Friday, April 7, 2017

The Control Of White Feces Syndrome In Vannamei Shrimp Aquaculture
















Supito*, Arif Gunarso and Ita Rizkiyanti

Main Center for Brackhiswater Aquaculture Develompmet. Jepara Central java

White feces disease on vannamei shrimp farming has currently lower productivity. Exploration study on infected farms to determine the cause and control techniques and treatments have been done to prevent infectious of white feces diseases.

The method of exploration study has done by observing the water quality include the content of organic matter (TOM); total bacteria and vibrio; the stability of the plankton and identification species of bacteria in diseased shrimp. Control measures carried out by the improvement of water quality by controlling the organic matter, maintain the stability of the plankton and application of probiotics to balance C,N,P ratio. Fasting techniques and applications of natural antibiotic feed additive from garlic extract (alicyn) and vitamins to increase the effectiveness of the material to the digestive shrimp.

The results showed that shrimp white feces disease there are several in the intestinum are species of bacteria Vibrio alginolyticus, Vibrio parahaemolyticus and Vibrio vulnificus. Pond water contains vibrio bacteria dominance more than 12% of the total bacteria. Tottal and organic matter (TOM) more than 250 ppm. Fasting technique, alicyn and vitamins application, controlling vibrio dominance less than 10% with the application probiotics well as the disposal of sludge pond bottom and water changes to reduce content of organic matter could be for prevent disease. Ponds production be maintained on the survival rate of > 70% with average daily growth rate (ADG) 0.11-0.25 g.

- World Aquaculture Society

Friday, March 31, 2017

The promise of In-Pond Raceway Systems


Fig. 1: Illustrative representation of an IPRS and images of fixed and floating IPRS installed at commercial catfish farms in Alabama.

As world population and seafood demand continue to increase, intensification of aquaculture is unavoidable while fisheries resources, land and freshwater become more limited in many regions. The increase in global trade of aquaculture products also requires more competitive and efficient production approaches by farmers and processors to deliver high quality products to meet global demand.

Freshwater pond aquaculture, in particular, will be further challenged to intensify production, while using less water and zeroing effluents, as government agencies continues to impose more regulation on water uptake and effluent discharge. In addition, consumer awareness on the origin, safety and sustainability of food continues to increase and has driven wholesalers and retailers to impose a cascade of demands for certification of aquaculture products that farmers and processors must meet.

Aquaculture enterprises must move towards more intense and sustainable production strategies, and require more efficient use of water, feed, labor, energy and other resources to maintain high quality products at competitive prices compared to other fish, seafood and animal meats available to consumers.

Aquaculturists are always looking for ways to increase fish yield, as they often associate productivity with increased business competitiveness and profits. However, production in pond aquaculture is limited by the amount of wastes (mainly decaying phytoplankton and metabolic and fecal residues of fish) the biota in a pond can assimilate while maintaining satisfactory water quality for growth and health of fish.

Dissolved oxygen is typically the first limiting factor to fish yield in ponds. Early morning dissolved oxygen in pond water has an inverse relationship to feeding rate, phytoplankton abundance and fish biomass. Pond aeration provides additional oxygen, improves water circulation, reduces water stratification and accelerates the decomposition of wastes. Supplemental aeration, thus, is a worldwide tool farmers use to improve water quality, while increasing feeding rate and fish yield from ponds.

However, in ponds with no water exchange, despite all the aeration that can be supplied, ammonia poisoning is generally considered the second limiting factor of production. Total ammonia concentration increases proportionally to the amount of organic wastes entering the ponds. Thus, feeding rate and decay of dead phytoplankton has a direct relationship to total ammonia levels in pond water.

With more aeration, farmers can stock more fish and add more feed to a pond, targeting higher fish yields. However, this can lead to an excess of organic wastes and nutrients, which favors growth of dense phytoplankton blooms in the ponds. Intense photosynthesis by microalgae can cause pond water pH to reach values above 9.0 at noon and afternoon hours, which increases the risk of unionized ammonia toxicity in heavily fed ponds.

For this reason, in addition to aeration, farmers need to set upper limits to feeding rates, monitor afternoon ammonia and pH levels and apply strategies to prevent excessive phytoplankton. Since water exchange is becoming more restricted in freshwater pond aquaculture, updated pond management and production strategies, in addition to just increasing aeration, are needed to improve water quality to further increase fish yield in heavily fed ponds.

In-Pond Raceway System (IPRS)
The In-Pond Raceway System (IPRS) is a promising strategy to further increase fish yield in static ponds. Instead of growing fish free in the pond, in the IPRS fish are confined at high densities in floating or fixed raceways (Figs. 1 and 2). Water circulation and aeration is continuously provided to each raceway, maintaining adequate and safe oxygen levels in the growing cells, independently of the oxygen status in the pond.

