines are something used, to allow one to be cleaned white the other is operational.

Cage systems

Cages are perhaps the most versatile and cost-effective units used for aquaculture production in estuaries, coastal regions and the open sea, they provide easily manageable holding volume at relatively low cost. The variety of cage designs has arisen out of attempts to deal with a number of (at times conflicting) design objectives.

-  providing a reasonably stable shape, to avoid stressing the stock, and to provide a stable working environment:

-  providing adequate water exchange to satisfy metabolic requirements of stock and remove wastes from the cage area:

-  absorbing or deflecting environmental forces, to maintain the structural soundness of the system;

-  providing an efficient working environment, for routine husbandry, and where equipment and materials (harvested fish, feed, tanks, and bins, etc) can be handled.

maintaining position, to provide a secure location, free from navigation hazards, etc.

As Table 2 indicates, they may have specific advantages. However they cannot be developed in every location.

Table 2 Comparative advantages of cage systems

A cage system behaves 'dynamically' - forces affecting the cage frame are transferred to the net, to other cage frames and to the mooring system, and the corresponding motion is also transferred. This will affect both the durability of the system, and the acceptability to the stock. Cage elements tend to be designed either as flexible or as rigid stuctures; cage systems are usually a combination of these. Some basic concepts environment and stock holding are:

-  theoretical carrying capacity of a cage depends, on the open net area across the current flow (where present);

-  carrying capacity depends on mesh area, degree of fouling, transmission factor of netting;

-  in cage groups, cages downstream of currents have poorer water flow and hence carrying capacity;

-  if tidal flow is zero (eg at top or bottom of the tidal cycle), there is to water ex change;

While these are useful in estimating water exchange, there are several other factors:

-  the stock itself creates water flow, usually in a vortex pattern, with new water entering the base of the cage.

-  there may be convection and density currents, also local currents moving water through the cage base.

-  there is some movement of water due to wave and wind action, particularly n the top 1–2m of the cage.

A further environmental factor in cage systems is the removal of wastes. Generally, ammonia and carbon dioxide can be dispersed in normal water flows. However, solid wastes (food and faeces) tend to deposit below or around the cages themselves. Their dispersion, and their probable effect on the cages will be determined by :

-  their sedimentation rate;

-  currents in the water column;

-  local bed profile and localised currents;

-  the leaching rate from the sediment;

Cage frames : are positioned on or near the surface, normally support the net, hold the flotation elements, connect to the mooring system or other cages, and may carry decking on which various loads can be carried. Some designs also incorporate a handrail. The main types are as follows:

Wool/bamboo : this is probably the simplest, cheapest and most widely used frame type in tropical areas where sites are relatively sheltered. Frames are nailed, pinned or tied together, and are usually slightly flexible. As the frames are usually quite light, they do not always incorporate a working deck.

Wood and steel : these are perhaps the most widely used types, and if properly designed, can cope with moderately severe exposure. Frames are usually square, of 7 to 15m side, and normally incorporate decking and handrail.

Steel/aluminium frames are considerably more expensive than the previous types, and are commonly used for larger cages, typically 10 to 20m. square. For exposed conditions, these systems require careful design and high-quality fabrication.

Flexible tube, usually butyl rubber, is commonly used for moderate to high exposure designs, typically in 15–20m diameter near-circular structures of 6 to 12 sides, or smaller 5–12m square frames. This method is similar in cost to steel/aluminium. They system lies in the wave zone but is so flexible that absorbed stress is minimised. The whole system is held open in shape by its mooring connections.

Plastic pipe - normally PVC or ABS is used in a similar way to flexible tube, though for smaller cages - 2–5m square of 5–15m diameter, which are more rigid design. These designs are approximately similar in cost with wood/steel systems. The cage system rides in the wave zone but is reasonably flexible, and allows larger waves to wash over through. Fatigue cracking and brittleness from UV exposure are among the main problems.

