THA:75:008/78/WP/2 PLAN FOR THE DEVELOPMENT OF PRAWN FARMING IN THAILAND AND RECOMMENDATIONS TO INCREASE PRODUCTION OF JUVENILES FOR DISTRIBUTION TO FARMERS AND FOR STOCKING NATURAL AREAS

by

Takuji Fujimura¹
Consultant
National Freshwater Prawn Research and Training Centre
Freshwater Fisheries Division, Department of Fisheries
Ministry of Agriculture and Cooperatives
(FAO/UNDP/THA/75/008)

Bangpakong, Chachoengsao
Thailand
1978

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1. INTRODUCTION

The following is a plan of execution to develop freshwater prawn farming as a commercially viable new industry in Thailand. This plan of execution complies with the FAO/SCSP project, THA/75/008 Programme for the Expansion of Freshwater Prawn Production.

Some phases of this plan are similar to the plan that was enjoyed by the Anuenue fisheries Research Center in developing prawn farming in Hawaii over the past seven years. However, the similarity is only in the areas of activity that have universal applicability.

Research projects, modifications of existing facilities and capital improvement that are required to solve problems at the Bangpakong and Songkhla stations are specific.

These problems must be solved at both stations in order to attain the objectives listed below.

¹ Present position and address: Chief, Anuenue Fisheries Research Center, Division of Fish and Game, 1151 Punchbowl Street, Honolulu, Hawaii 96813 U.S.A.

2. OBJECTIVES

1. Provide extension service, consulting service, training, and act as an information center to public and private sectors interested in prawn farming.

2. Produce and provide prawns (juvenile and breeders) to the public and private sectors engaged in activities relating to prawn farming.

3. Conduct research to develop new and useful hatchery and pond management techniques and improve existing rearing techniques for higher production or lower operating cost.

4. Stock reservoirs and natural waters with juveniles to create prawn populations or to supplement existing populations for public consumption and evaluate the socio-economic impact of this project objective in the rural areas.

3. PLAN COMPONENTS

3.1 Advisory services

The extension programme, consulting and information dissemination services falls within the category of advisory services. This service has been on-going for several years in Thailand.

The following outline identifies the procedure and activities to be taken for now and the future. Immediate response to current and future needs expressed by the programme participants, such as private farmers and public agencies is envisioned under this plan of execution. This service is expected to facilitate expansion of the prawn farming industry by minimizing errors and consequently, failures.

As required, each prospective farmer is carefully guided through all of the necessary developmental steps, cautioned on all known pitfalls and provided with first hand instructions on farm management techniques. Existing farmers will be informed of newly developed technology.

The following procedure will be used:

1. Site selection

   1. Conduct chemical analysis of soil and water, including permeability of soil and reliability of water sources and volumes

   2. Study the topography of the site and layout ponds on plot plan or at the farm site utilizing contour maps or a transit for least cost in construction and operation

2. Designing and constructing a farm system

   1. Provide plans (blueprints and sketches) and specifications for ponds, water intake and discharge systems, roadways, supporting facilities, etc.

   2. Inspect construction for compliance with plans and specifications

   3. Recommend ground cover (grass and plants) for stabilization of pond banks and roadways, habitat for prawn and forage organisms and types of fertilizer according to soil analysis

   4. Start plankton blooms in ponds and instruct on methods to control blooms

3. Stocking of ponds and management techniques

   1. Provide juvenile prawns free for the first three years and at cost thereafter

   2. Provide feeding schedule and instruct on methods to determine over or under feeding

   3. Demonstrate and instruct on harvesting method and rate

   4. Demonstrate and instruct on sampling method and interpretation of data to determine standing crop, growth rate and expected production

   5. Instruct on methods to control water quality by interpreting interaction between weather, phytoplankton density by means of colour and secchi disc, feeding rate, standing crop, and water flow

4. Marketing

   1. Instruct on methods to blanch and ice prawns, and in transporting live prawns

   2. Assist farmers in freezing, sorting and packing prawns

5. Others

   1. Provide “trouble shooting” service, such as stopping mortalities or increasing production to expected levels

   2. Assist small farmers in organizing a prawn farmers' cooperative

3.2 Information dissemination

The staff of the Bangpakong Station will respond to all request for information relating to prawn farming. The degree of response will depend on the needs of the party making the enquiry. Research agencies that are interested in prawn farming will be put on the mailing list and new information developed by Bangpakong will be routinely mailed to them. They will also be notified of new technologies that are developed by others and copies will be mailed to them if requested. Farmers in Thailand will be routinely given the same information through the extension programme.

