INS/85/009 Field Document 89/03 REPORT OF CONSULTANCY MISSION ON THE DEVELOPMENT OF ARTEMIA CULTURE IN INDONESIA TABLE OF CONTENTS

WIM TACKAERT
ARTEMIA CONSULTANT

Shrimp Culture Development Project
UNITED NATIONS DEVELOPMENT PROGRAMME
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS

Hyperlinks to non-FAO Internet sites do not imply any official endorsement of or responsibility for the opinions, ideas, data or products presented at these locations, or guarantee the validity of the information provided. The sole purpose of links to non-FAO sites is to indicate further information available on related topics.

This electronic document has been scanned using optical character recognition (OCR) software. FAO declines all responsibility for any discrepancies that may exist between the present document and its original printed version.

TABLE OF CONTENTS

1. INTRODUCTION

2. PROCESSING/QUALITY CONTROL OF ARTEMIA CYSTS

2.1 Demonstration Using Cysts from East Timor

2.2 Recommended Cyst Drying Methods

2.3 Storage of Cysts

2.4 Cyst Quality Determination

3. SURVEY FINDINGS

3.1 Introduction

3.2 Overview

3.3 Traditional Salt Fields

3.3.1 Semat, Jepara, Central Java

3.4 Industrial Salt Works

3.4.1 “Trapsysteem”

3.4.2 “Tafelsysteem”

3.3 Sub-center for Coastal Aquaculture Research

4. PROGRAM FOR ARTEMIA PRODUCTION

4.1 Semat, Jepara, Central Java

4.4.1 Overview

4.1.2 Proposed program (September to October 1989)

4.2 “Trapsysteem” Saltworks

4.2.1 Overview

4.2.2 Proposed program (next dry season)

4.3 “Tafelsysteem” Saltworks

4.3.1 Overview

4.3.2 Proposed program (October 1989 to May 1990)

4.4 Possible Cooperation with Research Sub-center in Gondol

LIST OF FIGURES

Figure 1. Prototype Fluidized Bed Dryer

Figure 2. Schematic Drawing of Fluidized Bed Dryer for Artemia Cysts

Figure 3. Schematic Drawing of Rotary Dryer for Artemia Cysts

Figure 4. Set-up for Putting Artemia Cysts under Inert Atmosphere

Figure 5. Schematic Sketch of a Typical Saltstreet of a Traditional Saltfield (Semat, Jepara, Central Java)

Figure 6. Industrial Solar Saltwork in Gresik, East Java

Figure 7. Schematic Layout of a Typical Saltstreet of the Industrial Saltwork in Gresik, East Java

Figure 8. Industrial Solar Saltwork in Pamekasan

Figure 9. Industrial Solar Saltwork in Sampang

Figure 10. Schematic Outline of Artemia Pond Facilities in Gondol

Figure 11. Sampling Net for Density Determination of Artemia

Figure 12. Double Screen Dip Net

Figure 13. Conical Net for Artemia Biomass Harvesting

LIST OF ANNEXES

Annex 1. Itinerary and Program

Annex 2. Materials/Equipment for Harvesting, Processing and Quality Analysis of Cysts

Annex 3. Conversion Table for Various Units of Salinity

1. INTRODUCTION

This report describes the results of a 3 weeks consultancy mission to the Shrimp Culture Development Project INS/85/009. During this mission the following activities were performed:

• provide guidelines/demonstration of Artemia cyst processing techniques;

• provide guidelines/demonstration of techniques for quality control of Artemia cysts (hatching quality, moisture content);

• survey of traditional (Semat, Jepara, Central Java) and industrial (Gresik, E. Java; Sumenep; Pamekasan; Sampang, Madura) solar salt fields in order to evaluate their potential for integrating Artemia culture in their operation;

• visit and evaluation of Artemia research facilities of the Research Institute for Coastal Aquaculture Sub-center in Gondol, Bali;

• visit various backyard (Jepara district) and industrial scale (Jepara district, Situbondo district) penaeid hatcheries.

The itinerary and day-to-day schedule of the mission are summarised in Annex 1.

The purpose of this report is as follows:

• to provide recommendations for processing and quality control of Artemia cysts;

• to give a review of the lay out, brine flow, and salt production principles of both traditional and industrial salt works visited;

• to give an overview of existing outdoor Artemia production facilities visited;

• to identify potentials and constraints for extensive culturing of Artemia cysts and biomass integrated with the different solar salt systems; and;

• to provide a program for the development/optimization of Artemia production at the different locations visited.

2. PROCESSING/QUALITY CONTROL OF ARTEMIA CYSTS

2.1 DEMONSTRATION USING CYSTS FROM EAST TIMOR

During our stay, small and large scale processing of cysts, collected from Lake Laga (E. Timor) was demonstrated. Cleaning of cysts including size separation/washing (over different screens) and density separation was done according to the procedures outlined in the “Artemia Manual” by Sorgeloos et al. (1986) and will not be discussed here. After cleaning the cysts were squeezed in a 150 μm screen bag in order to remove fresh water

For drying, the cysts were granulated by hand through a screen of about 3 mm and spread in uniformly thin layers (few mm) on a 150 μm screen mounted in a tray. Two different drying methods were evaluated. In the first method the trays were placed in a cabinet dryer at ambient temperatures. This cabinet dryer, which is normally used for drying of pellets consists of a closed cabinet which holds several trays arranged in such a way to create optimal circulation of the air coming from a perforated PVC pipe (placed underneath the racks) connected to a blower. In the second method, the same racks containing the same quantity of cysts were placed in a room at ambient temperature. Air circulation and consequently drying was enhanced by a domestic fan directed towards the drying racks (fan dried cysts). In both methods the cysts were regularly redistributed (brushed) over the racks in order to enhance uniform exposure of the cysts to the air.