The raceways seldom exceed 3 percent of total pond surface area. The IPRS was first conceived and developed at the School of Fisheries, Aquaculture and Aquatic Science – Auburn University (SFAAS-AU) in the early 1990s. Initially, units were small and constructed with wooden panels. Since then, researchers at SFAAS-AU have conducted several experimental- and commercial-scale evaluations to understanding the potential, advantages and limitations of farming catfish in IPRS compared to conventional or highly aerated catfish ponds. Such evaluations also contributed to improve the design, construction and operation of IPRS, culminating with the semi-commercial size floating raceways made with a metallic frame lined with high density polyethylene (HDPE) and a more efficient airlift device to aerate and circulate the water through the raceways and pond.

Results from the semi-commercial scale evaluation of IPRS at Auburn University
A four-year project is in progress at Auburn University to refine IPRS management protocols, improve design and operational efficiency and assess economic feasibility of semi-commercial scale IPRS to produce catfish. The first year’s goal was to demonstrate that market size catfish (average weight of at least 680 g and minimum weight of 450 g) could be produced in a growing period of 8 to 10 months, at a yield twice the average yield of 7,800 kg/ha attained in conventional catfish ponds in Alabama.

Four 0.4-ha earthen ponds were each equipped with an IPRS (Figure 2). The IPRS units in B1 and B2 were 63.6 m3 in volume (4.9 m wide, 10.7 m long and 1.2 m water depth), while in B3 and B4 smaller units of 45.3 m3 were used (3.1 m wide; 12.2 m long and 1.2 m water depth). Each IPRS pond was supplied with 2.5 HP of aeration and water circulation effected by two regenerative air blowers.

One 1.5-HP blower propelled the air lift apparatus at the entrance of the IPRS raceway, while another 1.0-HP blower propelled the air lift apparatus of the water moving unit installed at a pond corner diagonally opposite from the IPRS unit. A 55-m long and 1.5 m high baffle curtain, made of woven plastic fiber, was installed diagonally inside each pond to direct the water circulation around the entire pond.
Fig. 2: Aerial view of the four B-ponds housing the IPRS units. The raceways in ponds B1 and B2 (63.6 m3) were larger and occupy 1.3 percent of total pond area, while in ponds B3 and B4 raceways were 45.4 m3 each and covered 0.9 percent of pond area. In each pond, a curtain baffle was assembled extending diagonally from one of the end corners of each raceway towards the opposite corner of the pond, where another water-moving device was located, to promote a more effective water circulation in the ponds, indicated by the yellow arrows in the photo (original photo by David Cline). A detailed view of the floating raceway and the water-moving device in Pond B3 is shown in the images to the right above.

The raceways were stocked with 41-g hybrid catfish fingerlings (female channel catfish Ictalurus punctatus x male blue catfish I. furcatus) on March 22, 2016. Fish were fed 32 percent crude protein commercial floating catfish pellets (4 to 6 mm) once or twice a day, depending upon water temperature. Each feeding event lasted for 3 to 5 minutes, until near momentary satiation of fish.

Dissolved oxygen, temperature and other pond water parameters were regularly monitored. Catfish reached market size in early December 2016. Raceways were harvested after nearly 270 days of culture (Figure 3), and fish were sold to an Alabama catfish processor.Fig. 3: Harvest of fish from the IPRS was accomplished by fitting a live car at the end of the raceway, removing the end screen of the raceway and pushing a bar grader inside the raceway to corral fish into the live car. The live car with all fish was then pulled to the edge of the pond. With a crane and a basket (boom), fish were loaded into the hauling tanks and transported live to the processing plant.

Production, feeding rate and water quality
Catfish yield ranged from 13,660 to 16,500 kg/ha and exceeded the target value of 15,600 kg/ha in ponds B1 and B2. Average feeding rates ranged from 70 to 90 kg/ha/day. Maximum feeding rates of 300 to 350 kg/ha/day was reached in all the ponds early fall (late September, in USA), when fish already weighed more than 550 g. Dissolved oxygen concentrations were often low at early morning hours during summer months in all the ponds.

However, inside the raceways oxygen was seldom below 3 mg/L. Dissolved oxygen close to 2 mg/L inside the raceways were registered a few days, when dissolved oxygen in the open pond water declined to values around 1 mg/Liter, as can be seen in Figure 4 for pond B3, the pond that had the lowest oxygen levels.

Other parameters of water quality are summarized in Table 1. Maximum levels of total ammonia nitrogen (TAN) were 1.8 mg/L in pond B4 and as high as 8.0 mg/L in Pond B2. Fish were exposed to the highest concentration of unionized ammonia (N-NH3 = 1.66 mg/L) in pond B1, since the afternoon water pH in that pond often reached values around 9.0 and 9.5 due to the presence of dense phytoplankton blooms.

