November/December – 1998
Story Title: Tailormade Aquaponics
Author: Steven Carruthers
Aquaponics, the combination of aquaculture and hydroponics, is an emerging technology. It offers the hope of high returns for investors, and a means to augment wild fish populations that have been depleted. STEVEN CARRUTHERS reports on.
If you ever wanted to become enthused about the future of aquaponics in Australia, you could do a lot worse than talk to Port Stephens (NSW) grower, Nick Arena. With the commercial development of aquaponic technologies still in its infancy, Nick is convinced that his combined barramundi and lettuce facility will provide a ‘blueprint’ for others to follow.
Aquaponics is the marriage of aquaculture and hydroponic technologies, where nutrient-rich, organic waste water from fresh-water fish farming is re-used to grow hydroponic crops. Plants take up the organic nutrients and act as a natural filter of the waste water. Like all farming, aquaponics involves a series of trade-offs between different considerations, and the skill applied to this juggling act determines the level of success.
Nick and his fellow shareholders are newcomers to aquaponic farming. It all began 2 years ago, when a group of recreational fishing friends became concerned about the steady decline in wild fish populations along the NSW coast. A chance remark to another friend, a marine biologist with a background in barramundi farming, led to the formation of Tailormade Fish Farms. Among its 12 shareholders are two builders, an electrician, marketing manager, project engineer, and marine biologist. The group volunteered their labour and skills to build the necessary infrastructure, to meet the stringent requirements for a barramundi farming permit. Four members of the group are now employed full-time on the farm. The group’s champion, Nick Arena, quit his successful renovation business in Sydney to manage the day-to-day operation of the facility.
Tailormade Fish Farms is situated on 43 acres of flat, sandy soil, sheltered by stabilised sandhills and tree-lined windbreaks. Other physical attributes include a warm coastal climate and good quality fresh water, as well as salty bore water. Although the price of the property exceeded their budget, considerable savings were made in other areas. The property, a former rose farm, came with existing electricity, bore and water pumping equipment, 5 water storage tanks with a capacity of 30,000 litres each, several igloo frames, and an 800 square metre concrete slab, among other useful farm materials and equipment.
In keeping with the NSW Fisheries Barramundi Farming Policy, the site is above the 100-year flood level, and more than 500 metres away from natural waterways. In accordance with Environmental Protection Authority (EPA) regulations, the facility features a network of retaining walls, to hold culture water in the event of an accident. Fortuitously, pre-existing retaining walls were already in place to contain nutrient run-off, from the days when the property was used to grow roses. The walls are subdivided over 10 acres, another saving for the group.
Barramundi is an exotic fish species in NSW and its importation into the state has associated risks. NSW Fisheries has four areas of concern which must be addressed before a barramundi permit will be issued. These are: the prevention of fish escape, control of and disposal of effluent, prevention of disease transfer, and the provision of a sound business plan.
In relation to the control and disposal of effluent, the group submitted a plan to adopt hydroponic technology to grow leafy salad vegetables and herbs for the consumer market, a plan that found favour with the EPA, NSW Fisheries and the Local Shire Council.
“Satisfying the needs of Council was probably our hardest hurdle,” explained Nick.
Not all Shires regard fish-farming as a green industry. In an area noted for its pristine coastal and inland water environs, Shire Councillors were extra cautious the venture met stringent environmental standards. All new aquaculture ventures require an Environmental Impact Statement (EIS)
“It’s costly and a lot of hard work, but we were able to put together our own EIS, without the need for a consultant,” commented Nick.
The recirculating aquaculture facility takes advantage of the pre-existing concrete slab to support 10 rectangular rearing tanks, constructed of fibreglass to the group’s specifications. A square-framed hothouse has been erected over the tanks to help maintain temperatures at night and during the colder months of the year. Each rearing tank has a capacity of 30,000 litres, with an additional 5000 litres held in a settling tank. In the event of a problem, rearing tanks are isolated from each other.
At this early stage of development, only one tank is fully operational, rearing some 30,000 barramundi fingerlings. At full capacity, the facility is expected to rear 50,000 fish.
A second tank is used to trial golden perch (Macquaria ambigua). The species has good market acceptance and is consistently in the highest price bracket at the market, but the group have found the fish too finicky – it refuses to take fish pellets and other artificial feed. It is also a slow grower when compared to barramundi.