3.3 Technical training

The training programme will consist of both lectures and on-the-job training and it will be open to the general public. Training will be conducted at Bangpakong, government pilot farms, and private commercial farms by professional staff of the Inland Fisheries Division of the Fisheries Department. Lectures from various universities in Thailand will be called upon from time to time to discuss or lecture on topics in their field of specialty.

Topics that will be covered in the training programme are as follows:

1. Selection of sites

   1. wells (salt and fresh)
   2. hatcheries

   3. ponds

2. Design, construction, maintenance, operation of a hatchery and pond system including selection of materials, supplies and equipment

3. Rearing of larval and juvenile prawns

   1. selection of berried females
   2. incubation and hatching of eggs
   3. culture of plankton
   4. preparation of food and feeding rates

   5. transport of juveniles to rearing ponds

4. Rearing of market size prawns

   1. stocking rate
   2. formulation of artificial food and feeding rates
   3. culture of natural plant and animal forage
   4. harvesting methods and rates
   5. control of predators
   6. control of water quality

   7. collection, compilation and interpretation of pertinent data

5. Marketing

   1. transport of live prawns

   2. display of live prawns in the market

3.4 Production and distribution of juvenile prawns

The technology for the production of juvenile prawns has been worked out by researchers in Thailand and Hawaii and the basic rearing technique is, in general, similar. Changes have been incorporated to the basic rearing techniques to cope with conditions that are unique to the respective countries.

The Bangpakong and Songkhla hatcheries have been producing juvenile prawns and distributing them to private farmers and stocking many of them in lakes and natural waters for many years. This clearly exemplifies the capabilities of the staff assigned to the programme and the reliability of the basic rearing technology utilized in Thailand. Therefore, the following discussion addresses conditions, limitations, and problems that are unique to the Bangpakong and Songkhla hatcheries, and presents a plan of execution to cope with them so that production quotas can be met.

The production quota of juvenile prawns recommended for the Bangpakong Hatchery is 20 000 000 annually. This amount of juvenile prawns is required to carry out a meaningful development programme.

At a stocking density of 10 juvenile prawns per square meter, 200 hectares can be stocked annually with 20 000 000 juvenile prawns. Allowing an annual mortality rate of 50%, 10 000 000 can be grown to a size of 60 grams each or larger. Thus, the farmers can realize a total harvest of about 600 000 kilos annually. At a price of 100 baht per kilo the total gross income to the farmers will be 60 million baht annually. Even at a conservative production rate of 2 000 kilos per hectare annually, farmers can realize a gross income of 40 000 000 baht from a total of 200 hectares. In view of the fact that farming of freshwater prawns is proven to be profitable in Hawaii and can be made more profitable in Thailand because of the lower cost of land and labour, the opportunity to prove this point with noticeable impact from 200 hectares should be seriously pursued by every affordable means.

The Bangpakong hatchery complex consists of forty (10.5 ton) larval rearing tanks, sixty (45 ton) water mixing/phytoplankton culturing tanks and fifty-four (160 ton) research tanks.

Based on a production of 80 000 PLs (post-larvae) per tank per rearing cycle (a conservative estimate according to past records) all forty larval rearing tanks must be operated for 6.25 cycles to produce 20 000 000 PLs annually.

Water requirements to operate the 40 larval rearing tanks is 210 tons daily. This amount is required to flush 50% of the volume of water in each of the forty larval rearing tanks. The only source of water that can possibly supply 210 tons daily is the Bangpakong River. However, there is a seasonal variation in salinity of the river water (0.2 ppt to 28.5 ppt) that ranges beyond the limits that can be tolerated by the larvae of the freshwater prawn, Macrobrachium rosenbergii (about 8 ppt to 20 ppt under mass culturing conditions). The river remains high in salinity, 22.4 ppt to 28.5 ppt, from January through May, and low in salinity, 0.2 ppt to 0.4 ppt, from July through October. Salinity drops from about 25 ppt to 5 ppt in June and rises from about 0.2 ppt to 21 ppt during November and December. Thus, only two or perhaps, at the most three rearing cycles can be run in a year.