Determination of moisture content in dry cysts (according to standard method outlined in the “Artemia Manual”) revealed an acceptable 8.31% of water for the fan dried cysts, while in the cabinet dried cysts it was as high as 26.7%. Since the water content of the cysts should be below 10% in order to arrest their metabolic activity, it is expected that the hatching quality (especially after storage) of the cabinet dried cysts will be considerably inferior than for fan dried cysts. Therefore it is suggested that for the time being, drying of cysts be performed following the fan drying method. It is to be verified however if this method will still be suitable in the rainy season when ambient humidity will be much higher than under present dry season conditions. In addition, layer drying of cysts is also less suitable for processing of the larger quantities of cysts expected to be produced in Madura (see further) since it requires a lot of space. Therefore fluidized bed drying or rotary drying should be considered.

2.2 RECOMMENDED CYST DRYING METHODS

Fludized bed or rotary drying makes possible uniform drying of cysts to a low water content (less than 5%) in a short time interval (few hours) resulting in a better hatching quality and shelf-life of the cysts. Figures 1 and 2 give a schematic outline of a fluidized bed dryer (FBD) with a capacity of about 0.5 and 2 kg dry weight, respectively. The vertical part of the FBD can be made of PVC pipe in which transparent (plastic) windows are provided to monitor how dry the cysts are based upon the degree of lifting. Figure 3 gives a schematic drawing of a rotary dryer. Drying capacity of a 100 1 drum rotated at about 10 rpm amounts to 10–20 kg per 3 hours depending on air circulation (e.g. from a fan directed towards the opening of the drum), temperature and air humidity. Sticking of cysts to the wall of the drum can be prevented by adding marbles.

Figure 1. Prototype Fluidized Bed Dryer.

¹ conical shape results in differences in air pressure and assures better mixing of the cysts

² more pressure is needed at the start (heavy cysts containing much water before dehydration) than at the end (light cysts with low water content) to keep the cysts suspended in the drying chamber.

Figure 2. Schematic drawing of fluidized bed dryer for Artemia cysts.

Figure 3. Schematic drawing of rotary dryer for Artemia cysts.

Best results for both drying methods are obtained at higher temperatures (which however should not exceed 40°C), e.g. by heating the incoming air or by placing the drying devices in a thermostatic room at about 35°C. Although in both methods, temperature readings of incoming and outgoing air may give a rough indication of the drying rate of the cysts, it is advisable to perform regular analysis of moisture content of the cysts after different time intervals in order to standardize the time of drying (function of quantity of cysts and rate/temperature/humidity of incoming air). The quantity of cysts to be dried per batch should be adjusted in order to obtain a cysts moisture content of less than 5% in 3 hours. Standardization of drying procedures should be done both in the dry and wet season (different air humidity conditions).

2.3 STORAGE OF CYSTS

Dried cysts may be stored in sealed plastic bags. For better storage it is advisable to replace the air in the bag by flushing the cysts with H₂O - free N₂ - gas. Closed bags should be stored in a dark dry place (e.g. in a bin containing silica gel) or in a refrigerator/freezer. Under the latter conditions diapauze in cysts originating from Great Salt Lake inoculations (as in Lake Laga) will be inhibited resulting in optimal hatchability (see further). All processed batches of cysts should be labeled properly. The label should give information (or refer to) on the production conditions including pond conditions and origin of inoculation material, date and procedure of processing, and possibly also moisture content and hatching quality of the cysts.

Larger quantities of cysts should preferentially be canned and vacuum flushed with N₂ to guarantee optimal storage of the cysts. For this unsealed cans containing dry cysts are placed in an air tight firm box connected to a vacuum pump and N₂-bottle (see Figure 4). If vacuum is complete (read from a manometer) the connection to the vacuum pump is closed and the box is flushed with N₂ from an inlet connected to a nitrogen bottle. When the box is fully filled with N₂ its cover is removed and the N₂ filled cans are taken out for sealing. Processing of cysts (including drying and packing) may be performed in Jepara and/or Sumenep (when large quantities are produced from the brine reservoir).

2.4 CYST QUALITY DETERMINATION

During the visit a new method (adapted from the standard methods described in the “Artemia Manual”) for combined determination of hatching efficiency (HE) and hatching percentage (H %) was proposed.

The procedure is as follows:

1. Incubate 500 mg of dry cysts in 400 ml 35 ppt seawater under continuous illumination, provided by fluorescent day light tubes, at ambient temperature in an inverted plastic water bottle (620 ml). Provide point aeration from the bottom as to keep all cysts in suspension. Run test in triplicate.

2. After 1 hour, adjust volume to 500 ml by adding 100 ml of 35 ppt seawater. Place a reference mark for 500 ml volume.

Figure 4. Set-up for putting Artemia cysts under inert atmosphere.

3. After 24 hours add seawater up to reference mark to compensate for evaporation. Take 10 subsamples of 0.5 ml each, with a glass pipet from which the tip has been cut away.

4. Pipet subsamples in small petridishes and fixate nauplii by adding a few drops of Lugol's solution. Count nauplii in each petri dish and calculate the mean value, , per hatching tube and the overall mean for the 3 hatching tubes (N).

5. Calculate HE (24 hr) as follows : HE = N×2×2×500

6. For determination of H% (24 hr), decapsulate unhatched cysts and dissolve empty cyst shells by adding one drop of NaOH (40% solution) and about 5 drops of sodium hypochlorite (10% active chlorine). Count unhatched (orange colored) embryo's (c₁) and calculate mean value ().

7. The same procedure (3–5) can be repeated for determination of HE and H% after 48 hr (adjust volume in hatching bottles prior to taking samples).