“A barramundi is actually pleased to see you in the morning,” commented Nick. “To get a look at the golden perch, you have to sneak up on it.”
There seems to be three basic conventions for both aquaculture and hydroponic technologies – balance, stability and control – and the one factor that stands out as being critical is the quality of water in the growing systems. Water quality will determine the quantity and quality of production and ultimately the profitability of the operation. At Tailormade Fish Farms, each rearing tank has an independent water treatment system, to ensure those profits in the event of a problem.
The largest load on the filtration system are suspended organic substances such as small particles of uneaten feed and faecal wastes, and inorganic materials such as suspended clay and sand. The presence of organic material increases bacterial activity, which will reduce dissolved oxygen levels and increase CO2 and ammonia; and suspended inorganic materials, especially sand, can damage fish gills.
The bore water is drawn from the settling tank, then passed through a biofilter to remove all particulates down to 20 microns. The biofilter is backwashed at regular intervals to remove particulate matter.
Once filtered, the water is pumped to a protein skimmer to remove surface active dissolved organics.The protein skimmer uses a water pump and venturi to inject large volumes of water mixed with air into a column of water. The fine bubbles created by the venturi swirl to the surface as a foam, which includes dissolved organics as well as fine particulate matter.
Sterilisation is achieved using ozone, which is injected into the venturi line at the rate of 6 gm/hr. The ozone and venturi effect also aerates the culture system. Treated water is then piped to the rearing tank, where it is allowed to spill over to break the surface water tension, further assisting in aeration.
Nutrient-rich waste water is pumped to a central wastewater tank (30,000 litres), where it is treated with ozone before leaving the aquaculture facility for the hydroponic farm.
According to Nick, temperature has the greatest effect on the physiology of fish, because they are temperature conformers. That is, their body temperature almost matches the water temperature. Water temperature can have a significant effect on respiration, food intake, digestion, growth and behaviour, through its effect on the metabolic rate in fish. It can also affect the amount of oxygen that can be dissolved in water. That is, warm waters hold less oxygen than cold water.
Barramundi are tropical fish and require high water temperatures, between 24-32°C. The rearing tank is maintained at 27°C, with a 20 variance between day and night. Maintaining the temperature is assisted by the hothouse environment, and small commercial water heaters (3kW) which are used during the night.
One of the major cost factors for any aquaponic venture is electricity to power pumps, water treatment equipment, heaters and cool rooms, as well as many kinds of tools and instruments used in the day-to-day running of the farm. Nick forecasts an annual electricity consumption cost of around $32,000, once the venture is running at full capacity.
From import to harvest, the growth cycle of barramundi is around 6 months. The first shipment of fingerlings arrived at Tailormade Fish Farms 5 weeks earlier, measuring 3cm and weighing 0.4 grams. At the time of my visit, the average fish length was 7cm (1.4gm).
“The slow growth period is that early stage,” commented Nick.
Fingerlings are fed high-protein pellets, the size of which changes with the size of the fish. Although automatic feeders are available, fingerlings are hand fed to allow the group to closely monitor fish development.
“If the fish are off their food, they’ll soon let your know,” commented Nick.
Fingerlings are fed four times daily with the last feed around 8pm.
According to the projected budget, the feed cost per 13,000kg of fish is around $20,000 over the 6-month growth cycle.
“If you are using automatic feeders, and the fish are off their food, then you are throwing away food that’s not going to be eaten,” added Nick.
Barramundi are normally harvested between 300 to 500 grams and sold to restaurants as plate-size individuals. Prior to sale, the fish are purged with salt water, to remove the ‘pellet taste’.
“You are what you eat,” commented Nick.
Purging refers to a process of cleansing fish for market by allowing fish to evacuate their stomach contents. The normal process is to maintain the fish in a tank for a few days with flow-through of water. The process improves flavour and assists in keeping pollution to low levels during live transport.
With pre-orders from several local seafood restaurants, the group expect to harvest their first barramundi at 350 grams, however the bulk of fish is expected to go to nearby fish markets. The marketing approach means that cash returns will occur in less than a year and a high price per kilogram should be realised.
A major concern for NSW Fisheries is the possibility of introducing disease along with imported barramundi. There are two known diseases of barramundi that are not considered to be caused by ‘normal’ environmentally derived microflora and not considered widespread in many host fishes. These are Lymphocystis disease, and the group of larval mortalities associated with brain and retinal vacuolation caused by encephalitis virus.
