During the FAO Technical Conference on Aquaculture held in Kyoto, Japan, 26 May to 2 June 1976, the consultant presented a paper entitled “The brine shrimp, Artemia salina: a bottleneck in mariculture?” and convened a meeting of a working group (ANNEX B). The paper and working group report elicited much interest among delegates to that Conference. Subsequently, a side trip was arranged to enable the consultant to visit the SEAFDEC aquaculture complex in Iloilo, Philippines, during the period 10–16 June 1976. The object of this visit was to develop a programme in order to improve the use of Artemia in the SEAFDEC hatcheries.
Based on observations made during this first visit at SEAFDEC, the following recommendations were formulated:
Use another brand of cyst, cheaper and of higher quality.
Improve the hatching and separation techniques presently used in Tigbauan;
Consider the following studies to be undertaken:
Decapsulation of cysts (removal of the hard shell by exposure of the hydrated cysts to a hyphochlorite solution)
Indoor mass production of bigger larvae (prawn food) and adults (cyst production) in air-water lift operated raceways on inert food
Outdoor mass production of adults and cysts in ponds
It was furthermore postulated that three options can be considered in producing Artemia:
Production of nauplii (hatched out of the imported cysts), larvae and adults as a highly nutritious food for Penaeus monodon, Macrobrachium rosenbergii, Scylla serrata and Chanos chanos larvae;
Production of cysts which can be sold to the (national and/or international) aquaculture hatcheries and the petshop market (aquarium hobbyists);
Production of animal protein (Artemia is an herbivorous filter-feeder, with a minuscule exoskeleton, its meat containing 40–60% protein).
This visit to SEAFDEC was made during March and April 1977 for a period of six weeks. During this period, besides the services of the consultant, his assistant biologist, Eng. Etienne Bossuyt, was also utilized for a three-month period (March-June 1977). This was done in order to follow up more closely the various programmes initiated in this work.
The following programmes were undertaken:
I. Hatching of Artemia nauplii
Suggestion to use another brand of commercial cysts, based on the following findings:
Usually utilized in the SEAFDEC hatcheries previously was LONGLIFE-brand (Great Salt Lake, Utah, U.S.A.) Price: US$50 per kg
50-gram cyst was needed for the production of 1 million nauplii
long incubation time until hatching: 36 hours at 28°C
SAN FRANCISCO BAY-brand (Leslie Salt Ponds, San Francisco Bay, California, USA) was acquired upon suggestion for the following reasons:
Only 5.5 gram cyst was needed for the production of 1 million nauplii
Shorter incubation time until hatching: 24 hours at 28°C
Price: US$50 per kg
It is estimated that with this change, SEAFDEC can decrease its Artemia expenses by 88%.
Utilization of a new hatching container (50-liter plexiglass tank with funnel-shaped bottom).
Advantages as compared to the old method:
Cheaper construction
Volume of water 5 times smaller for the hatching of the same number of larvae (saving of energy for pumping, heating, manual labour, etc.)
Decapsulation of the cysts
Routine procedure for the daily decapsulation of the Artemia
cysts to be incubated for nauplii production (food for shrimp,
prawn and crab larvae)
Advantages:
No more separation of the nauplii from the hatching debris (important economy measure - minimum 10% saving of cysts, no more extra equipment nor manual labour needed)
Absolute elimination of contamination risks for the cultured species through the spores of plant and/or animal origin normally found on the cysts
Possible direct ingestion and digestion of the decapsulated cysts by the cultured species - no more hatching equipment nor manual labour needed in order to produce the nauplii; higher energy content of the decapsulated cysts as compared to the hatched nauplii
Suggestion to standardize the hatching procedure: constant temperature, light, salinity, timing for incubation and harvesting.
This is in order to assure to always harvest:
The maximum number of nauplii which can be obtained from the quantity of product incubated (can differ considerably, see Sorgeloos, Remiche-Van der Wielen and Persoone, 1978) - economy in the quantity of cysts needed
Instar I nauplii and not Instar II or III larvae which mostly occur when not working in standard conditions. This can result in an economy on the quantity of cysts needed by a factor 25%. Changes from Instar I to II - III results in loss of nutrient content as follows:
Ash-free dry weight - 26%
Individual caloric content - 27%
Fatty acids - 26% (for more details, see Benijts et al, 1976)
II. High density culturing of the larvae to the adult stage
Methodology and technology of air-water-lift operated raceway culturing of Artemia on inert foods
The use of dried algae (Spirulina imported from Mexico) instead of live algae makes the culture of Artemia already much easier and cheaper. However, further research on the suitability of locally available feed (fish meal, shrimp head meal, ricebran, etc.) might lead to a considerable economy of the price of indoor-produced Artemia.