In pond B2, despite the high total ammonia levels, toxic ammonia levels were not a concern at all, since phytoplankton blooms did not become established in that pond to cause pH to increase (afternoon pH ranged from 7.0 to 8.0 in pond B1). Nitrite concentration in all ponds remained well below the 7 mg/L LC50-96h determined for channel catfish.

Nonetheless, pond preparation protocol included the application of salt (NaCl) to prevent nitrite toxicity of fish. Chloride levels in pond water ranged from 100 to 140 ppm for all ponds, except for water in B1, which had 300 ppm of chloride.Fig. 4: Illustration of the early morning dissolved oxygen concentration in the pond (blue area) and inside the raceway (green area) in pond B3. The green area above the blue area indicates how much oxygen the aeration device added to the water at the entrance of the raceway, keeping dissolved oxygen levels inside the raceway often above 3 mg/L (minimum desired level) and seldom below 2 mg/L, even when pond DO approached values close to 1 mg/L.

By: Fernando Kubitza, Ph.D. Jesse A. Chappell, Ph.D. Terrill R. Hanson, Ph.D. and Esau Arana

Wednesday, February 22, 2017

How does rainfall affect shrimp pond water parameters? - Part 2

You can read Part 1 of this article in following link:
How does rainfall affect shrimp pond water parameters? - Part 1

Plankton crash
When temperature, light, salinity, pH and alkalinity change suddenly, plankton activity will reduce and maylead to a plankton crash usually within two days. The thicker the bloom, the faster the plankton will crash. We can observe this via changes in water colour and pH, or when the afternoon pH is lower or the same as the morning pH. This means that plankton is crashing or is in the process of crashing, even if the water is still green in colour. Dead
plankton is still green and may still provide some green colour in the pond.

Dead phytoplankton brings about low DO as there is no oxygen production and oxygen is used for bacterial action. This means that if DO in the afternoon is 6-7 ppm it may drop to only 2-3 ppm. When the dead phytoplankton of which 90% will accumulate at the pond bottom starts to decompose, they will start to compete for oxygen. If the farmer sees cloudy water, foam at the pond surface, bubbles with a long trail and plankton flcculating, this means that the plankton has crashed.

Shrimp moulting
Rain causes pH to drop drastically, as the pH of rainwater is usually lower than the pond water; slowing of plankton activity also causes the pH to drop. Under such conditions moulting occurs. When moulting, shrimp need more space, twice as much oxygen and increased mineral levels. However, conditions during the rains are not favourable for moulting; moulted shrimp have soft shell, and succumb easily to infection and mortality. Moreover, cannibalism of dead shrimp makes it diffiult for the farmer to detect the dead shrimp. What we will observe is a reduction in feed and lower ADG.

Accumulation of organic matter
During rainy periods, shrimp will not feed normally, but the farmer continues to feed the usual amount of feed thus leading to overfeeding. Phytoplankton activity will also drop as discussed previously. Bacterial action will also slow down, allowing organic matter to accumulate on the pond bottom. This means that a time bomb is ticking as the bacterial population will suddenly bloom when the temperature rises as there is excess organic load
in the pond. Usually the pathogenic bacteria will be the ones which bloom because they are usually hardier and can withstand harsher conditions. They also tend to grow much faster than benefiial bacteria.

Why is there a tendency to overfeed? This is because farmers tend to check feed in the check tray only. Feed in the check tray is easily accessible by bigger and stronger shrimp. Normally, bigger shrimp are always being surrounded by other shrimp and the former are not allowed to feed peacefully in the check tray. However, during the rainy period when most of the shrimp do not have good appetite, these bigger shrimp now have an opportunity to eat and fiish off all the feed in the check tray. As the shrimp gut is fairly short and open, they are quite capable of eating non-stop until the feed is finished. This will give a false picture of the current feeding habits of the shrimp in the pond.Farmers will think that they need to increase feed whereas the opposite is true. The bigger shrimp will also tend to eat more and faster because of the strong smell of the feed in the check tray but the rest of the feed that is spread out in the pond will not smell as strong and may not be as attractive to the shrimp. This will lead to the accumulation of excess organic matter in the pond.

Combined effects
The overall effect of excessive rainfall is shrimp mortality due to H2S poisoning, soft shell issues and accumulation of organic matter. The farmer needs to understand the big picture of how rainfall can affect the various parameters in a pond.