The Lake Laga cysts after processing revealed very low hatching. This can be explained by the fact that the cysts used for inoculation (OSI 80) originated from Great Salt Lake, which requires additional treatment in order to arrest its diapause and eventually give optimal hatching. This can be obtained by storing the cysts in a freezer for at least 1–2 months or by incubating the cysts for about 15 minutes in a 5% H₂O₂ solution prior to hatching (see also Artemia Manual). Determination and extrapolation of quantity of processed cysts collected from a 1 m shore transect (from a total of 250 m) at Lake Laga revealed that the total production capacity of the lake is about 14 kg of dry cyst.

Materials/equipment required for processing and quality analysis of cysts is listed in Annex 2.

3. SURVEY FINDINGS

3.1 INTRODUCTION

This chapter gives an overview of the different types and production principles of the solar salt works visited. In addition, potentials and constraints for integration of Artemia production are discussed.

The survey team consisted of the writer and Ms. Caroline Raymakers, APO/Artemia Culturist, INS/85/009. At Gresik, Sumenep, Sampang and Pamekasan the team was accompanied by Jr. Momo Ratmawidjaja, Technical Director, and the production managers of the respective industrial solar salt works.

3.2 OVERVIEW

The total area for solar salt production in Indonesia is about 32,000 ha, with the majority located in Java and Madura. About 18,000 ha are “Garam Rakyat” privately owned artisanal saltworks, while 6,000 ha, located in Gresik and Madura, are operated by the Ministry of Industry. It should be noted that the latter were started by the Dutch long before Indonesian independence. For this reason all the terms used are in Dutch, a practice which persists up to the present.

The artisanal saltworks are mostly very small and have low yields (about 20 ton NaCl/ha/year), the industrial salt works are large (450 to 3,000 ha) and have adopted modern techniques for solar salt production, e.g. use of pumps, build up of salinity gradient over a series of successive evaporation ponds for precipitation of carbonates and gypsum prior to the transfer of brine to crystallizers for depositing of pure sodium chloride (NaCl); use of a salt floor to facilitate harvesting of clean NaCl, drainage of remaining bitterns, etc. As a result NaCl purity from industrial salt works attains 95 to 97% as compared to only 90% for the salt produced in the traditional systems.

Similarly, yields from the industrial saltworks are much higher (30 to 60 tons NaCl/ha/year) than those obtained from the artisanal saltworks. Total yearly production from industrial and traditional systems amounts to approximately 330,000 and 600,000 tons respectively.

Small quantities of salt are also produced by boiling of brine, extracted from salt saturated soils (East Timor, Flores), and by exploitation of salt crusts remaining after periodical drying out of salt lakes (Lake Laga, East Timor). All salt from the artisanal saltworks is used for human consumption (note that the standard for common edible salt in Indonesia is 95%), while part of the industrial salt is used in the chlor-alkali industry (after washing to attain a purity of 98.5 required for grade II industrial salt) and in the petroleum industry (uses salt in drilling mud when underground salt formations are anticipated). Every year Indonesia is importing an additional 100,000 ton of salt from Australia for industrial purposes.

3.3 TRADITIONAL SALT FIELDS

3.3.1 Semat, Jepara, Central Java

The total area for salt production in Semat is approximately 320 ha producing about 6,500 tons of salt per year. Salt is produced in the short dry season from June to October. This year the dry season has been extremely late (the rains stopped only by the beginning of August) resulting in a serious delay in salt production.

A typical saltworks in Semat consists of about 3 saltstreets (i.e. a separate unit for salt production) each with a size of 1 ha. A lay out of a typical saltstreet is given in Figure 5. It consists of a series of about 20 ponds (more or less of equal size) which are surrounded by a 2 m wide canal which serves as a reservoir. Due to this year's unfavorable climatic conditions only a part of the ponds is being used for salt production. The seawater/brine circuit is as follows: from the reservoir (filled by tidal action) the water is pumped (by a wooden windmill) into a small supply canal from where the water flows by gravity into the evaporation ponds. When the salinity in the evaporators reaches about 70 to 80 ppt, water is transferred (via the supply canal) to the crystallizers by manually scooping the water using a traditional wicker-type of scoop mounted on a long pole.

Figure 5. Schematic sketch of a typical saltstreet of a traditional saltfield (Semat, Jepara, Central Java).

Generally, there is no transfer of brine among the evaporators. As a consequence the evaporators do not exhibit a salinity gradient for gradual precipitation of salts with lower solubility than NaCL, as is the case in modern solar salt making. Brine in the crystalizers (layer of a few cm) is left to dry out completely. The thin layers of precipitated salt are harvested directly from the bottom. Normal water depth in the evaporators is about 20 cm (upon filling with seawater) to 10 cm (after evaporation, prior to transfer) resulting in maximum temperatures of up to 40°C.

In one saltstreet BBAP is operating 3 ponds for Artemia production. In order to create more suitable conditions for Artemia culture (i.e. water temperatures lower than 35°C; promotion of phytoplankton instead of undesirable phytobenthos, not available as food for Artemia) the ponds have been modified by digging an inner perimeter ditch of 1 m wide and 50 cm deep resulting in a maximum water depth of 20 cm in the central part and 60 to 70 cm in the ditch.

Due to previously excessive rainfall the pond salinities reached only 70 ppt by the end of August. Repeated trials to introduce Artemia under this low salinity conditions were unsuccessfull due to the presence of diving water beetles and insect larvae preying on Artemia. The water beetles, which were observed to hide and breed in the phytobenthos, were a real pest. After the first week of September, however, when the salinity had increased to more than 80 ppt, all insects had disappeared.