This new technology in Artemia culturing might lead to the following applications:
Production of a bigger food, which furthermore is of a higher nutritional value than the freshly hatched nauplius - saving of about 90% on the quantity of Artemia cysts needed for feeding those larval stages of the cultured species which can be fed with a 2–3 mm Artemia larvae (dry weight increase from nauplii to 3 mm larvae - 15 times)
Production of adults - animal protein of very high quality (nearly no exoskeleton - no wasts; up to 60% protein)
Production of live nauplii (ovoviviparous reproduction) of direct use in the aquaculture hatcheries or of cysts (oviparous reproduction) which can be processed (and later decapsulated) and stored for later use in the hatcheries or for sale.
III. Outdoor production of Artemia in ponds
Information should be gathered with regard to site selection, physico-chemistry of suitable areas, selection of suitable strain, etc.
IV. During this visit some time was also spent with the phycology team and the following programmes were initiated:
Development of a new 250-liter culturing unit for the intensive indoor culturing (Sorgeloos, Persoone, De Winter et al, 1977).
Laminar flow circulation system for the 2-ton fiberglass tanks.
Suggestions were made for new equipment with regard to filtration, stock maintenance, chemical analyses, etc.
The consultant's third visit to SEAFDEC was during the period January to March 1978 for a duration of seven weeks.
I. Hatching of Artemia nauplii
Selection of commercial brand
SEAFDEC ordered 120 cans (150 kg) of cysts at HALEWYCK & CO. (Ostend, Belgium) in December 1977. The consultant was able to delay the order until the end of January 1978, which resulted in considerable saving. SEAFDEC should normally have received a particular batch of Australian Brand cysts (World Ocean) 10 g productineeded for the production of 1 million nauplii, whereas for the batch of San Francisco Bay Brand, which will be used now, only 4 g is needed to produce the same number of nauplii.
Further simplification of the hatchery procedure by the utilization of plastic bags. The desired size or volume can be fabricated with locally available plastic sheet and heat-sealing apparatus instead of constructing complex funnel-shaped hatching containers (Fig. 1).
Decapsulation of Artemia cysts
Since last year, the technique of decapsulation of Artemia cysts (Sorgeloos et al, 1977) has been improved as follows:
Economy in the quantity of hypochlorite needed: 1 liter (versus 1.7 liters actually used) of 5.25% technical NaOCl solution for the treatment of 100 g cysts (Bruggeman et al, 1978).
Simple and accurate method for checking the activity of the technical hypochlorite by measurement of the “Refractive Index” utilizing the American Optical refractometer used in the SEAFDEC hatcheries for salinity checks (Bruggeman et al., 1978).
Possibility of purifying the decapsulated cysts from heavy and light debris (sand, plumes, empty membranes, etc.) by differential floatation (Sorgeloos, 1978).
Possibility of storing the decapsulated cysts in brine at room temperature without affecting their viability: dehydration in a saturated solution of technical sea salt to which per 100 g cysts 10 ml of a 0.5% technical sodium thiosulphate solution has been added.
Proposal for the routine cysts-nauplii operations at the Tigbauan Center.
Flow chart procedure for the large-scale decapsulation of cysts
| x kg of cysts ↓ | (Quantity needed for 1 hatchery operation or quantity of cysts consumed over a period of several weeks) |
| Decapsulation, desactivation, dehydration, elimination of debris ↓ | |
| Quality analysis ↓ | (x cysts for 1 million nauplii) |
| Distribution in different quantities ↓ | (for example, daily ration for 200-ton tanks, small-scale hatchery, crab hatchery, etc.) |
| Storage at room temperature in brine |
Advantages:
Centralized operations resulting in economy of time, manual labour and equipment.
Guaranteed hatching success by avoiding the present problems with cans which remain open for days to weeks and from which the hatching success decrease.
Precise production of the number of nauplii needed (no more wastes due to over-production)
Centralized hatching in a temperature controlled (28°C) room resulting in optimization and economy of the use of cysts and nauplii. This was previously recommended in 1977 and is expected to be implemented in 1978.
Meeting with the project leaders using Artemia in their programme in order to determine the daily quantities needed; the periodicity over the year and to discuss the proposals 1 and 2.