Recommended best practices
Ideally, farmers should use available technology and predictive weather forecasts. Some weather forecast websites are weather.com and accuweather.com. If they learn to predict the weather in the next few days of culture, they will be better prepared for any eventualities. If there is going to be rain in the next two days, pond preparation should include the application of Pond Dtox (Novozymes, USA)- a bacteria product that can neutralise hydrogen sulphide, a day before or just before it starts raining.

Further to this, the following measures are recommended.
• Always make sure that the oxygen levels are 20% more than required. Switch on the aerators. All aerators should be running when it is raining.
• If there is heavy rain, allow the excess rain water to overflow from the surface.
• Assign a worker to apply lime on the bund as a usual practice during good weather. Then when it rains, the lime will leach into the water helping to maintain alkalinity.
• Assign a worker to check the water pH during rainfall. If the pH falls, apply lime.
• Stop feeding during rainy conditions.
• Mix Vitamin C and salt (minerals) with feed before or after the rains. The dosage is 5 g/kg feed. Dilute 17x water (add 5 g of salt to 80 mL of water), mix into feed, allow to air dry, then feed the shrimp. This will allow the shrimp to obtain minerals from the feed if there is a drop in alkalinity in the water.
• Once the rain stops, it is recommended to apply a double dosage of Pond Plus (Novozymes, USA) to allow benefiial bacteria to fist colonise and then competitively exclude the pathogenic bacteria.

In summary, our advice to farmers is to be prepared during rainy periods as there are so many factors contributing to problems in the shrimp pond. Being aware and being prepared
are the fist steps to overcome the problems encountered during the rainy period. There are signs to watch out for and we need to read the signs correctly and take preventive and proactive action to minimise and prevent losses.

 Erin Tan

Tuesday, February 21, 2017

Mobile Aerator for Shrimp Farming

Farming shrimp for over 30 years, electricity is always a problem. Can’t believe mobile aerator really cut down on that needless cost.”

Shared by a shrimp farmer in Pintung, Taiwan, one of the mobile aerator users.

Why is mobile aerator so good?

Mobile distance: 100~150 meter


Electricity & Usage

Well, saving is earning, if you are tired of the repeatedly waste, and really want your shrimp to be competitive, email me right now. And in the end, a 30-sec youtube video of mobile aerator is below.

The most important 30 sec video for your shrimp and fish, Mobile Aerator
​​
Hans Chueh
International Sales
Website: 
http://www.mobilepondaerator.com/en/
WhatsApp: +886-972739805

Sunday, February 19, 2017

How does rainfall affect shrimp pond water parameters? - Part 1


Problems in shrimp farming usually occur during severe drought or heavy rainfall. Observations confim major losses occur mainly during periods of rainfall.

In the last two years, we have had droughts brought about by El Niño. The US Climate Prediction Center and the International Research Institute for Climate and Society have issued an announcement that there is a 60% chance of La Niña developing in the last quarter of 2016. In contrast to El Niño, with La Niña we will witness prolonged storms, heavy rainfall, heavier monsoons and severe winds resulting in more hurricanes and tropical
storms. What does it mean and how will it affect shrimp culture in South East Asia?

The most dangerous phenomenon that can affect shrimp culture can be attributed to rain. In general when farmers recalled when they encountered problems, it was more often during the monsoon seasons. Major losses occur mainly during the rainy season. In 2016, we had hot weather for the fist 6-7 months and now the rainy season is coming. The La Niña effect can usually last for 2-3 years. How will excessive rainfall affect shrimp pond water parameters?

Rain has very serious effects on shrimp culture. Effects on shrimp include cramping, loss of appetite and reduced feed consumption, shrimp parking at the side of bunds (2-3 days after
the rains) and black gills or dirty shrimp. From some observations and records, in south Thailand, shrimp mortality may range from only 2-3% to 50%. We gathered statistics and co-related the data to weather reports. There is no doubt that heavy rainfall can cause huge mortalities. However, the signs of impending mortality are usually minimal unless the farmer knows what to look for.

It is important that the farmer is aware of several direct and indirect effects of rain on water parameters in shrimp ponds. In this article, we discuss various direct and indirect effects of severe rainfall on shrimp culture (in no particular order) and elaborate in detail key points on how rainfall affects shrimp culture.

Direct and indirect effects
The direct effects on pond water are reduced temperature, oxygen, pH, alkalinity and salinity. Sound and wave disturbances increase, and rainwater flws from the bund into the pond.


The indirect effects are phytoplankton crash and organic material accumulation at pond bottom. There will be a sudden bloom in bacterial population after the water temperature returns back to normal. The agitation of the sludge layer exposes the anaerobic layer (black soil) and shrimp will be exposed to toxic hydrogen sulphide (H2S) gases

The results of these direct and indirect effects of rainfall are:
• Once all the above occur, oxygen is depleted and toxic gases such as H2S are released
• Recently moulted shrimp, which are weak become exposed to toxic gases and pathogens and succumb to infections
• Mortality may occur 2-3 days after a severe rainfall.