The production limitation caused by the seasonal salinity variations of the Bangpakong River can be overcome by installing water storage facilities at the station. This can be done easily by sealing the dirt bottom of each of the fifty-four (160 ton) research tanks with a concrete slab. About 8 640 tons of water can be stored in these tanks at one time. High salinity water of 28.5 ppt can be stored in May. Water directly from the river can be used during most of June and high salinity (stored) water can be mixed with low salinity river water during July, August, and September. Low salinity water of 0.2 ppt can be stored in October. Water directly from the river can be used during most of November and December, and stored low salinity water can be mixed with high salinity river water during January, February, March, and April. This cycle can be repeated yearly, barring some unforeseen weather conditions that may change the predictable seasonal salinity variation of the Bangpakong River. Through proper mixing (at higher or lower salinity levels depending on the salinity of the stored water and the river water, but within the salinity range that can be tolerated by larval prawns), and wise management of the use of the water, at least eight rearing cycles are possible annually. Eight cycles are possible because 8 640 tons of stored water mixed with 8 640 tons of river water adds up to a total of 17 280 tons of mixed water. At a water usage rate of 210 tons daily, 17 280 tons will last for 82 days. This can be done twice a year for a total of 164 days. Also, 90 more days can be added to the 164 days when the Bangpakong River is brackish in June and again in November and December, and can be used directly for larval rearing. Allowing 30 days for each rearing cycle (actually more than is necessary) 8.46 cycles can be completed in 164 days. Since 6.25 cycles are required to produce 20 000 000 PLs annually, a safety margin of 2.21 cycles is reserved for unforeseen rearing problems.

The estimated cost of slabbing the bottoms of each experimental tank with concrete is about 30 000 baht. Thus, 1 620 000 baht are required for all 54 tanks.

The larval rearing tanks must be cleaned, etched with muriatic acid, and recoated with polyester resin. This is to facilitate cleaning and disinfecting of the tanks after each rearing cycle. The estimated cost of this work is about 4 700 baht per tank, or 188 000 baht for all 40 larval rearing tanks.

Brine shrimp, Artemia sp. is proven to be the only reliable feed for rearing larval prawns on a mass scale. Substitutes are being researched by many workers, but as yet, none have equalled the quality of brine shrimp as a food source for larval prawns.

A technique to hatch brine shrimp eggs is recommended in APPENDIX A. It is based on hatching tests conducted at the Anuenue Fisheries Research Center in Hawaii. Please note that treatment concentration, treatment time, hatching time and hatching media (salinity) must be adjusted according to the best hatching response from the various brands (sources) of egg that are available from commercial sources, i.e. one must be aware that there is a difference in response (hatchability and viability) to treatment concentration, treatment time, hatching time and hatching media between brands and also between lots of the same brand.

The cost of brine shrimp eggs required to produce 20 000 000 PLs annually at the Bangpakong hatchery is 1 687 500 bhat. This cost is based on a requirement of 1 125 kilograms annually, at a cost of 1 500 bhat per kilogram.

Additional savings may be realized by growing the nauplii of the brine shrimp for two or three days. Extreme care must be taken to minimize mortality when using this technique since mortality can often cancel gains from expected added growth. The brine shrimp are grown in brackishwater of about 17 ppt.

A mixed culture of Phaeodactylum spp., Nitschia spp., and Cymbella spp., is used as feed to grow out the brine shrimp. The water is fertilized with NPK (15-15-15), at 400 g/19 metric tons, and disodium salt of EDTA, at 0.001 M. Other fertilizer combinations, such as urea, ammonium sulphate, and super phosphate can be substituted.

Control of organisms harmful to larval prawns has been a problem for all freshwater prawn hatcheries in the world. The “green water” system of larval culture successfully utilized in Hawaii to control population blooms of harmful organisms and a buffer for ammonia buildup has not been too useful for other hatcheries for some unknown reason(s). The “green water” in Hawaii is a mixed culture that is predominantly Chlorella spp. of a density of about 750 000 to 1.5 million cells per milliliter. A fertilizer solution composed of 4:1 ratio of urea to NPK (15-15-15), at 350 g/19 metric tons, is mixed with tap water and dispensed at least once a week to fertilize and sustain the “green water”. Tilapia are held in the tank to graze and control filamentous algae in the tanks. The “green water” culture at the Bangpakong hatchery tends to shift from a predominantly Chlorella, to a predominantly unknown algal culture, presumably a “blue-green” algae that occurs as paired cells of about 0.07 mm in size. Attempts should be made to provide a better media for Chlorella by manipulating the nitrogen/phosphorus ratio for best response. Urea, ammonium sulphate, and superphosphate can be used for this purpose. Addition of disodium salt of EDTA at 0.001 M or less may help.