Application of the standard method for the hatching evaluation of Artemia cysts as developed at the Artemia Reference Centre in Belgium (Sorgeloos et al., 1978).
Feeding tests with non-hatched decapsulated cysts for Penaeus and Scyllalarvae. These experiments were conducted in collaboration with A. Laviña and C. Mock. The use of decapsulated cysts instead of freshly hatched nauplii as a food for crustacean and fish species would contribute to a further economy in the use of Artemia in the hatcheries.
Higher energy content of decapsulated cysts (24 hours metabolism until hatching) saving of the quantity of cysts needed per unit dry weight or calories (data to be gathered).
No more labour or equipment needed for hatching.
No more risks for food competition between the Artemia nauplius (also filter-feeder) and the cultured species.
II. Indoor culture of larvae and adults
Construction of rectangular air-water-lift operated raceways (Fig. 2). Much cheaper and easier to operate than the 2.5 m3 conical tanks presently in use.
Working out a routine culture technique
Preparation of food
Ricebran has been found to be a suitable artificial feed for Artemia. In the Philippines, ricebran costs less than one peso per kilo (versus US$5/kg, transport not included, for Spirulina which is imported from Mexico). Ricebran is available locally. The particle sizes of this from of ricebran include sizes below 60 microns which are suitable as Artemia feed and sizes above 60 microns which are acceptable for Artemia. For this reason, the local ricebran is homogenized in a kitchen blender and passed through a 60 micron nylon screen. The suspension prepared contains approximately 100 g of ricebran per liter. The resulting suspension is either salted for a week's use or kept in the refrigerator without salt for a couple of days storage. Presently efforts are being made to locate a mill which can grind ricebran in large quantities locally. Such a mill is used in Belgium to grind ricebran to a particle size smaller than 60 microns.
Distribution of ricebran to Artemia cultures
The ricebran feed suspension may be distributed manually in the Artemia cultures and the resulting turbidity measured manually by a modified Secchi disc (Fig. 3). Several distributions affected are made each day and a turbidity range of 10 to 20 cm is maintained.
For automatic distribution of food, the systems illustrated in Figs. 4 and 5 allow a wide range of feed distribution programming. Presently in use is a 1/5 rph motor with a cam allowing a food distribution every 30 minutes, adjustable between 0 to 60 seconds or 0 to 5 minutes duration.
Results of a comparative run using a 1 m3 fiberglass raceway and a 2.5 m3 conical tank.
| Size of tank (m3) | Initial stocking density (No./1) | Amount of ricebran fed in 7 days kg) | Estimated % survival after 7 days | Mean total length of animals after 7 days (mm) | Total wet-weight of animals after 7 days (kg) |
| 1.5 | 1500 | 2.07 | 39 | 4.39 | 1.71 |
| 2.5 | 1000 | 4.07 | 73 | 4.71 | 3.16 |
Recommendations
Studies should be undertaken to test the suitability of other locally available feeds such as ipil-ipil (Leucaena sp.), rice hull, sugarcane molasses, copra meal, etc.) In the laboratory, tests can be done in inclined 1-liter bottles. Using a cam-timer and magnetic valves (Fig. 5), a 10-second aeration is given every 30 minutes. Food is distributed 2 times a day. At the end of the experiment, the following criteria are considered: survival, growth rate, time to riding (copulation), length of first-riding couples.
Biochemical analyses of pre-adult Artemia fed with different diets including ricebran (through Ghent laboratory).
The nutritional value of ricebran might vary depending on the storage conditions. This hypothesis should be tested.
Nutritional tests with different predators (shrimp, fish, crab); parameters to be studied:
size of the Artemia larvae as function of the size and stage of the cultured species
food source (ricebran, shrimp head meal, fish meal, etc.) - difference in nutritional value
empty or full digestive tract - fouling of the culture medium
live or frozen - food competition with the cultured species; risk for contamination via the live Artemia
dried Artemia might be mixed as an ingredient of pellets
For cost analysis, food conversion studies may be done in raceways.
Indoor production of cysts - automatic removal of the faeces and harvesting of the cysts.
Techniques used:
A density of 200 adult individuals per liter can be maintained in the raceway with minimum mortality (salinity 70–90 ppt)
Food: ricebran mixed with chlorophyll containing food (Spirulina or a substitute) manual distribution in the day and automatic distribution during the night and/or day
Addition of FeEDTA1 to give a final concentration of 1 ppm Fe in the culture medium
Faeces/cysts harvesting apparatus (Fig. 6)
Advantages
Better water quality control, which may allow the rearing of higher densities.