Temperature

During severe or prolonged rainfall and cloudy days, there will be less sunlight reaching the pond surface. Wind blowing across the surface of the pond can cause pond water temperature to drop by 2-3°C. The optimal pond water temperature should range

between 30-31°C. When temperatures drop 1°C, feed uptake by shrimp typically drops 5-10%. Thus, a drop of 3°C can cause feed uptake to drop up to 30%. When water temperatures drop, feed becomes less palatable and shrimp being cold blooded are affected by external water temperatures.

Shrimp activity also slows down. They will move less and tend to gather at the pond bottom. This will drastically increase shrimp density at the pond bottom. When this happens, being naturally competitive, shrimp will experience more stress as they compete for limited oxygen and space.

As the water surface is cooler following the rains, shrimp will move towards the warmer areas in the pond which unfortunately is usually the sludge area. Here the shrimp become exposed to toxic H2S gas and pathogenic bacteria. In these areas, oxygen levels are normally low, but during a rainy period, oxygen levels may drop to zero.

During normal temperature flctuations, microbial activity increases with increased temperature which accordingly reduces the organic load. Once there is a sudden drop in temperature, microbes also reduce their activity. This leads to the accumulation of more organic material in the pond. When temperatures rise again after a few days, there will be a sudden massive bacterial bloom as there is a lot of organic material for the microorganisms
to feed on. This will also take up more oxygen as the organic material is degraded in an already low oxygen situation.
Healthy Monodon Shrimp at DOC 173

Reduction in immunity
Heavy rainfall can cause pond water pH which usually is around pH 8, to drop. The pH of rain is usually around pH 6.5-7.0. Rain will directly drop pH by 0.3-1.5 in a very short period of time. This causes an immediate decrease in phytoplankton activity.

When pH drops, this causes the toxicity of H2S to increase. H2S is highly toxic at low pH. Shrimp will also be stimulated to moult under adverse conditions of low oxygen, increased density on pond bottom, increased H2S toxicity, low salinity and alkalinity. All these conditions combined increase the chances of moulted shrimp dying within 2-3 days after heavy rainfall. However, often this level of mortality is not noticed because the soft shelled dead shrimp are eaten by other shrimp.

Indirectly, farmers will only notice this occurrence when the average daily growth (ADG) is not improving. What is the key sign of this condition? When the feed uptake drops for 1-2 days after heavy rain, cannibalism occurs. Finally, the effect of the sudden pH shock results in lowered shrimp immunity.


Low dissolved oxygen
In a pond, there are usually two sources of dissolved oxygen (DO): from the aerators and from phytoplankton. During prolonged rainfall, plankton activity will slow down as there is
less sunlight available. This is undesirable; even though shrimp activity decreases due to the changes in temperature, its oxygen requirement is still high or as per normal. DO is supplied by aerators and if the water is not mixed properly, pond water stratifiation/stagnation will occur. The layer of freshwater (stratifiation) on the surface of the pond makes it diffiult for oxygen to dissolve into the rest of the water body. DO levels can drop from 4 ppm to 2 ppm and then to 1.5 ppm in half an hour if action is not taken immediately.

Salinity and alkalinity
With dilution of pond water with rainwater, both salinity and alkalinity levels drop. In order for shrimp to harden their shell, it needs suffiient minerals (alkalinity) in the water to do so. When salinity drops very quickly, the moulted shrimp will not harden their shell in the usual amount of time. Cannibalism will occur leading to infection of the weakened shrimp.


The plankton population will also drop due to the low light intensity, low salinity and low pH. These changes impact on the microbial population in the pond; benefiial bacteria tend to die
off allowing pathogenic bacteria to flurish. Also once alkalinity drops, pH will start to flctuate when the buffering capacity in the pond is reduced.


Sounds
The sound of raindrops tapping onto the surface of the water seems loud to us; imagine how deafening it is to the shrimp in the pond as water tends to amplify sounds. This causes a lot of stress to the shrimp. The shrimp will try to hide from the loud noises and retreat to the pond bottom. They are then exposed to low oxygen conditions, high densities, toxic gases and cold temperatures.

Waves caused by wind action
The sludge layer is covered by a thin oxygenated grey layer. Strong winds create waves which disturb this grey layer. This then exposes the anaerobic black sludge which releases various toxic gases such as H2S, ammonia, nitrite and methane. Water running off from the bund into the pond and flwing down to the pond bottom will also disturb areas with sludge accumulation and release toxic gases. On exposure to these toxic gases, shrimp become weaker and are prone to infections and diseases.