The larval rearing tanks, green water tanks, and water storage tanks should be routinely disinfected with chlorine at a concentration of about 1 ppm. Sodium hypochlorite, or “Chlorox”, can be used for this purpose. The treated tanks must be rinsed, dried in the sun for at least one day, and rinsed again before reusing. Failure to routinely disinfect the tanks usually results in massive population blooms of organisms harmful, to larval prawns.

The chlorine treatment only minimizes the occurence of organisms harmful to larval prawns, i.e., it is not an eradication treatment. These population “blooms” of jellyfish, hydroid (both in the medusae and hydra forms), zoothamium, Epistylis, and Suctoria may occur from time to time. In this case, the standard formalin treatment of about 15–20 ppm should be applied. In the event that the formalin treatment is not too effective in controlling the hydroid, the healthy larvae should be transferred to new tanks for rearing at ten-day intervals, or more often if necessary. Mortality from hydroid infestation can be significantly reduced by using this method.

Berried females collected from farms and natural waters, and brought into the hatchery for hatching of eggs must be routinely treated with formalin at 15–20 ppm, or with copper at 0.6 ppm for 6 hours.

The introduction of organisms harmful to larval prawns is unavoidable when natural waters, i.e., water from rivers, streams, bays, etc., is used as the culturing media. The only alternative is to use water from a deep well. In view of this, a test bore was drilled to a depth of 53 meters at the Bangpakong hatchery site. At the present time water from this test bore is being tested by means of a bioassay, to see if it is suitable for rearing larval prawns. Should it be concluded by these tests that the water from the test well is suitable, every effort should be made to bore two production wells. Funds for the production wells should be appropriated now, and allotments for expenditure should be made as soon as the water from the test bore is proven to be suitable as a rearing media for larval prawns.

Chemical analysis of water from the Bangpakong test well, Banpakong River, and two private wells that are not more than two kilometers from the station is presented in Table 1.

Production of PLs from the Bangpakong hatchery can exceed the goal of 20 000 000 annually if well water instead of river water is used for culturing larval prawns. A higher production is possible because, by using well water, pathogenic organisms will not be introduced into the hatchery system. The importance of using well water cannot be over emphasized.

The budget for the attainment of the objectives presented earlier is summarized below.

Summary of Supplemental Budget for
Bangpakong Hatchery for Production of 20 Million PLs

From what can be interpreted from the two-day workshops held in Bangpakong on 1–2 May 1978, and my visit to the Songkhla Fisheries Station, the larval rearing problems existing in Songkhla are very similar to those of Bangpakong. These problems can be categorized into six general areas. They are water quality “green water” culture, disease control, sanitation procedures, and programme management. Therefore, except for capital improvement projects for Bangpakong, all recommendations made for Bangpakong in the six general categories will also apply to Songkhla. In addition, because it was very difficult to pinpoint or substantiate the reported problems, a programme to clearly identify these problems may be required before corrective measures can be recommended. For example, it was mentioned that the freshwater from the municipal water system may harbour some toxic material. If there is reason to believe that this is true, it must be substantiated. A simple method would be to conduct a bioassay, i.e., rear larvae in municipal water mixed with seawater, and freshwater from another source mixed with seawater, and compare the results, such as survival and growth between the two. The municipal water, being chlorinated, should be vigorously aerated in a storage tank, under direct sunlight for 3 to 5 days before it is used for rearing.

It was reported that the “green water” at Songkhla had a cell count, or density of about 20 million per milliliter. This cell count should be reduced to about 1 million per milliliter by means of dilution. Also, efforts should be made to reduce the “blue green” algae population and increase the chlorella population in the “green water” culture by manipulating the nitrogen/phosphorous balance and salinity (within the 8 to 20 ppt range). Tests should be conducted to find the best fertilizer-salinity combination for a high Chlorella concentration in the “green water” culture.

It was mentioned that berried females are not available all year round for hatching of eggs and culturing of larvae because of their seasonal occurrence in the lake. It might be advantageous to hold mature male and female prawns at the station for mating purposes. Berried females will be available all year round if this is done, and the recommended rearing tests can be conducted continuously to solve rearing problems. Existing tanks can be assigned for this purpose. If none are available, new tanks should be constructed to serve this purpose.