Important reduction of the manual labour involved.
Collected faeces might be dried and used as a fertilizer or be recycled in a feed-back culturing system.
1 EDTA is ethylenediaminetetraacetic acid, a chelating agent
Procedure applied
Putting off the aeration for 1 hour in the morning to reduce oxygen in the water thereby stressing the animals (believed to induce cyst production). The live adults stay at the bottom of the tank while the dead and weak ones float at the surface. (The live adults soon swim near the surface as 02 becomes depleted in the water).
Collection of the cysts and the adults floating at the surface of the tank with the use of a double screened dip net (Fig. 7). When the live adults start swimming near the surface, the collection of dead adults and cysts is stopped.
Production results: 54.5 g of cysts were harvested during 10 days from February 28 to March 9 (raceway volume - 1 m3)
Studies to be undertaken for optimization of the technology for indoor cyst production:
Perform initial tests with low densities (100–200 individuals per liter). Once a routine procedure is standardized, study the possibility of working at higher densities.
Study the influence of food quality and quantity and the turbidity of the culture medium on the quality and quantity of reproduction.
Possibility of using cheaper Fe2+ sources than FeEDTA (presently used) for the induction of the oviparous reproduction.
Routine procedure for the determination of the qualitative (nauplii versus cysts) and quantitative production
Quality analysis of the produced cysts: hatching rate and efficiency, size of cysts, thickness of chorion, nutritional value of decapsulated cysts of nauplii. etc.
Selection of the most suitable strain for cysts production (parthenogenetic).
Optimization of the faeces/cyst harvester: study of retention times; ratio volume tank/volume sedimentation system.
Study of the economics of indoor Artemia cyst production (at present demonstrated to be economically feasible when at a price of US$ 50 to 60 per kg).
III. Outdoor production of Artemia (adults and cysts) in salt ponds Provided:
Suitable climatic conditions (temperature 25–30 °C; high evaporation rates; high water salinity 80–200 ppt which serves as ecological barrier).
Salt ponds the intake water of which is from a mangrove area (known as the ecosystem with the highest productivity; mainly suspended particles).
Inoculation of the salt ponds with acclimated Artemia populations should be considered and might lead to an important production of cysts and animal protein (adults)
Example: Macau (Rio Grande do Norte, Brazil)
April 1977: inoculation in a 10-ha pond (100 ppt salinity) with acclimated nauplii (San Francisco Bay strain) hatched out of 250 g cysts.
June 1977: harvest of the first kilograms of cysts, the Artemia population was spreading out over the entire salt pond system (several 1000 ha).
December 1977: by that time over 3000 kg of good quality cysts had been harvested.
Proposal
Select suitable areas in the Philippines
Inoculation tests in 1978
Evaluation of the production results obtained by the end of the dry season
Prepare routine large-scale procedure for the new inoculation and harvesting for the dry season 1978–1979.
Since the salinity of the ponds at the SEAFDEC-Leganes station, designed for Artemia production, was only 40 ppt, the inoculation with Artemia could not be considered. However, arrangements were made between Mr. Ceferino de los Santos, private salt pond owner and SEAFDEC to set up a joint Artemia production test in a few salt ponds in Barotac Nuevo, Iloilo.
On February 22, 1978, about 125 000 pre-adult Artemia and 20 million nauplii (both San Francisco Bay Brand strain) were transported from Tigbauan, Iloilo to Barotac Nuevo, Iloilo and inoculated in a 300 m2 concrete tank containing 90 ppt brine (depth: 50–70 cm).
Transport conditions
The 125 000 pre-adults and twice 10 million nauplii were placed each in a plastic bag to which 20-liter brine (70 ppt); 0°C) was added.
The plastic bags were kept cool in individual styrofoam boxes containing ice.
Aeration from portable aerators were provided to the nauplii bags. Upon arrival at the farm (3 hours drive) the survival approximated 50% for the pre-adults and about 100% for the nauplii.
Observations on March 4, 1978:
Since the time of inoculation, about 5 kg of ricebran sieved thorugh a 60 mm screen had been added to the concrete brine tank. The preadults previously inoculated were reproducing while the inoculated nauplii had developed into pre-adults and were seen crowding in several parts of the tank. The salinity of the brine tank was 110 ppt and the temperature 31°C. A portion of the population had been inoculated in pond 4 (area - 2 819 m2) and pond 5 (area - 3 557 m2) whose salinity was 140 ppt and temperature measured 34°C. The brine shrimp were found mostly in shaded areas.