You can read Part 2 of this article in following link:
How does rainfall affect shrimp pond water parameters? - Part 2


 Erin Tan








Thursday, February 16, 2017

New era in shrimp farming

The innovative recirculation system in Brazil has zero sludge discharge into the environment, keeps parameters extremely stable and raises productivity.

Camanor Produtos Marinhos Ltda was set up in 1983 and today has two farms in the north and south of Brazil’s Rio Grande do Norte state. During Lallemand’s Aquaculture Meeting in Chennai, India in March, CEO, Werner Jost recounted the journey of the farm from an annual production of only 50 tonnes of shrimp until 1991 to 500 tonnes annually. In 2013, the farm began to use AquaScience, an innovative recirculation system, developed by a partner Luiz Henrique S Peregrino which pushed productivity in the farm in the south to 48 tonnes/ha whereas the traditional ponds continue to produce 1.5 tonnes/year.

“We are a dynamic team of three partners and we can quickly change decisions. For ten years, we had a production of 50 tonnes of shrimp annually. This was our lost decade without post larvae supply, feed or knowledge. Then we started a vannamei shrimp hatchery called Aquatec, now with 4 billion post larvae/ year, the first commercial hatchery in Brazil. Our big break was when the Brazilian real was devalued and we could export to France’s shrimp market. Production expanded to 5,000 tonnes in 2011. This came from three farms, the largest with 580 ha,” said Jost.

“In 2008, the real appreciated which made it impossible to sell into Europe. We had to restructure for the local market. We were also hit by the white spot syndrome virus (WSSV) in 2011 with mortality from 90-95%. Years before we had been studying the Asian concept of small lined ponds stocking 100 PL/m2 but we lost the crops at 15 to 45 days of culture. Despite changing designs and protocols, we lost 10 cycles over two years. We then moved to this AquaScience model.”we lost the crops at 15 to 45 days of culture. Despite changing designs and protocols, we lost 10 cycles over two years. We then moved to this AquaScience model.”

AquaScience
In this model, production ponds are 3,000-4,000 m2 and HDPE lined, with a central drain for water recirculation. The water recycles for 100-120 days and is then pumped out into a reservoir after each harvest and channelled back after pond cleaning. The farm is in its 7th cycle of reusing the water.

“The important aspect of AquaScience is zero sludge discharge. It is important that we do not discharge waste into the environment. Today we have 25 ha of productive ponds following this model and in a second phase, we will add another 25 ha of ponds. Soon we will have 50 ha of production ponds and 30 ha
of channels, tilapia ponds and recirculation area.

Jost emphasised that the system is special in that the water parameters are extremely stable. “ “Fluctuations of dissolved oxygen at only 0.5mg/L and 0.3 for pH over 24 hours keep away pathogens. Pond water temperature is controlled at 27-28°C with shading. Pathogens are present as the system is not totally closed and WSSV although present, does not kill shrimp. Solid waste goes to ponds holding tilapia, which feeds on the biofloc and clean water is recycled back to the shrimp ponds.

“With our first successful cycle in 2013, we were able to produce 10 tonnes/ha
of 12 g shrimp at 90% survival at a stocking density of 100 PL/m2. In February 2015, we increased this to 48.5 tonnes/ha/cycle of 22 g shrimp. Stocking density was 230 PL/m2 and survival was 95%. We target 55-60 tonnes/ha/ cycle in 2016. In terms of costs and revenues, our breakeven size
is 8 g. This means AquaScience needs to produce 20 g size to get 50% gross margins. We have to keep to this size as the market cannot absorb large quantities of larger shrimp,” added Jost.

“AquaScience is not only about technology; it is also an organisation for the maintenance of equipment and to effectively manage risks. It cannot be without electricity for more than 15 minutes. We need to design the right systems with four layers: electricity from the grid, local generators, central power station
and finally a mobile generator. “In the next three years, the target is 1,900 tonnes in 2016, 5,000 tonnes in 2017 and 9,000 tonnes by 2019. With a nursery system, we can increase to 4 cycles per year and by working on genetically improved shrimp for faster growth from the current 1.5 to 2 g/week, we can increase to 5 cycles per year. Ultimately, the production target is 450 tonnes/ha at a production cost of USD 2/kg for 20 g shrimp by lowering fixed costs. This is a threshold for a new era in shrimp farming.”

Published in July/August 2016 AQUA Culture Asia Pacific Magazine

Wednesday, February 15, 2017

Aquamimicry: A revolutionary concept for shrimp farming

The prevalence of numerous diseases that affect the shrimp and prawn aquaculture industry has promoted the development of various health management strategies. Some include greater biosecurity and sourcing of specific pathogen free animals, and in more extreme cases, using chemicals and antibiotics.