Where flotation is not already incorporated in the frame structure (eg plastic or flexible tube systems), it must be provided and attached to the frame.

Plastic flouts - buoys, etc can be quite useful for smaller flotation requirements; these can be lashed inside a support framework, or tied together through handles, eyes, etc for heavier loads.

Drums - these are typically plastic chemical drums or steel oil drums. These are widely laid horizontal, tied between or below cage framework, as main flotation units. Depending on the amount of protection against UV or corrosion, these can be reasonably durable, though sometimes relatively expensive.

Polystyrene block - perhaps the most common flotation material, used either uncovered; or inside GRP or plastic casings, block can be sized for specific designs, and can be easily positioned in cage framework.

The main stock nets are normally suspended from within the cage frame. Typical dimensions range from 3 to 20m across, 3 to 10m deep. Most commercial operation use nets of 250 to 100m3 in volume, corresponding to about 200 to 500m2 of netting. This is usually assembled in several panels, with suitable mounting rope, loops, and other fixings or attachments. At least 50cm of netting, sometimes of lighter grade, is extended above sea level, usually fixed to the handrail or a similar support, as a 'jumper' to prevent the escape of fish. Additional, lighter nets are commonly placed above and around the cage to deter predators.

As the nets must be handled regularly, and in most cases frequently changed, they should be relatively light and manageable, yet durable. They should not cause damage tot he stock, whether through trapping or abrasion.

Mooring systems typically comprises :

-  fixing devices; typically anchors, blocks or holdfasts such as shore fixing pins.

-  connecting lines; usually a combination of chain, cable and rope, sometimes with additional

-  components buoys, weights, etc to modifiy the elasticity of the line.

-  surface gera; lines, platforms and/or buoys to which individual cages or groups of cages can be attached, and which can be used as part of the operating system for the cages.

-  connecting gear; chains, shackles, pins, hinges and links, together with 'shock absorbers' such as rubber tires, buoys, etc to limit wear between specific components.

WATER DEMAND IN INTENSIVE AQUACULTURE SYSTEMS

Results from a range of production systems are shown in Table 3. Quantities per tonne of production vary widely, determined primarily through managed water exchange associated with intensity of production (i.e stocking density and use of feeds and fertilisers), but also through physical factors such as seepage and evaporation. It must of course be clarified that these figures do not represent actual consumption, but represent the quantities of water which have to be made available to bring about specified forms of production. The main implications are then the opportunity costs and the quality changes involved.

Table 3 : Water requirements per tonne of aquaculture producion.

Source : Adapted from Philips, Beveridge and Clarke, 1988
Estimates by author from industry standard production rates

TECHNOLOGY OPTIONS FOR INTENSIVE, HIGH-VALUE AQUACULTURE

Yields from high-technology systems can be impressive. Can then the salmon farms of Western Europe, the recycle eel and catfish systems - indeed can be whole high-technology approach be an answer to our needs for aquaculture production? The answer, of course, is maybe, and sometimes but certainly not always'. Wet then are the critical factors-how can we decide whether to use high technology, and if so, how much and what kind to use? How should we choose the technology once we decide to use it? First some general points-maybe self-evident, but often overlooked:

-  Aquaculture still relies fundamentally on principles of sound animal husbandry - good stock, the righ environment, good feeding, and management. Technology can support these but not substitute for them. Can you provide the husbandry?

-  Technology can be expensive; can the market price and the projected revenues support the price of technology?

-  Intensive, high technology systems in particular, require ample resources; good quality feeds, energy, good or controlled quality water, effective disease control, skilled staff and good management. Are these available?

-  Off-the-shelf technology often looks (and sometimes works) better on-the-shelf. Does it really match what you need?

-  Technology does not necessarily transfer well from species to species, or from location to location. Are you venturing into the unknown?

-  Technology can offer better control, but at the expense of greater dependence. What happens if it goes wrong?