The following suggestions were given:
Add creek-water at weekly intervals in order to maintain the salinity of the pond within the 100–150 ppt range. In this way, the fresh food will be added and since at lower salinities ovoviviparous reproduction usually occurs, the population will increase exponentially.
Once the population density is estimated high (100 and more adults per liter) let the salinity increase in order to stimulate cyst production.
Install a bamboo or plastic screen in these corners of the pond where the cysts are accumulated by the wind.
Stirr up part of the benthos at regular time intervals in order to resuspend the food.
Daily monitor the temperature and salinity.
IV. During the same stay, the following materials were supplied:
Chlorella species (marine) with following features:
Isolated by Dr. Dupuis (Chesapeake Bay, U.S.A.)
Can be digested by other invertebrates than Brachionus (which is not the case for the Japanese Chlorella)
Tests to be considered with Artemia and with other herbivorous larvae
STX 114 (Bellerochea species)
TISO (Isochrysis species)
Isolated by Dr. A. Haines fron an algal culture from AQUACOP, Tahiti
Tropical unicellular marine flagellate
During his one-week visit in November 1978, the consultant submitted the following proposals for the Artemia programme at the Tigbauan Center:
The feasibility of Artemia cyst production in the Philippines during the dry season has been demonstrated in a joint venture CEROMAR (Atty. C. de los Santos), SEAFDEC (Mr. E. Laviña and Mr. A. Bernardino) and the Artemia Reference Center (ARC) - State University of Ghent, Belgium (Dr. P. Sorgeloos): 25 kg good quality cysts were produced in the period March-May 1978 on a two-hectare area starting from 110 gram San Francisco Bay cysts (de los Santos, Sorgeloos, Laviña and Bernardino, Successful Inoculation of Artemia and Production of Cysts in Man-made Salterns in the Philippines - paper presented at the International Symposium on the Brine Shrimp, Artemia salina, Corpus Christi, Texas, U.S.A., August 20–23, 1979).
This is a major breakthrough for Southeast Asia, in fact one of the very few areas in the world where natural Artemia populations do not occur.
Man-managed production of Artemia in Southeast Asia for cyst and animal protein exploitation might lead to a considerable economisation, optimisation and consequent expansion of the hatchery activities in this part of the world.
In order to enhance the independence on Artemia cyst on import and to make Artemia cysts a cheap product in the Philippines, initiate a survey study for the whole area of the Philippines and stimulate the private sector (salt farmers, e.g. Dr. A. Araneta, Dr. S. Abesamis, Atty. J. Garay, etc.) to initiate Artemia production tests under the supervision of trained SEAFDEC personnel).
Start also a specific SEAFDEC project at the Leganes station in order to test the integrated production of Artemia, salt and milkfish (see layout of plans and operation as worked out by Mr. A. Bernardino: “Proposed 1/2 hectare saltbeds (24 tanks) and Artemia ponds (5) to be constructed in Leganes Fishpond System” (pilot demonstration scale).
The use of Artemia cysts at the SEAFDEC-Tigbauan Center for the respective fish and crustacean hatcheries can be optimized and economized by centralizing their Artemia operations (decapsulation, storage, hatching and distribution (see previous SEAFDEC consultancy reports).
Highly recommend to implement a central unit for Artemia operations from where the various shrimp, crab, prawn and milkfish teams can obtain the Artemia products they need.
Suggest to test the usefulness of decapsulated cysts as an inert diet for milkfish, shrimp, crab and prawn larvae.
The feasibility of producing an Artemia product larger than the freshly hatched nauplius and of a higher nutritional value (protein content up to 60% of its dry weight) on a cheap product, i.e. ricebran, has been demonstrated (see previous SEAFDEC consultancy reports, Sorgeloos, Baeza-Mesa, Bossuyt, Bruggeman, Dobbeleir, Versichele, Laviña, Bernardino, Mock and Talloen- “The culture of Artemia salina on ricebran - the conversion of a waste product into highly nutritive animal protein” - paper to be presented at the 10th Annual Meeting of the World Mariculture Society, Honolulu, Hawaii, U.S.A., 20–26 January 1979). Feeding experiments reported in literature (Aquacop-Tahiti; CNEXO-COB France; MAFF-United Kingdom, etc.) indicate that the use of bigger Artemia larvae as a food source results in an economisation and optimisation of the hatchery activities. In most nutrition experiments with fish and crustacean postlarvae, adult Artemia harvested from the wild are used as the best reference diet.