However, because of the nature of open pond aquaculture, where most farmed shrimp is produced globally, it is often not possible to farm animals in a bubble by completely eliminating the presence of all pathogens.

In fact, in traditional pond systems, the continual build-up of sediments and subsequent deterioration of water quality are known to encourage the growth of many pathogens including pathogenic Vibrios. Promoting microalgae growth can help maintain water quality, but this can sometimes be hard to manage, and these systems are prone to pH and dissolved oxygen fluctuations that can stress the animals.

Biofloc technology was introduced to tackle some of these issues. This is accomplished by the addition of extra carbon to the water, leading to the conversion of potentially harmful organic matter and sludge into consumable biomass. Such a process can eliminate or significantly reduce the need for water exchanges, and is thus more environmentally friendly while also offering greater biosecurity.

Biofloc technology has been met with success around the world; however, the operating costs can be significantly higher to maintain bioflocs in constant suspension. A potentially more balanced approach between using both microalgae and biofloc in aquaculture is known as Aquamimicry. In this article, I present a simple description of the protocol and implications for its use to assist farmers considering this concept, which I believe will become a widespread standard practice in the industry.

Aquamimicry simulates natural conditions
Aquamimicry is a concept that strives to simulate natural estuarine conditions by creating zooplankton blooms (mainly copepods) as supplemental nutrition to the cultured shrimp and beneficial bacteria to maintain water quality. This is done by fermenting a carbon source, such as rice or wheat bran, with probiotics (like Bacillus sp.) and releasing their nutrients. This method is in some ways similar to biofloc technology, but there are some key differences.

Firstly, the amount of added carbon is reduced and not strictly reliant on ratios to nitrogen input. Secondly, rather than encouraging and suspending high amounts of bioflocs, sediments are removed in more intensive systems to be reused by other animals.

Ideally, the water mimics the appearance and composition of natural estuarine water that includes microalgae and zooplankton. When such a balance is met, pH and dissolved oxygen fluctuations are minimized, and there is no need for antibiotics or chemicals because the rice bran provides nutrition for the zooplankton and bacteria (as a prebiotic) to create “synbiotics,” which are dietary supplements or ingredients that synergistically combine pre- and probiotics.

The success of this approach includes decreasing the feed conversion ratio, minimizing water exchanges and eliminating disease.

The initial idea towards the development of this protocol occurred in Thailand during the disease outbreaks in the 1990s. At that time, it was noticed that in some extensive shrimp ponds the shrimp were growing well and disease-free, despite being in close proximity to infected ponds. No formulated aquafeeds were used, as the farmers had limited resources. Instead, only rice bran was used and it was thought to be a potential reason for the better performance in extensive ponds. Over time, and after extensive trial and errors, a protocol slowly developed.

When this concept was first introduced outside Thailand, many farmers decided to first try this concept in their worst performing ponds. This was sometimes seen as a last chance attempt before switching to fish farming or getting out of the aquaculture industry altogether. However, within the first batch, pond production costs were reduced by half, and the practice significantly expanded to more ponds. Currently, some form of this concept is being adopted in various countries including Vietnam, China, India, Ecuador, Korea and Egypt. As with any farm, there are some variations to the protocol depending on available resources and the farmer’s experience.

The success of this approach includes decreasing the feed conversion ratio, minimizing water exchanges and eliminating disease. A variety of factors are believed to contribute, such as a better overall nutrition of the animal, reducing stress associated with fluctuating water quality, and minimizing environmental conditions favorable to pathogens.
General layout of a farm in Thailand where the Aquamimicry concept has been adopted for intensively culturing shrimp. (A) grow-out pond with eight long-arm paddlewheels (3-hp at 85 rpm) arranged to promote water circulation around the pond for solids to concentrate in the center; (B) sump (13-m diameter and 2-m deep) is lined; (C) sedimentation pond (4-m deep in the center) containing milkfish or catfish, and with water overflowing to (E), biofilter pond containing tilapia. Plastic lining is arranged to slow the water velocity and increase the water retention time. When the water returns to the growout pond, there very low levels of nitrogenous waste.

Pond preparation
Using a filter bag (200-300 μm), the pond is filled up to a depth of 80-100 cm, probiotics (Bacillus sp.) added, and the pond is chain-dragged for seven days. If lined ponds are used, heavy ropes should be used instead to prevent tearing the liner. Gentle dragging is done to enhance soil mixing with the probiotics and to minimize the development of biofilms that could potentially be toxic to the shrimp.

To eliminate any small fish or eggs, teaseed cake (at 20 ppm) is applied along with fermented rice bran or wheat bran (without the husk) at 50-100 ppm. More additions result in more copepod blooms, which should happen within two weeks. In the meantime, full aeration is necessary for proper mixing, to reduce teaseed cake levels, and to mix the nutrients and probiotics in the pond.