Though the ponds were regularly fertilized with inorganic fertilizer, (urea and super triplephosphate at a rate of 12 and 6 ppm respectively) and organic (bat dung) fertilizer a real phytoplankton bloom never established. Instead, algal mats and floating algae were flourishing abundantly. Nutrient analysis of the pond water revealed very low levels of ammonia and nitrate, while phosphate was quite high (2.2 ppm). In addition, no differences were observed in nutrient levels of the unfertilized reservoir and the fertilized ponds, indicating that the fertilizer was indeed trapped in the bottom and converted to algal mats. This is probably due to insufficient water depths allowing full penetration of sunlight to the bottom, and poor availability of fertilizer in the water column owing to incomplete dissolving of fertilizers upon application, increasing the capacity of the pond mud to absorb plant nutrients. Also the fact that the ponds are not operated in a flow through, thus presenting a very static system, may have depressed the growth of phytoplankton.

In conclusion it may be stated that this type of traditional salt ponds present only a limited potential for commercial production of Artemia. The dry season is quite short and not always consistently dry. Moreover, since the ponds are not operated under flow-through conditions, it may take up to 2 months in order to obtain desirable conditions for introduction of Artemia in modified ponds, leaving only 2 more months for actual Artemia production. In addition, the modified ponds are not available for salt production, during the majority of dry season, thus further reducing the already poor outputs of salt.

Despite their limited potential, it is however advisable to further operate (at least this year) the modified ponds for Artemia culture so as to get acquainted with the Artemia pond management techniques. A detailed program of activities is presented in chapter IV of this manuscript. Due to their proximity to BBAP, the modified ponds could also serve (in the next years) for demonstration of salt cum Artemia production to technicians being trained at BBAP.

3.4 INDUSTRIAL SALT WORKS

3.4.1 “Trapsysteem”

i. Gresik, East Java

This medium size salt work of about 450 ha located at Gresik (West of Surabaya, E. Java) and operated by the Ministy of Industry, consists of two large reservoirs (“Buzem Lama”, 88 ha; Buzem Barat, 65 ha) and numerous rectangular saltstreets (i.e. separate units for saltproduction) each with a size of about 1 to 2 ha (see Figure 6). The reservoirs are filled by tidal intake from where the water is pumped into the “jong water” canal which serves the evaporation ponds (usually in series of 5). In the evaporation ponds the salinity is gradually build up until it reaches about 24 °Be (see Annex 3 for conversion table of various units of salinity) in the last evaporation pond. At this point the brine is drained into the “loog canal” from where the crystallizers (six ponds usually in series of 3) are served. Lay out of a salt street and adjoining canals is presented in Figure 7.

In the crystallizers the brine is further concentrated until most NaCl is deposited. At this point (i.e. at a salinity of 29 °Be) the remaining liquid (bittern) is drained into the bittern canal and returned to the sea. In the crystallizers a thin saltfloor (3 cm) is established allowing for salt over salt harvesting resulting in a higher purity of the salt collected. Usually the crystallizers are harvested about every 2 weeks. After each harvest the salt floor is scarified (“afvlakken”) as to prevent sticking of the new salt layers to the salt floor. Normal production of this saltwork amounts to 12,000 tons per year. Salt purity attains 95%. Depth of the evaporators ranges from 10 to 20 cm. pH and temperature (around noon) in the evaporator ponds recorded during our visit were 8.7 (at a salinity of 9 °Be), 39°C respectively. At the beginning of the dry season the salinity in the successive evaporators normally ranges from about 5 to 8°Be. As the dry season proceeds the salinities are gradually increased as to establish a salinity gradient from 11 to 24°Be, the point at which carbonates and most gypsum (CaSO₄) have precipitated and NaCl deposition is initiated.

As a result of excessive rains during this production season, the salinity gradient during our visit (end of August) ranged from 4 to 9°Be only. As a consequence part of the crystallizer area (3 ponds) was also used for further evaporation and brine concentration as to reach sufficiently high salinities (24–25°Be) essential for crystallization of NaCl. As is the case in the traditional saltfields, shallow water depths imposing lethal high temperatures for Artemia, prevent the establishment of Artemia culture unless the ponds are modified. As compared to Semat, this region however offers better climatic conditions (i.e. the dry season is more pronounced), which more justifies the adoption of modified ponds for Artemia culturing. A detailed program for development of Artemia production in modified evaporation ponds is presented in chapter IV.

Figure 6. Industrial solar saltwork in Gresik, East Java.

Figure 7. Schematic layout of a typical saltstreet of the industrial saltwork in Gresik, East Java.

3.4.2 “Tafelsysteem”

i. General description

The “Tafelsysteem” salinas located in Madura are basically large saltworks consisting of one or two reservoirs (“Buzem”), a series of evaporation ponds, a brine tank and one crystallizer complex divided in several crystallizer beds. The lay of the large ponds and brine flow are largely based on the elevation contours and topography of the land. The reservoir is located in the lowest land near the sea while the crystallizers are located at the highest elevation as to facilitate quick drainage. The reservoir is filled by tidal intake, controlled by a 2 way sluice. From the reservoir the water is pumped into the “jong water” canal from where the evaporators are served.

The evaporators are operated in series. To build up a graded density, the evaporators are provided with gates to control flow between ponds. The larger evaporation ponds are divided by inner bunds in order to make the brine travel over a larger distance, as brine in motion evaporates more quickly than in stagnant condition. Among the evaporators the brine concentration is progressively raised from about 4°Be to 24°Be (in the last evaporation pond). At this point brine is pumped or gravity drained into a brine tank where the concentration is maintained at 25 °Be (to aid in complete deposition of gypsum which has a tendency to supersaturate).