Suggest to set up feeding experiments with different Artemia sizes and preparations (live versus frozen versus dried; Artemia with full or empty digestive tract, etc.) for the various cultured organisms, i.e. milkfish, shrimp, crab and prawn.
Suggest to test ricebran cultured adult Artemia as a possible source of animal protein for man and/or various cultured organisms (e.g. ingredients of pelletized diets).
The feasibility of controlled intensive flow-through culturing of Artemia for the production of Artemia offspring has been demonstrated and might eventually be an alternative for fish or shrimp farmers to economize on Artemia cyst-cost.
Suggest to further explore and test this type of backyard Artemia production for application in the Philippines.
On the occasion of his short visit at the Shrimp Culture Research Centre in Jepara, the consultant formulated the following recommendations:
To look for cheaper sources of Artemia cysts - eventually use the Chinese brand of cyst but allow a longer incubation time for hatching;
To apply the Artemia cyst decapsulation procedure in the shrimp and prawn hatcheries;
To optimize the present Artemia hatching operations;
To test various inert foods which are locally available as possible food source for Artemia rearing (laboratory experiments);
To set up raceway culturing methods for the mass production of Artemia larvae and adults as a food source for the Penaeus and Macrobrachium hatchery - important saving on the quantity of cysts needed for the hatchery operations;
To survey the local salt pond areas and set up Artemia inoculation tests during the dry season in selected areas.
The various people met in the different aquaculture hatcheries visited are very enthusiastic and are working hard with the aim to improve their production results. They are supported by a very dynamic staff at the Department of Fisheries, Bangkok, who are eager to improve the present situation of the hatchery-aquaculture in Thailand.
There seems, however, a general lack or inadequacy of information on the latest developments in the world-aquaculture which, in my opinion, is the reason for the rather fair hatchery operations and the consequently relatively low production results. Although it is generally accepted now that in the hatchery stage (culturing period from newborn larva until the postlarva or fingerling stage) the highest production results, as well for fish as for crustacean species, can be guaranteed by intensive culturing operations (which allow a high degree of control on the critical culturing parameters). The following conditions apparently confirm the above observations:
Large tanks (sometimes hundreds of tons capacity);
Poor circulation patterns resulting in high sedimentation causing anaerobic conditions on the bottom of the tank;
A lot of work is needed for the daily cleaning of the bottom of the tanks;
Low density of the larvae cultured;
Short feeding period with Artemia resulting from high price of this commodity followed by feeding with mussel or shrimp meat which pollutes the culturing medium;
Very low survival rate from larva to postlarva or fingerling stage;
Very poor water filtration systems;
Foreign method introduced earlier of (non-controlled) algal food production resulting in blooming of the algae (after fertilization) within the culturing tank.
There appears to be only one source for the Artemia food, i.e. very expensive imported Artemia cysts. There is uncontrolled availability of the cysts and no control neither on the origin of the cysts in quality nor on the quantity. There is no control on the hatching systems as shown by the appearance of mixed and non-constant harvests of different instar stages. The separation of the nauplii from the hatching debris appears to be only partial. The Artemia food fed to the different cultured organisms consists of nauplii only.
Smaller tank, with better circulation of the medium, such as the Galveston type air-water lift raceway is suggested. The Galveston-technique should be tried and the production results compared alternately with the present method. Modify and/or adapt the existing techniques in order to develop a specific Thai-method of hatchery operation.
Better water filtration methods such as GAF-bag filtration or GELMAN-cartridge filtration technique.
Use low pressure cyclo-blowers for aeration purposes. This results in cheaper cost as well as lower energy consumption and there will be no more problems with oil contamination of the air.
Algal food production in separate tanks to produce batch cultures of a high density. The produced algal product can eventually be harvested and concentrated with a cream separator, and be stored in the deep freezer for later use. These new methods of food production and distribution can be tested alternately and the production results can then be compared with the present figures. The existing techniques may be modified or adapted in order to develop a specific Thai-method based on local experience.
For some cultured species (shrimp and fish) a rotifer diet (Brachionus plicatilis) should be tested as an intermediate food source between algae and Artemia. Brachionus can easily be grown on marine Chlorella which is very simple to culture in large volume.
(i) Import of Artemia cysts
A list of dealers of Artemia cysts are given in ANNEX E. It is strongly suggested, if possible, cysts should be purchased directly from producers, not via dealers in Bangkok for all the governmental hatcheries selecting the best quality and at the most reasonable price. In view of the increasing availability of Artemia cysts, the price on the world market is dropping. Recently, good quality cysts, i.e. 5-gram product for 1 million nauplii, have been sold at US$32 per kg.
