Now showing items 2-21 of 79

    • Conference paper

      Biology and ecology of Penaeus monodon. 

      H Motoh - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The giant tiger prawn, Penaeus monodon, the largest and most commercially important species among penaeids reaching 270 mm in body length or 260 g in weight, is suitable for culture in ponds and offers high market prices. This species occurs mainly in Southeast Asian waters, though it is quite widely distributed from 30°E to 155°E longitude and 35°N to 35°S latitude. Mating and spawning generally take place at night. The maximum number of eggs spawned at a time is more than 800,000. The life history is classified into six phases: embryo, larva, juvenile, adolescent, Subadult, and adult. The biological minimum size is 37 mm carapace length for males and 47 mm CL for females. The food consists mainly of small crustacea, mollusks and annelids. The adult is a predator of slow-moving benthic macroinvertebrates, or opportunistic in feeding behavior. This prawn is relatively eurythermal and euryhaline, growing rapidly to a large size. The life span may be one and a half to two years, and the female may live for a longer period than the male. In general, the female is larger than the male.
    • Conference poster

      The biology of Penaeus monodon in the capture fisheries off orissa coast, India in the context of occurrence of natural broodstock. 

      T Rajyalakshmi, SM Pillai & P Ravichandran - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The tiger prawn of India, Penaeus monodon Fabricius has a differential distribution in the two coasts of India. Density is high in the northeastern part of the Bay of Bengal gradually declining towards the mid-east and becoming quite scarce towards the south. On the west coast, the distribution is more sparse and limited to a few months, off Bombay. The only known inshore areas of capture fisheries are the Godavari estuarine system, and the lagoons off Orissa at Chilka and Madras at Pulicat. The only known offshore capture exists off the Orissa coast at Paradip and Puri extending south to Visakhapatnam and Kakinada Bay. The greatest production comes off the brackishwater "bheri" (wild culture) system in the extensive "sunderbans" of West Bengal on the northeast where millions of seed recruited to the Hooghly estuarine complex are drawn in along with tidal waters and "cultured." The distribution profoundly affects the maturity, breeding and recruitment of this highly euryhaline species.

      The distribution can be related to the cyclic currents in the Bay of Bengal which have a profound effect on the salinity and temperature profile. It can also be related to the immense quantity of freshwater inflow from the mighty Hooghly-Matlah-Roopnarayan Padma estuarine complex at the head of the Bay and the other major riverine estuaries on the mid-east coast viz., the Mahanadi, Godavari and Krishna. The pattern of circulation and estuarine flows is such that it might also positively influence the food distribution, both live and detrital, in this region.

      Ripe (gravid) and ripening females and males of P. monodon in the size range of 100-250 g are captured off Paradip coast in the not very deep (30-40 m) waters where coastal trawlers operate, from October through April corresponding to the post-monsoon stability in the water movement and the increasing salinity. This offers a good augury for setting up hatcheries in adjacent zones using naturally mature forms. Catch records from one major freezing plant are presented to indicate the density and distribution of the species at the Paradip-Puri coast.
    • Oral presentation

      Brackishwater shrimp culture in India and its impact on socio-economics. 

      SG Krishman - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Utilization of potential area for shrimp culture in the traditional system was very meager — just 1.8% of total estimated available area of 1.45 million ha. The traditional paddy and fish culture and paddy cum fish culture systems and the return on investment (ROI) are explained. To adopt intensive culture, there is adequate scientific information based on many successful achievements throughexperimental trials indicating body weight of 16.7 g in 45 days for P. indicus with more than 80% survival rate proving economic viability. Basic studies were also made to find out the seasonal seed availability in different regions. Shrimp production to the extent of 500-700 kg/ha was achieved in many demonstration ponds organized by the Marine Products Export Development Authority indicating commercial reality of shrimp culture in India. As vast potential areas are available, shrimp culture will minimize the present 75% idle capacity of the Indian seafood processing industry which is over-dependent on shrimp as its major product for export.

      Furthermore, adding more areas to culture has direct impact on the socio-economic status of the rural population. Three thousand self-employed people are now known to be directly engaged in seed collection. In addition, the shrimp farmer realizes returns two to three times more than his counterpart in paddy cultivation, in the same field and for more or less the same period of time. In West Bengal, of total export value of 43 crores, up to 25 crores is realized by farmers for their production of shrimp through culture reflecting better unit return for their raw material than that realized byprocessor/exporter of the end-product. Therefore, bringing additional areas under shrimp culture will directly affect the socio-economic status of the rural people employing an average of 5 persons/ha, and indirectly affect no less than 15,000 casual workers in the seafood processing industry by additional utilization of manpower and working hours.