From the brine tank the water is relifted or drained into the “loog” canal which serves (by gravity) the rectangular crystallizers. From the crystallizers the remaining bittern is drained back to the sea via a bittern canal. As in Gresik a thin saltfloor (3 cm) is established in the crystallizer beds to facilitate subsequent harvesting (every 2 weeks) of salt. The salt (like in all other solar saltfields in Indonesia) is harvested by hand (with some kind of shovel/scraper) placed in 50 kg baskets and placed on the workers head who walk to the edge of the crystallizers where the salt is piled to drain. In the “Tafelsysteem” salt works the salt is then transported by truck (Sumenep) or side dump trailers pulled by a locomotive (Pamekasan, Sampang) to the storage and/or iodization or washing plant where the salt is eventually sacked.

Each “Trapsysteem” salina has 2 or 3 deep brine reservoirs which are used to store the remaining brine pumped from the evaporators at the end of the salt production season (October-November). Throughout the rainy season the brine concentration is kept constant by regular decanting of freshwater layers statified on top of the brine through several large gates. By the beginning of the dry season (mid May) the brine is drained back to the evaporators.

Salt yields from the “Tafelsysteem” saltworks are much higher (i.e. up to 60 ton/ha/year) than in the “Trapsysteem” and traditional saltfields. This is due not only to better climatic conditions occuring in Madura but also to the application of more modern techniques for solar salt making such as the use of brine reservoirs, brine tanks, pumps, etc. Similarly the purity of the salt (i.e. 97%) is much higher than in the other systems.

ii. Sumenep

Located at the South Western coast of Madura (Kalianget), this 3000 ha saltwork which has a capacity of about 200,000 ton/year consists of the following parts : (1) reservoir or “Buzem” (16 ha), (2) evaporators (2400 ha), (3) crystallizers (280 ha - 1 ha each), (4) brine tank (20 ha) and (5) brine storage or “Loog Woduk” (85 ha). The brine storage consists of 2 ponds. The first (35 ha), which has a depth of 2 m receives its brine from the high salinity evaporation ponds and brine tank resulting in a brine concentration of 20°Be. The second brine reservoir (70 ha) is filled up to a depth of 1 m with brine of 8 to 10°Be pumped from the intermediate salinity ponds.

Due to the over-extended rainy season (rains stopped only by the end of July) the pond salinities by the beginning of September were much lower than what could be expected during a normal year, i.e. the brine in the last evaporation pond had reached a concentration of 14°Be only, where normally it should already have been 24°Be. Provided climatic conditions remain favorable, the saltwork still expects to reach the latter concentration by the end of September. This year, however, the brine will not be allowed to exceed 20° Be (i.e. through mixing with seawater from the “jong water” canal) as to yet produce the maximum quantity of salt possible. It is however to be expected that applying this procedure will result in a lower quality of salt produced. Further more as a result of the delay in salt production and mixing practices the salinities to be obtained in the brine reservoirs will probably be slightly lower than those mentioned above.

Depth in the evaporators varies between 10 and 25 cm. Maximum pond temperature observed during our visit was 37.5°C. While in the 14°Be pond no more predators were present, small fish (milkfish and probably Tilapia) were still observed in the evaporator containing 9°Be. At Sumenep a new salt washing and iodization plant has recently been put into operation. In addition to locally produced salt, this plant will also process and pack the salt produced at Pamekasan and local traditional saltfields (when prices are low the government buys the salt of the latter).

iii. Pamekasan

Located South of Pamekasan this 975 ha saltwork (see Figure 8) produces about 60,000 tons of salt/year. It consists of a relatively large reservoir (283 ha), 830 ha of evaporation ponds, 132 ha of small crystallizers pond, each with a size of 1000 m², and 2 brine reservoirs of 10 and 17 ha. Both reservoirs are filled with brine at 10 to 11 °Be to a depth of 1.5 m at the end of the dry season. Unlike Sumenep where the brine reservoirs are filled with a mobile pump, these brine reservoirs are filled from a cement side canal connected to a pump (“Loogpump”) which normally lifts the brine into the “loog canal”. This side canal can easily be provided screens as to prevent fish from entering the reservoir. This dry season, the brine reservoirs, which are normally left dry, have been filled with 30 cm of brine in order to increase the evaporation area in order to compensate for the delay in brine production due to unfavorable climatic conditions. During our visit small and medium size Tilapia were still present in the brine reservoir (visible only near the gates), though the salinity was as high as 15° Be.

Figure 8. Industrial solar saltwork in Pamekasan.

iv. Sampang

Located south of Sampang this 1,150 ha saltwork (see Figure 9) has a production capacity of 60,000 ton/year. It consists of a 186 ha reservoir, 830 ha of evaporation ponds, 132 ha of crystallizer ponds (each with a size of 100 m²) and 3 brine reservoir of 10, 16 and 11 ha with a depth of 1.5 m and salinities of 10, 7.5 and 10°Be respectively during the rainy season. As in Pamekasan, the brine reservoir are filled to obtain additional area for evaporation and production of brine. The salt produced in Sampang is shipped directly to Surabaya (for industrial purposes) and/or Sumatra and Kalimantan for use in oil drilling.

While the evaporators of the “Tafelsysteem” saltworks are probably unsuitable for Artemia production due to their shallow depths, the reservoirs however may present good conditions for Artemia production throughout the rainy season, i.e. intermediate or high salinities excluding most or all predators, deep ponds providing suitable conditions for phytoplankton production and moderate temperature for Artemia. Nevertheless, care has to be taken to prevent all predators by screening the brine at the intake. Since the brine reservoirs will present fairly stable conditions in terms of salinity, throughout the rainy season, it is expected that cyst production will be limited to a few months after introduction i.e. newly introduced population generally exhibit a good rate of cysts production initially. After that however, cyst production will probably decline significantly due to the absence of salinity shocks. It is only when algal blooms can be maintained e.g. through fertilization (providing large diurnal fluctuations in dissolved oxygen levels) that cyst production may possibly be triggered again. A program for developing Artemia production in the brine reservoirs of the “Tafelsysteem” salinas is presented in Chapter IV.