(ii) Production of Artemia cysts in nature
Successful inoculation tests in Brazil and in the Philippines have indicated that, provided suitable climatic conditions is present, highly productive water supply and proper pond management, large quantities of Artemia cysts can be produced for the local aquaculture hatcheries. The initial results obtained are as follows:
| Brazil - | inoculation of 250 g cysts in July 1977 (area - 6000 ha) |
| harvest by May 1978 - over 10 000 kg | |
| Philippines - | inoculation of 50 g nauplii in February 1978 (area - 2 ha) |
| harvest by May 1978 – 25 kg |
In the Southeast Asia area, Artemia production in outdoor ponds will only be feasible in the dry season. The ecological barrier for production is the need to maintain salinities of 70 ppt and higher. As a consequence, a new inoculation will be needed at the start of a new dry season.
In Thailand, inoculation tests should be considered during the next dry season at the Samut Sakhorn and eventually at the Songkhla stations.
Since the water temperatures in the Thai-salterns rise over 35°C (very shallow ponds), a temperature which is critical for the San Francisco Bay strain which will be used for the first inoculation, deeper ponds should be constructed for the Artemia production. The outline of pond management and the practical operation are described in Section 2.3.5.
In the first year, different pond management systems should be tested (i.e. different salinity-regimes, water depths, pumping methods, etc.) in order to allow selection of the most appropriate technique for later application. In the future, inoculation tests with different strains should be considered in order to select a suitable strain for the Thailand climate. This might eventually allow the inoculation of Artemia in the existing salterns (high temperature resistant strain) leading to a combined salt and Artemia production (which is the case in many areas where Artemia naturally occurs).
(iii) Centralization and standardization of the hatching operations
A flow chart procedure for the decapsulation of cysts is given in ANNEX D. The application of this method has the following advantages:
No more separation of the nauplii from the empty and nonhatched cysts;
Disinfection of the Artemia cysts, thus solving contamination problems, for example with Anthozoa and Ciliata; and
Possible use of the decapsulated cysts (embryos) as a direct food for the cultured species. Detailed studies should be considered with the species in culture to test this latter application.
A standard procedure for testing the hatching quality of the cysts purchased is given in Sorgeloos et al. (1978) and in ANNEX D.
The hatching of the decapsulated cysts should be done under standard conditions (temperature, salinity, incubation time) in order to always harvest the maximum number of instar I nauplii.
Test HE and HR of cysts decapsulated following Thai-adapted decapsulation method with Ca-hypochlorite and Ca-oxide (compare with original ARC-method)
Develop routine procedure for the weekly decapsulation of cysts (followed by storage until incubation for hatching)
small-scale tests for viability control upon storage (HR and HE)
Construction of simple brinomat (automatic production of 300 ppt technical grade NaCl-solution)
(ii) The feeding of pre-adult Artemia (cultured or ricebran) to Macrobrachium larvae
important saving of cysts
better food than freshly hatched nauplii (bigger and of a higher nutritional value: 60% versus 40% protein content)
feeding tests with different Artemia sizes (test Artemia with full or empty digestive tract; express size of Artemia as 3 to 7 days old larvae) for different Macrobrachium sizes.
eventually try various dip-methods (in formaldehyde solution, brine, etc.) to prevent contamination of the Macrobrachium culture-medium via the Artemia feeding procedure
if good results are obtained set up a pilot scale application for the daily production of x million Artemia larvae of y days old (see results obtained above).
The feasibility of such an intensive Artemia production has been demonstrated at the Chachoengsao Center, October 29, 1978 harvest of 875 g adult Artemia (Chaplin Lake strain) from a 500-liter raceway with automatic ricebran feeding.
(iii) Backyard production of Artemia nauplii
Principle - batch culturing to adult size with ricebran
- flow-through culturing of adults with continuous
automatic harvest of nauplii (eventually cysts)
and faeces (Fig. 8)
Test 2 alternatives
(a) Open system
continuous inflow of fresh seawater (good quality, 30 ppt salinity; retention time of maximum 3 hours)
semi-continuous automatic distribution of ricebran- suspension
(iv) High density culturing of Artemia larvae on ricebran in airwater-lift operated raceways (Bossuyt and Sorgeloos, in preparation).
Batch culture: production of bigger larvae and/or adults as a food source for the various cultured species. This results in:
higher nutritional larvae than instar I nauplii, e.g. 60% protein versus 40% protein content in nauplii;
important saving on the quantity of cysts needed;
after drying or freezing, the adults can be used as a diet- ingredient for the older age stages of the cultured species.