Barramundi Encephalitis Virus (BEV) in particular is highly virulent and causes heavy mortalities in infected barramundi up to 3 weeks of age. To minimise the risk of this virus entering the State, shipments of barramundi fingerlings must be accompanied by a BEV clearance certificate. No barramundi fingerlings are allowed import under 42 days of age.
Although barramundi are less susceptible to disease than many other fish species, stress from poor water conditions, poor fish handling, or equipment failure, can lead to other health problems. To aid in the early warning of potential stress problems, silver perch (Bidyanus bidyanus) are used as a ‘canary’ fish, to ensure there is nothing sinister in the aquaculture environment.
Plankton blooms, and their management, are part of any aquaculture environment. Uneaten feed and fish by-products can lead to an explosion in phytoplanktons, and too many planktons or a bright green scum on the surface, can indicate that more serious problems lie ahead. Through the process of photosynthesis, phytoplanktons produce oxygen (O2) during the day and carbon dioxide (CO2) at night. Unfortunately, carbon dioxide has an affinity with water and doesn’t leave voluntarily. Unless properly managed, excessive CO2 levels will form carbonic acid. Aerating the pond by breaking the surface tension, exposes the water to the atmosphere, gases off the CO2, and allows the water to take on oxygen.
“Too much sunlight is our biggest problem – the algae goes berserk,” explains Nick.
Corrugated iron and shadecloth are used over the rearing tanks to help control the planktons.
There are no surprises in the hydroponic growing system, which consists of 20 NFT tables, using Panda gully 18 metres in length. The only unusual aspect is the high flow rate, of 2.5 litre per minute.
The system has a capacity of 11,000 plants with the tables paired inside pre-existing igloo frames, and exposed to full sunlight. One igloo is covered and used to trial basil and fancy lettuce varieties. Another 20 tables are under construction, which will double the capacity of the facility.
Nutrient-rich waste water is piped down from the waste water storage tank to a settling tank (5000 litres), where it is diluted with fresh water, if required. With insufficient organic nutrients to feed the first three lettuce crops, the feeding regime was supplemented with inorganic nutrients, a standard commercial lettuce formula from Accent Hydroponics. The system is maintained between cF 18 and cF 20, and the pH between 5.8 and 7.0.
At the time of writing, there was sufficient effluent to meet the demands of a mature lettuce crop, although wide fluctuations in pH have been observed. Excessive ammonia is thought to be responsible, although the lettuce appear to be unaffected by the swings.
The main lettuce varieties include red and green oak, butter, baby cos and curly endive, which all have strong colouring from the open culture. Shorter growing periods have also been observed. The bulk of fresh produce is marketed through the nearby farmers’ market.
Although plants take up the organic nutrients and act as a natural filter to the waste water, it is not returned to the aquaculture facility. At a commercial level, this is not an option, especially if pesticides are used to control insects.
“Anything that kills bugs will kill fish,” explains the group’s hydroponic manager, Peter Nicholson. “When I do spray, it’s early in the morning when it is dead calm,” he adds
Commercial aquaponic ventures can produce a good financial return, but their success is generally underpinned by careful planning and good management practices.
“The technology is there, but a lot of money can be wasted on poor planning,” Nick warns.
It is unlikely barramundi fillets will reach the export table in the near future. According to the Australian Barramundi Growers Association, barramundi is imported from South-East Asia at around $5-$6 per kilogram, compared with $10-$12 a kilogram to produce locally. A major constraint for locally grown barramundi is the high production costs. The latest estimates for on-farm production costs are in the range $5-$7.50 a kilogram for a plate sized product – the major on-farm variable cost is feed, which accounts for around 30%-50% of on-farm costs (Barlow, Williams & Rimmer, 1996).
From a conservation aspect, the depletion of Australia’s wild barramundi stocks signals two future roles for ventures such as Tailormade Fish Farms. It can supply meat on a sustainable basis, and serve as a source for genetic material to augment wild barramundi populations that have been depleted.
From a hydroponic aspect, the cost of commercial plant nutrients is almost negligible, which historically is a significant on-farm cost in hydroponic production. By growing short-term crops such as lettuce, hydroponic technologies bring to this aquaponic venture a regular cash flow.
With economic conditions becoming harder for Australian farmers over recent years, there is increasing pressure to find alternative areas of production. Aquaponic ventures offer some opportunities, however, a suitable financial return demands good planning, management skills and knowledge.
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