3.3 SUB-CENTER FOR COASTAL AQUACULTURE RESEARCH

Located in Gondol, Bali, this sub-center is part of the Coastal Aquaculture Research Center of the Agency for Agriculture Research and Development. Main activities consist of research on the production of penaeid shrimp, turtles and Artemia. For Artemia culture the center has at its disposition over 6,000 m² pond facility equipped with concrete dikes and canals. An outline of the pond facility is presented in Figure 10. It consists of 6 evaporation ponds, each, with a size of 1,600 m², and a series of 100 m² (24) and 200 m² (10) ponds for culturing of Artemia. Each Artemia pond is connected to a water supply and drainage canal. Water intake in the Artemia ponds from the supply canal is controlled by a turndown pipe, the opening of which is covered by a 300 pm screen. Ponds and/or canals can be filled directly by tidal intake at spring tide. Reportedly, the ponds will be used to study the effect of organic fertilizers/byproducts (as a direct or indirect food source for Artemia) on the production and nutritional quality of Artemia. This study will be performed in cooperation with a project of US AID (Prof. K. Simpson).

Figure 9. Industrial solar saltwork in Sampang.

Figure 10. Schematic outline of Artemia pond facilities in Gondol.

Actually the evaporators are not being used because they are suffering from severe water loss through the coral/sandy soil. The Artemia ponds, lined with plastic covered with a soil layer of about 20 cm, are filled with seawater to a depth of 40 cm (maximum waterdepth in the ponds is about 60 cm). Aiming at producing biomass the Artemia ponds have been repeatedly stocked with Artemia nauplii. Yet, an Artemia population never established. Though the ponds contained no fish it is likely that the inoculated nauplii were eaten by the larvae of airborne insects observed in large numbers in the ponds maintained at low salinity.

Near the experimental ponds about 6 small earthen ponds (6 m²; depth 50–60 cm) are used for the production mainly of biomass and also some cysts. These are filled with brine (50 ppt when aiming at biomass production; 100 ppt for cyst production) produced in the evaporation ponds of an adjoining abandoned traditional salt field. Stocked at 100 nauplii/l the 6 ponds together reportedly produce about 2 kg of wet weight biomass over a period of 2 weeks. In between harvests the ponds are dried. During our visit Artemia nauplii inoculated one day earlier were still showing good survival and condition. Though the salinity was only 50 ppt no insects or other predators were observed.

4. PROGRAM FOR ARTEMIA PRODUCTION

4.1 SEMAT, JEPARA, CENTRAL JAVA

4.4.1 Overview

The traditional saltfields in Semat present a very limited potential for commercial scale production of Artemia cysts and biomass as already mentioned earlier. Due to their proximity to BBAP it is however advisable that the 3 existing modified saltponds be further operated during this dry season in order to prove the technical feasibility of integrating Artemia production with traditional salt farming as well as to get acquainted with Artemia production techniques, e.g. pond fertilization, predator control, harvesting and processing of cysts and biomass, etc.

4.1.2 Proposed program (September to October 1989)

i. Pond disinfection

Application of caustic lime (CaO) and ammonium sulphate (for increased pH) at a rate of 1,000 kg resp. 100 kg/ha to ponds filled with water as to kill predators (mainly insects) and to destroy unwanted phytobenthos. Dead floating algae are to be scooped off the watersurface. In addition to disinfection, liming will also have a beneficial effect on buffering of pH (Artemia thrives best in slightly alkaline waters) and on bio-availability of nutrients for phytoplankton which serves as a food for Artemia.

ii. Water management

Regular intake of seawater (screened, 500 μm) or preferentially brine from the canal as to maintain maximum waterdepths (rate of waterintake is function of evaporation rate) and to gradually increase the salinities in the ponds (to further exclude predators).

iii. Fertilization

Apply inorganic fertilizer about 2 to 3 weeks after liming. The rate of fertilization depends on the nutrient content of the water. Generally, fertilizer should be added to attain a concentration of about 5 ppm N and 1 ppm P. Inorganic fertilizer is to be dissolved properly and sprayed equally over the water surface.

iv. Stocking and monitoring

As soon as a phytoplankton bloom is established, Instar I Artemia nauplii from San Francisco Bay will be introduced at a rate of 25 nauplii/l. Throughout the production trial the following physico-chemical and biological parameters will be evaluated at weekly intervals: temperature (minimum - maximum) ; salinity; pH; waterdepth, transparancy, watercolor, presence of predators, presence of phytobenthos/floating algae; Artemia density/population composition/standing crop. Methodologies, and interpretation of collected data can be found in the “Artemia Manual” by Sorgeloos et al. (1986) and “Semi-intensive production of Artemia in fertilized ponds” by Tackaert and Sorgeloos (1989, in press).

Artemia population density and standing crop can be determined from representative samples taken with a plankton net (see Figure 11). For sampling let the plankton net sink down to the bottom. A few minutes later the net is hauled out of the water. The Artemia concentrated in the beaker are rinsed (remove pieces of algae if present) into a small tared sieve (150 μm) weighed and counted. Artemia standing crop (gram Artemia/l) and density (number of Artemia/l) are calculated taking into account the volume of water sampled (function of diameter of plankton net and height of water column sampled). If high numbers of Artemia are present the samples are subsampled to about 200–300 animals for counting. Samples are taken at fixed sites (e.g. in the ditch along the leeward and windward side and in the central part of the pond) preferentially early in the morning when Artemia is more homogeneously distributed. The same sampling procedure can also be used for determining the Artemia population composition.

v. Pond management

The parameters mentioned above are used as basis for pond management including fertilizer dressings (based on water transparency and nutrient levels), intake of seawater/brine and rate of biomass haryesting). Ideally the biomass should be harvested on a renewable basis in order to maintain the maximum sustainable yields (among others, function of phytoplanktonic standing crop and rate of water exchange). Precise estimates of the maximum sustainable yields are however very difficult to make. However, some general guidelines for deciding upon the rate of biomass harvesting discussed below.