It is highly recommended that a cooperative agreement or contract be signed by the Government of Thailand and private farmers in developing freshwater prawn farming as a viable new industry. This agreement should clearly state the responsibilities and liabilities of both parties for the purpose of preventing any misunderstanding between participating farmers and fishery officers representing the Government. It will also give the fishery officers a clear-cut official status when helping farmers out in the field and the farmers will be more serious about carrying out their responsibilities.

Each farmer should be able to manage his farm by himself in three years and become independent of direct government assistance at that time. The extension service programme must be scheduled to attain this objective with each farmer. Therefore, the cooperative agreement should be in effect for only three years. The farmer should be able to profitably operate his farm in three years and afford to buy PLs from the government or private hatchery. Justification for extension of this agreement should be only disasters, such as flood and drought.

The long-term aquaculture programme of Thailand must include a plan to construct a pilot prawn hatchery near the sea where an unlimited amount of seawater of very high quality is available. The site must also be near a good source of high quality freshwater. Such a site was found near Pattaya and this site is known to the staff members of the Bangpakong Station. The salt and freshwater from this site should be analyzed as soon as possible to determine the deviation of ions from the ion composition of salt and freshwater of the Anuenue Fisheries Research Center in Hawaii. If it is found that there is no significant deviation, a very modest hatchery consisting of about twelve one metric ton capacity tanks should be constructed immediately to further test the suitability of the site for a full-scale production hatchery.

In the event a conclusion is reached to construct a full-scale production hatchery at that site, the Bangpakong Station can be converted into a training center for prospective farmers with very little additional cost. Existing facilities and proximity to farmers make it an ideal place to locate a training center.

APPENDIX A

METHODS TO MAXIMIZE UTILIZATION OF BRINE SHRIMP
IN A PRODUCTION HATCHERY FOR MACROBRACHIUM ROSENBERGII

by

Rebecca Bishop

Near the end of the 1975 hatchery season, the supply of Grade A brine shrimp eggs had run out, and there was no source for replenishing it. The hatchery personnel began using inferior quality eggs, and immediately ran into problems when insufficient quantities of viable nauplii were produced to keep the larval prawns well fed.

Some initial studies were made using borax, baking soda, epsom salts, and MgSO₄ treatments in an attempt to increase the hatchability of the eggs, or to raise the hatch density. No treatment was found to significantly or consistently increase hatch, but a maximum hatching density of 2 gm/1 was established (Utah-Longlife). Based on this information, the brine shrimp hatching procedure for the 1976 larval rearing season was amended by doubling the number of hatching containers per tank, and increasing by 1/3 the number of eggs hatched/tank/day. The hatchery survived in 1976 season, in that it produced the required number of PL's but the requirements of the 1977 season were almost double, and the quality of the available brine shrimp eggs was less than half as good. Thus, we rather frantically began searching for functional solutions.

Further studies were made on the previously tested substances and we tried separation of viable and inviable eggs in fresh H₂O, various hatching container shapes and tetracycline treatment of the hatching medium. It was suggested that we try a pre-hatch soak of the eggs in a chlorine solution. The suggested treatment was one or two drops of chlorox/liter H₂O for five minutes with a 0.05% Sodium thiosulfate rinse to dissipate the C1₂.

All experiments were run in 500 ml separatory funnels with good aeration, at room temperatures and all C1₂ solutions made from a commercial preparation of 5.25% Sodium hypochlorite. The method we used to calculate the percent hatch was to take three samples from the middle of each flask, count cysts and nauplii, and take an average. The percentage was calculated direct, with no correction factor incorporated, which may not be accurate, but it is consistent and adequate for determining the best treatment on a comparative basis.

EXPERIMENT I
Longlife #632 at 2 gm/liter (4/1/77)

During the 48-hour count of nauplii, it was observed that some of the previously hatched nauplii had died, and in unequal quantities. This was the first indication of secondary benefits to be gained in chlorine treatment.

The next factor we decided to examine was the desirability of separating the eggs in fresh H₂O prior to hatching.

EXPERIMENT II
Longlife #632 at 4 gm/liter (4/14/77)

The results of this test indicated that we would lose if we separated sinkers and floaters, and threw the floaters away, or if we tried to increase density even under more aseptic conditions. We ran a final test using our hatchery production system.