Carbon source preparation and use
A complex carbon source, such as rice or wheat bran (without husk), is mixed with water (1:5-10 ratio) and probiotics under aeration for 24 hours. If the bran is finely powdered, the entire mixture is added slowly to the pond. If crumbled, the upper “milk” or “juice” is added to the pond and the bran solids are fed to fish in the biofilter pond. The pH of the incubation water should be between 6-7 and adjusted if necessary.

Once the shrimp are stocked, which can be at densities of 30-100 animals/square meter, the amount of fermented bran to be added is dependent on both the system and the turbidity level. As a general guideline, 1 ppm is recommended for extensive systems, while for intensive systems, 2-4 ppm is used. The ideal turbidity (using a Secchi disk) should be around 30-40 cm. If higher, less bran should be added and vice versa.

During the growout period, additional probiotics should be added each month to help maintain water quality and to promote the formation of biocolloids (flocs composed of detritus, zooplankton, bacteria, etc.). Following 15 days after pond stocking with shrimp, slowly dragging chains or ropes on the pond bottom (but not over the central drain) is encouraged to minimize the formation of biofilms.

For extensive systems, there is generally no need for further water quality management or action. For intensive systems, however, there is a need to remove excessive sediments (e.g., through a central drain) to a sedimentation pond two hours after each feeding. Regardless of the system type, the pH is reportedly stable throughout.
Draining effluent from a central drain in the growout pond to a sedimentation pond two hours after feeding the shrimp.

Sedimentation and biofilter ponds
The sedimentation pond should be deeper (up to 4-m in the center and 2-m on the edges) than the growout pond to allow sediment accumulation. In it, bottom-dwelling fish species – such as catfish or milkfish, depending on the water salinity – should be stocked at low densities. Their feeding on and stirring up the detritus help clean the pond system, and the fish can provide food for farm workers.

The sediments from the growout pond encourages the production of worms and other benthic invertebrates that the fish can consume. Meanwhile, if ropes or lines are present, these are frequently and strongly colonized by horse mussels. Not only do these help by further filtering the pond water and removing suspended solids, but can later be crushed and fed to the shrimp during production.

After the sedimentation pond, the water overflows to another pond to increase the retention time and act as a biofilter. Fish like tilapia can be added at low densities. From here, water overflows back to the growout pond with little nitrogenous waste. Every three years, the sedimentation should be cleaned.

Currently the ratio of these ponds is 1:1 (treatment to growout ponds), which obviously requires relatively large areas of land in relation to production. However, trials are currently underway to substantially reduce this ratio by adjusting water flows, carbon inputs and different combinations of live organisms in the treatment ponds.

After harvest
After harvesting, the pond bottoms reportedly have no smell, black soil or accumulated sediments, and the pond is therefore often ready to be prepared for the next production cycle by the addition of fermented bran and probiotics, as mentioned earlier. Farmers have stated that the shrimp have a deeper red color when cooked, which could be from the consumption of additional pigments from the natural food produced in the pond.

Although there is no information available yet, the omega-3 fatty acid content of the shrimp would likely be enhanced and would provide additional health benefits. This is of particular relevance, as the aquaculture industry is increasingly relying on land-produced aquafeed ingredients that can lead to lower levels of omega-3 fatty acids in the final products.

Perspectives
Two major drawbacks to the Aquamimicry approach include the potential difficulty of applying this concept to indoor conditions, as well as the use of relatively large treatment ponds. Within indoor raceway systems in Korea, the adoption of this concept reportedly gave better results when compared to a biofloc-based system. However, it became necessary to discharge excessive sediments, which were not reused again.

To deal with the issue of large treatment ponds, currently there are efforts being made to reduce this ratio with the growout ponds, but on more extensive systems no treatment ponds are necessary. As with any new aquaculture technology, farmers interested in this new protocol should first perform trial runs to determine whether this can be successfully applied to their particular circumstances.

Because reportedly better-quality shrimp can be produced at lower cost and in a more sustainable manner, the concept of Aquamimicry is rapidly spreading throughout the world. Some interpretation of the concept will undoubtedly become a new standard in shrimp farming and benefit future generations in the industry.

Author’s note:
This short article is based on my recent attendance to an Aquamimicry workshop in Thailand, 9-13 January 2017. The event was organized by the Aquamimicry Aquaculture Alliance. The program managers were Veerasun Prayotamornkul, Jimmy Lim, Clen Cho and David Kawahigashi. For more technical details regarding the amounts and types of probiotics, please visit www.bioshrimp.com

By: Nicholas Romano, Ph.D.
Source: www.advocate.gaalliance.org