Figure 11. Sampling net for density determination of Artemia.

The rate of biomass harvesting is increased when there is a high (anticipated) rate of recruitment (shown by increasing animal densities, a population in which all size classes are represented, dominant ovoviviparous reproduction) and when water transparency is increasing (indicates that Artemia grazing rate is exceeding the rate of phytoplankton production which eventually may lead to a total depletion of phytoplankton resulting in starvation of Artemia). On the other hand biomass harvesting is arrested when the animal densities are decreasing and/or the population consists mostly of pre-adults and adults showing low fecundity and/or dominant oviparous reproduction. The Artemia biomass will be harvested with a scoopnet (mesh ± 800 um). Cysts are harvested from the water surface using a double screen dipnet (see Figure 12) as soon as possible after their production and accumulation in order to ensure maximum recovery and hatching quality. Collected cysts will be washed/cleaned on site with saturated brine or pond water, after which they are stored (not longer than 1 month) in a closed container filled with saturated brine. Further details on processing of cysts is discussed in Chapter II of this report.

4.2 “TRAPSYSTEEM” SALTWORKS

4.2.1 Overview

Due to the shallowness of its evaporation ponds the “Trapsysteem” at Gresik is not suitable for Artemia production unless the ponds are modified (i.e. by deepening). Modified ponds, however, require a larger volume of brine than shallow ponds resulting in a delayed and eventually decreased, production of salt. Therefore it is proposed that during the next dry season only the last evaporation pond (approximately 1,200 m²) of a typical saltstreet be modified. Since this one evaporation pond represents less than 10% of the total evaporation area it is expected that the proposed modification will not interfere with the salt production outputs.

4.2.2 Proposed program (next dry season)

i. Modification

At the onset of the dry season and prior to flooding of salt beds, modify the last evaporation pond of a typical saltstreet by digging an inner perimeter ditch of about 2 m wide and 1 m deep. Dikes and pond bottom should be carefully compacted to avoid seepage.

Figure 12. Double screen dip net.

ii. Preparation

Lime pond bottom and dikes at a rate of 500 kg Ca CO₃/ha. If soil pH is still low, wash out the acidity by flusing the pond with seawater and apply more lime as to neutralize soil acidity (see Artemia Manual). As soon as the pond is filled to the maximum level with a salinity sufficiently high to exclude predators, apply inorganic fertilizer at the same rate as proposed for the demonstration ponds in Semat.

iii. Pond management

Including dressing fertilization, harvesting of biomass and cysts will be done according to the same principles as proposed for Semat. Throughout the dry season the same flow through procedures as used in the normal salt operation will be followed.

iv. Cyst processing

Cleaning of cysts including size separation and density separation in brine will be done onsite. Further processing including freshwater washing, separation and drying will be done in Sumenep (see chapter II)

v. Biomass harvesting and utilization

Harvested live biomass may be used directly as a grow-out starter feed for P. monodon. Harvested biomass may also be temporarily stocked (up to 1 week) in nylon screen cages (meshwidth of 800 μm) which are suspended in the culture ponds. Later, if more ponds are being modified and used for Artemia production blast freezing and/or drying of biomass should be explored for use in maturation feeding of shrimp, or as a dietary ingredient in shrimp larval and postlarval diets (e.g. flakes, “egg custard”, etc.) respectively.

vi. Future activities

Based on the results of the “demonstration trial” of the first year, up to 30% of the total area could eventually be modified for Artemia production in the following years. However, then brine reservoirs should be used in order to compensate for the reduced outputs of salt i.e. storage of large volumes of remaining brine from the modified ponds (not used for crystallization) throughout the rainy season and return it to the evaporation ponds and eventually crystallizers at the onset of the dry season in order to realise a faster start up of salt production.

4.3 “TAFELSYSTEEM” SALTWORKS

4.3.1 Overview

Although the water in the evaporation ponds of this large saltworks are slightly deeper (i.e. about 20 cm) than in the traditional or “Trapsysteem” saltfields they are probably not suitable for Artemia production because they still present lethal high water temperatures (up to approximately 38°C) and low food (phytoplankton) production for Artemia.

All 3 saltworks have however deep brine reservoirs which are filled at the end of the dry season (October - November) with remaining brine from the evaporator ponds. Total area of brine reservoirs is about 168 ha. Depths and salinities vary between 1 and 2 m, respectively 7.5 to 20° be, presenting suitable conditions for Artemia. Throughout the rainy season the salinity is kept constant by decanting freshwater stratified on top of the brine through several large gates. By mid May the brine is returned again to the evaporation ponds for further evaporation and start up of salt production. The coming rainy season, work will mainly focus on the 35 ha brine reservoir located at Sumenep. Meanwhile however, and if time permits also the other brine reservoirs will be monitored and operated for Artemia production.