EXPERIMENT III
Longlife #632 at 200 gm/(20 gallon) barrel (2.93 gm/liter) 4/23/77

In the writing of this report, I have deleted most of the tests that were run as they were conducted in an unscientific manner for production purposes. The most important reason for reporting any of the individual tests is to demonstrate a procedure for determining the best treatment for any batch of eggs. In a production system, daily checks are made by visual observation and each batch (lot #) must be evaluated separately as they vary radically, even in batches from the same source. For example, from the information obtained in the initial tests, we began the 1977 season using a pre-hatch chlorine treatment of 0.5% or 10 ml chlorox/kg eggs for one-half hour. Subsequently, we discovered that 1% for one hour did not decrease hatch and did increase viability in all Longlife lots up to #638. For this lot, the contact time had to be shortened to one-half hour, but the chlorox concentration could be increased to 2% with the same results. Eventually we established a standard preliminary test to be used on all batches of eggs.

EXPERIMENT IV
Longlife #632 at 2 gm/liter (8/14/77)

Treatment #1 was a misinterpretation of verbal instructions of a chlorine treatment. Later we received a publication by Sorgeloos, Bossuyt, Laviña, Baeza-Mesa and Persoone on “decapsulation of artemia cysts” which delineated the error in the treatment we used. However, because of the volume limitations of that procedure and available equipment, we did not pursue it for use in the hatchery.

The methods we used for experimental purposes had to be amended slightly for production. All of the eggs to be treated were dumped into a plastic 20-gallon garbage can and the chlorox solution was added at a volume of at least 10:1 and stirred occasionally during the treatment period. The eggs were poured into a screen lined with nylon tricot material and rinsed with large volumes of freshwater, returned to the garbage can full of a solution made of freshwater and sodium thiosulfate at 10 g/kg of eggs, and later in a 0.05% thiosulfate solution; washed through the screen again with lots of freshwater and distributed among the hatching containers. The volume of eggs in relation to weight must be evaluated for each batch of eggs as some are twice as heavy as others. In hatchery production we kept the eggs in the hatching containers (20 gallon plastic garbage cans with aeration agitation provided by air rings made of 1/2 inch air line with holed drilled 1" apart on alternate sides) for 1-1/2 days, and grew them out for 24 hours in 300 or 600 gallon containers on a growout medium of Phaeodactylum tricornatum.

We ran experiments earlier in the winter to see if we could observe gross advantages of one growout medium over another in the short 1-1/2 day growout period. Our results concurred with the available literature; naked diatoms are best. We found that equally prolific diatom cultures were obtained using an enrichment of commercial 15-15-15 (NPK) and Na₂EDTA (maintained at a concentration of 0.001M) as we could get with the usual complicated and expensive enrichment solutions usually recommended for specific phytoplankton culture.

I made brief reference to the secondary effects of chlorine treatment, but in fact those are possibly the most important. We are not even sure that the chlorine actually improves the hatchability of the eggs, or if it only improves the viability of the nauplii that do hatch by destroying the potentially dangerous micro-organisms always associated with brine shrimp eggs. Thus, the greater the gains, the dirtier the eggs. Our larval rearing tanks remained much cleaner throughout the 1977 season and survival was higher than in previous years, and we feel this to be due largely to the fact that we introduced many fewer foreign organisms on a daily basis with the brine shrimp feedings. Another problem we had in the prawn hatchery was eliminated, that being large numbers of water boatman which prey upon and compete with prawn larvae. The boatman eggs come in with the brine shrimp eggs, but nearly all are made inviable by the Cl₂ soak. The gains from any of these benefits appear to be greater than the extra expenditures of labour required to treat the eggs. Because of the gains from sterilization, we have used the most extreme treatment the eggs are able to tolerate, and in choosing between high conc-short contact time vs. low conc-long contact time, we selected the longest time possible up to one hour.

Late in the summer, we were informed that we should be testing for optimum hatching salinity also. This information was in direct regard to the eggs we were using at the time. Metaframe Living World brine shrimp eggs were used for this test and the hatching density was two grams of eggs per liter of water. Test results are shown in the table which follows.

EXPERIMENT V
Metaframe Living World at 2 gm/liter

The final hatchery treatment for these eggs was 1% Chlorox for 45 minutes, and hatched in 17–18 saltwater.

This progress report represents only a step in the ongoing investigations of how to best utilize limited brine shrimp resources in a mass production aquaculture venture.