Flow-through culture: continuous production of instar I nauplii which automatically can be harvested (methodology see Tobias et al., in preparation). The nauplii can either be fed directly to the predator or be cultured to a larger size in a batch culture AWL-raceway (see above). Production estimates: over 10 million nauplii per day for a 1 m3 system.
(v) In order to have a better collaboration and exchange of information for workers involved in Artemia work at the national level, meetings and working sessions in Bangkok for the various aquaculture centres involved from Songkhla, Phuket, Chachoengsao, Rayong and Samut Sakhorn should be arranged at a future date.
(FAC Associate Expert, THA/75/008) and Mr. Anand Tunsutapanich (Thailand Department of Fisheries) at the Chachoengsao Macrobrachium Research Center
(i) Optimization of the decapsulation and hatching procedures:
Test hatching rate (HR) and hatching efficiency (HE) of purchased cyst-batches (before and after decapsulation, low salinity, high pH)
Select strain for bulk-purchases
Compare the Artemia Reference Center (ARC), State University Ghent, Belgium) method for hatching decapsulated cysts (high densities; suspended self-made funnel-shaped plastic bags) with the Hawaii method (low densities; 80 1 buckets) presently in use in Chachoengsao
To be considered later: continuous inflow of filtered (100–200–300 mikron) mangrove swamp water.
(b) Semi-closed system
Tilapia fed chicken food in storage tank containing high salinity water - production of green water (digestible for Artemia) which will be circulated through the Artemia tank.
Green water at 15–20 ppt is non-digestible for Artemia (Chlorella saccarophila?)
To be experimented in 250 liter culture tests: gradually increase the salinity (Tilapia can survive up to 100 ppt) Chlorococcales do not resist high salinity; one could expect blooming of other algae (i.e. flagellates) which now might be digestible; run weekly growth tests with Artemia in green water of various salinities (glas bol tests)
upon finding suitable conditions run small-scale test with adult Artemia: 500 l tank for Tilapia; 10 l aquarium for Artemia
(iv) Inoculation tests of Artemia in existing and new salt ponds- production of cysts and adults (should be started in December 1978 at the beginning of the dry season)
Select small ponds in various existing salt farms for Artemia culturing tests (Chachoengsao, Chonburi, etc.)
Construct Artemia production ponds at Samut Sakhorn station (layout of ponds, dikes and canals in Fig. 9)
Prepare ponds for Artemia inoculation
Inoculation procedure
conditions: brine at 100–120 ppt free from predators (small fish Tilapia, goby and mullet; insects Corixidae); maximum temperatures not above 34–35°C.
production of instar I nauplii (San Francisco Bay strain- SFBB - 2596 obtained from ARC) from decapsulated cysts (3–5 million per hectare) in 10–20 liter plastic bags in natural seawater
transfer to salt pond (in the evening); eventually chill the Artemia suspension (addition of ice cubes) for transport (aerate or intermittently mix the nauplii suspension)
Operations:
Maintain salinity in 2 ponds within 100–150 ppt range Let salinity increase to higher ranges in 2 other ponds
| Daily | • monitoring | - temperature (air and water) |
| - salinity | ||
| - eventually pH | ||
| - eventually DO |
• harvest of cysts to be stored in saturated brine until processing
Weekly • estimation of population density and composition by core-subsampling method
salinity adjustment by mangrove-water intake (eventually partial draining + recuperation of adults)
sample at random 15 couples from each pond; incubate in laboratory in separate beakers containing respective pond water, for 4–5 days; check mode of reproduction (cysts versus nauplii) and eventually the number of offspring produced
processing of harvested cysts (Sorgeloos, 1978)
cleaning: bi-phase floatation method decapsulation - dehydration - packaging or drying-packaging-vacuum and/or N2 sealing
• Quality analysis of the cysts produced:
In the near future, the aquaculture activities in Thailand can make an important progress by adapting new culturing technologies for the hatchery and specially by working out a detailed Artemia programme for the production of cysts in salt ponds and the optimization of the use of this food source for the various cultured species. This might not only make Thailand (nearly) independent of Artemia cyst import (important for the economy) but once this food organism is available “ad libitum” better production and survival results for the various cultured species can be expected. Especially with regard to Macrobrachium production, where the main bottleneck is Artemia food provision, this achievement might make Thailand a leading country in this field of aquaculture.