It always pays to ask these basic questions first. To consider some of the specific areas where technology can be used:

Systems These are several different types of high technology aquaculture system on the market today, ranging from packaged cage units, cage barges and converted ships, to package recycle systems and modular hatcheries. Generally, there are three approaches in current use.

1. Hardware - this has the advantage of being simple, relatively flexible, and if the firm is reliable, well-proven. However, the onus is usually on the buyer to decide whether the system will work in their own conditions, and whether they have the resources to operate them. Reliable firms will offer advice, and should be able to offer case studies, and ideally contacts concerning similar projects. Reputable suppliers will also advice the client if their own systems are unsuitable, or whether the client needs to change projects ideas. In some cases, the supplier may be able to work with the client to develop the appropriate system, but this depends much on the skills, resources, and attitude of the supplier.

2. Management-inclusive packages-this approach offers the advantage of management tailored to the systems, and in some cases, some form of production target or even guarantee. The supplier will usually therefore have to take greater care to ensure the system fits the local requirements. However, this approach can be relatively expensive, and may involve the client in longer-term contractual commitments which may work to the client's disadvantage. The buyer should be careful to check the competence of the actual management team proposed, and their ability to work in the local conditions. It is also important to consider how dependent the system is on the continued use of outside assistance - can local staff and resources be used? What about training?

3. Financed packages-there are two main forms; the first, where the supplier can offer financing, usually through a commercial lender or through export credit for some or all of the package; or the second where the supplier establishes a joint-venture operation with the client, sharing the risks and returns of the enterprise. In the first approach, there may be a requirement that the supplier manage the project or operate a service contract, as part of the security of the project. The approach is then generally similar to that of the previous case.

The second approach should offer the advantage of ensuring that the supplier is also interested in efficient and profitable operation this route is sometimes favoured by specialist groups with expertise and access to capital, but lacking access to sites or other critical resources. However, the use of an expensive service contract can sometimes reduce or even eliminate the specialist partner's risk, and hence their motivation for success. Obviously, the client will have to be even more careful than in other cases about determining the financial and managerial strength of their partner.

Perhaps one most difficult tasks facing a new entrant to the aquaculture industry is that of finding out exactly what typical operating or performance standards might be expected of any proposed system, and what the risks might be in choosing a particular package. For larger projects particularly, it is well worthwhile employing an independent professional advisor to review detailed aspects of any package proposal.

Equipment: the judicious use of equipment can certainly be a good way of exploring the potential of high technology and of adapting it for your needs in many cases, a relatively cheap and simple form of aquaculture can be improved significantly by the use of specific, often quite simple items of equipment -aerators in ponds, pumps to supplement water supply, screens or filters to remove contaminants from incoming water, simple mechanical lifts to assist harvesting, etc. In other cases, eg tanks in hatcheries, cages for ongrowing the equipment represents the major part of the production system. In only a few cases in fact can equipment be defined as high-technology - eg electronic or computerised alarms or controls, water treatment systems, egg counting and sorting machines, etc-these are usually only used for specialised duties.

Probably the most important factors in using equipment successfully are:

-  to be clear about what you want, what purpose the equipment has to serve, and in what conditions the equipment must operate.

-  to choose equipment which is suited to the equipment of the farm, can be run by farm staff, and will withstand local operating conditions.

-  to use reliable manufacturer, preferably one with local service capacity, and a proven record of use in conditions similar to yours.

-  to be as clear as possible about the capital costs of the fully installed equipment, its operating and maintenance costs, its likely lifespan, and the probable effects on the yields running costs of the project as a whole.

-  to install it properly, to use the correct operating procedures, and to monitor its use.

Normally, you will find quite a wide range of suppliers for the commonly used items, such as tanks nets, cages, feeders, etc. In addition many other items, such as pipes, valves, pumps, air blowers, air conditioners, forklifts, hoists etc. are supplied through standard outlets, ie not as specialised aquaculture equipment. While the former supplier are often specialised in aquaculture, and develop their products specifically for the sector, they may lack the wider resources, and sometimes the technical backup, offered by larger general suppliers. On the other hand, these more general suppliers, unless specifically committed to the industry, may not be well enough acquainted with aquaculture and its requirements to offer the best technical guidance.