4.3.2 Proposed program (October 1989 to May 1990)

i. Preparation

Install screen (mesh 3 mm) to prevent fish from entering the ponds upon filling (in Pamekasan, Tilapia was observed at salinities as high as 15°Be). Once completely filled eradicate remaining fish by locally applying saponin to ponds (fish usually concentrate around the gates). Install cysts barriers (e.g. lining of dike with plastic sheet or corrugated plastic) as to prevent cysts from being washed ahore and to facilitate harvesting.

ii. Stocking and monitoring

Introduce Instar I Artemia nauplii from San Francisco Bay at low densities, e.g. 2 nauplii/1. The quantity of cysts to be incubated depends upon pond volume and hatching efficiency of the selected batch of SFB cysts (see also “Artemia Manual”). After about 3 weeks start regular monitoring of physico-chemical and biological parameters (see program for Semat).

iii. Management

When transparency readings are more than 40 cm, apply inorganic fertilizer to be distributed from the boat, at a rate of 2 ppm Nitrogen and 0.4 ppm Phosporus. Alternatively the fertilizer may be put on several platforms (about 10 cm above the pond bottom) scattered over the pond. Although organic fertilizers are generally too bulky for large scale application, their local availability and ways of distribution should be examined.

iv. Harvesting and processing

Conduct regular harvesting of biomass (rate to be determined from changes in transparancy readings and Artemia population composition/standing crop/ fertility parameters) and cysts. Biomass harvesting can be done by a large concial net (see figure 13) towed by a boat. Harvested live biomass may be used directly in local shrimp culture (grow out). In a later phase processing of biomass (e.g. blast freezing, flaking) should be explored.

Figure 13: Conical net for Artemia biomass harvesting.

Cysts can be processed locally, following the procedures described in Chapter II. During the first year of production simple air drying of cysts (as demonstrated at BBAP) can be applied. In the following years and when all brine reservoirs are operated for Artemia production the construction and use of a fluidized bed dryer or rotary dryer should be considered (drying capacity to be adjusted in function of total anticipated production estimated from the production of the 35 ha pond obtained in the first year.

v. Shutdown operation

At the beginning of the dry season when brine is drained back to the evaporation ponds as much biomass as possible is to be harvested by installing large bag nets (meshwidth of 800 μm or smaller with end part of < 50 μm to prevent extrusion of the animals) fixed to the drainage gates. The nets must be harvested at intervals of less than 1 hour as the Artemia accumulated at the end of the filtersac are exposed to anaerobic conditions.

4.4 POSSIBLE COOPERATION WITH RESEARCH SUB-CENTER IN GONDOL

The sub-center for Coastal Aquaculture Research in Gondol, Bali has nice pond facilities for studies in Artemia production but do not have adequate expert personnel. It would be ideal if some form of cooperation can be worked out between the sub-center and BBAP in Jepara. It is felt that such cooperation can promote a constant exchange of experience and results and will be mutually beneficial to the two institutions.

While the ponds have severe seepage and insect infestation problems, these are not insurmountable and techniques for correcting them are already established. Compaction of the pond bottom as practiced in Indonesian saltfarms and promoting the growth of algal mats on the pond bottom can gradually reduce the seepage. With continued usage, the faecal pellets produced by Artemia will further aid in the complete sealing of the pond bottom. Infestation by airborne insects can be avoided by simply using higher salinities (100 ppt). Once these are solved some of the studies that may be done at the sub-center are as follows:

• comparison of the effect of different types and varying rates of inorganic and organic fertilizers on the production yields of Artemia cysts and biomass;

• evaluation of the effect of salinity shocks on cyst production rate by abrupt lowering of salinity (e.g. from 150 to 120 ppt) through rapid intake of 30 ppt seawater (screened);

• comparison of the effect of different salinities (e.g. 180 vs. 100 ppt) on the biomass production and encystment rate of Artemia;

• comparison of different biomass harvesting rates in order to maintain the maximum sustainable yields, e.g. weekly harvesting of 10 vs. 20% of total standing crop of Artemia biomass.

Annex 1
ITINERARY AND PROGRAM

Annex 2
MATERIALS/EQUIPMENT FOR HARVESTING, PROCESSING AND QUALITY ANALYSIS OF CYSTS

a. Artemia Room (Jepara)

• aeration provided from a separate blower or branch from main blower. Use 2 inch PVC pipe as to ensure that sufficient quantities of air can be tapped
• fluorescent day light tubes
• plastic water bottles (cut off bottom) + support
• aeration lines tubes + valves
• small screens : 150, 350, 800 μm
• squeezing bottles
• petridishes
• measuring cylinders
• separatory funnel
• pipettes (0.5 ml, 5 ml)
• containers for storing filtered seawater, distilled water and saturated brine
• chemicals : NaOCl, NaOH, lugol's solution (KI, I₂, Na-acetate), H₂O₂ - store chemicals in refrigerator
• dissection microscope
• refrigerator, freezer
• etc.

b. Cyst Processing Room (Jepara and/or Sumenep, partly outside)

• freshwater supply
• container for storing saturated brine
• screens (800, 350, 150 μm) for size cleaning of cysts
• cylindroconical containers (preferentially transparant) for density separation of cysts
• cyst bag (150 μm screen) + domestic (clothes) centrifuge (optional)
• drying racks (150μm screen) + fan, or rotary dryer or fluidized bed dryer placed in a dry temperature controlled room
• plastic bags or cans (canning machine)
• N₂-both
• vacuum pump

c. Moisture Content Analysis

• analytical balance
• dessicator + silicagel
• drying oven (60 ° C)

d. Cyst/Biomass Harvesting (on site)

• nets/screens : 50, 150, 800 μm
• plastic sheet or corrugated plastic to line dikes

e. Limestone/Ammoniumsulphate, Tea Sead Cake (rotenon) for Pond Preparation

Annex 3.
Conversion table for various units of salinity.

(from Sorgeloos et al, 1986, Manual for the Culture and Use of Brine Shrimp Artemia in Aquaculture.)