DEVELOPING VALUE

Increasingly, adding value into aquaculture products is recognised as a vital and necessary component of the production process. Whereas formerly producers could rely upon their chosen combination of production system technology to produce a sufficiently high value product it has become practice to attempt to add value wherever possible in the production process. Some explanation for his lies within the increased levels of competition within the international aquaculture sector. More rapid diffusion of technical innovations mean that few producers now can realistically expect to identify, develop and maintain a technically based comparative advantage for long. There is a constant need to innovate or at least adopt new technical standards.

To some extent the need to add value is dependent upon the existing value realised within the production process. In general it can be expected that more value added will tend to increase profitability. But this in turn will tend to increase the number of players in the sector and hence production of that species is likely to rise and ultimately reduce market prices through the increased supply. This in itself then generates more pressure to add yet further value.

Adding value may be done in a variety of different ways, and not all require the incorporation of technology. Indeed it should be remembered that good husbandry practice is perhaps the most effective way in which value might be added. The increased speed of technical progress and its availability may mean that comparative advantages are more likely to be realised and be sustained through good husbandry practice.

The objective behind adding value should always be to the driving factor in any decision as to how any value might be added. Clearly there is little point in adding value unless this can be reflected in improved profitability. However this does necessarily mean that the addition of value will automatically bring about an increase in market prices. In some instances, especially those where competition is intense, adding value will serve simply to differentiate the output of one producer from that of another. Although, in the longer term it may prove possible to capitalise upon this product differentiation, to generate a larger market share.

In an increasingly cost conscious marketing environment the temptation to add value simply through increasing inputs, such as improved feeds, to the production process should also be avoided unless this is reflected in market gains. To compete within the wider market for foods, aquaculture products cannot afford the needless incorporation of additional inputs.

Perhaps the most important consideration determining the addition of value is whether the market will perceive, and itself place some value on, nay changes made. If this is not the case them the wisdom of so doing must be questioned; although longer strategic considerations also will need to be brought into the equation.

The whole notion of what constitutes perceived value must be recognised to be a dynamic phenomenon. Consumer preferences are in a state of permanent flux and are varied within individual market segments. Thus in some target markets it maybe possible to add value by incorporating further processing of the finished product, for example by producing a fillet product rather than a whole fish. However other consumers may prefer that the fillets be available in a modified atmosphere pack, whilst others still might place greater value on a gutted head-on product. This demands that the producer remains in constant touch with the market to identify the nature and composition of any changes in customer wants.

As was implicit in the above examples, it should also be noted that value may be perceived in the intangible features of the product. For example the packaging will additional benefits of convenience, easier storage etc. But increasingly so too may consumers perceive value in the inputs to their prospective purchase. The environmental impact products is becoming a more important consideration within the purchase decision making process an cultured fish is an easily identifiable area for concern. Adding value may thus increasingly assume connotations of environmentally friendly production and other processes deemed to be consumer acceptable. However obscure, or ill-founded, these perceptions may appear to be, it must be remembered that they command the final dollar vote.

WHAT OF THE FUTURE?

Many of the more spectacular high-technology systems are still only under evaluation, in many cases a number of ‘teaching problems’ exist - unfortunately these often reflect the difference between what the promoters hoped could be done, and what the stock was prepared to accept! Indeed, systems such intensive recycle units have appeared, died out and reappeared again many times in the last twenty years - often with very little improvement during intervening period.

However, the aquaculture community is now at least more sceptical of wilder claims, more aware of the risks, and most importantly, more able to direct technical development towards the most useful and productive goals. We can therefore expect to see more substantial technical development in the future, based on more realistic, practical expectations. By using careful assessment, asking the right questions, and supporting and working with good and reliable suppliers, the aquaculturist can play an important part in making sure the industry has the technology it needs for the future.