      As productivity from capture appears bleak, brackish-water shrimp culture has been accorded top priority in India's national developmental programmes for more harvest from aquatic sources otherwise termed the "Blue Revolution."
    • Conference paper

      A brief review of the larval rearing techniques of penaeid prawns. 

      IC Liao - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      As early as half a century ago, Hudinaga successfully spawned and attempted to rear the larvae of Penaeus japonicus. Publications in the 1960 s, 70's and 80's on breakthroughs in larval rearing of one penaeid species after another indicated that practical prawn farming had become a reality. At present, there are 24 Penaeus species and seven Metapenaeus species whose larval rearing techniques are partially or fully established. Among them, only nine species are propagated on a large commercial scale. The other species are now produced only on a small scale or experimentally.

      There are many published papers dealing with larval rearing techniques of penaeid prawns. However, it is recognized that numerous details and problems remain unsolved pending further investigation and improvement. P. japonicus is the species which boasts the longest research history and the most successful larval rearing techniques. Nevertheless, there is little which scientists are able to do with the serious "white-turbid midgut gland disease" which has plagued the postlarvae of P. japonicus for the past several years. Similarly. P. monodon larval culture in the Philippines was once seriously affected by a fungus disease cause by Lagenidium sp., which resulted in poor survival rate.

      Suitable larval rearing methods differ from one species to another, all showing varying degrees of modification from the major principles of larval rearing techniques of penaeid prawns. For example, a hatchery can easily obtain several hundred spawners of P. japonicus, but this is never the case with P. monodon. Therefore, the community culture method for rearing larvae in large tanks is preferred for the former species, while the separate tank method, also called the monoculture method, is best for the latter.

      In general, larval rearing techniques of prawns is at its rapid growing stage. The status of larval rearing including rearing methods, feeding regimes and rearing systems, are herein summarized and introduced. The high priority problems to be solved, such as 1) selection of spawners, 2) improvement of rearing techniques, 3) larval diseases, 4) shipping methods, and 5) social impact are discussed and the prospects of larval rearing are described.
    • Conference poster

      Carbohydrate requirements of Penaeus monodon juveniles. 

      VR Alava & FP Pascual - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Penaeus monodon juveniles (initial mean weight=0.62 g) were fed semi-purified diets containing 10, 20 and 30% trehalose, sucrose or glucose for eight weeks. Results showed that shrimps fed 20% trehalose gave the highest growth rate. Of the three types of sugars tested, trehalose promoted the best growth rates, followed by sucrose and glucose. When the level of sugar was considered, 20% gave the best growth rate and 30%, the lowest. The type as well as level of sugar greatly affected the body crude protein and body lipid (P < 0.01), while survival was mainly affected by type of sugar alone (P < 0.01). Trehalose and sucrose diets promoted better survival than glucose diets. A negative linear correlation (r = —0.70) between the body crude protein and body lipid was obtained.
    • Oral presentation

      Cause of musty flavor in pond-cultured penaeid shrimp. 

      RT Lovell & EJ Livant - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      In 1983, penaeid shrimp shipped into the United States from culture ponds in Ecuador were found to have an intense earthy-musty flavor which made them unmarketable. High concentrations of geosmin (trans, 1-10-dimethyl-1-9 decalol), a musty odorous compound, were found in the tail muscle of the shrimp. The level of geosmin, 78 mg/kg muscle, was much higher than levels usually found in pond-cultured freshwater catfish of 13±3 mg/kg muscle. Cause of the rare occurrence of off-flavor in the shrimp is hypothesized to be severe reduction in salinity in the coastal culture ponds which allowed growth of odor-producing blue-green algae.
    • Conference poster

      Characterization of ovarian maturation stages in wild unablated Penaeus monodon. 

      JD Tan, RA Pudadera & EG De Jesus - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      At least five wild-caught Penaeus monodon from various maturation stages (initially classified in vivo as 0, I, II, III, IV, V) were measured, weighed and dissected for histological and histochemical studies. The anterior and posterior parts of the thoracic and abdominal regions of the ovary were sampled and stained with Mallory trichrome, alcian blue-periodic acid-Schiff (AB-PAS) and Sudan black.

      Results showed that the ovary is composed of the ovarian wall and its extensions, zone of proliferation, follicle cell layer and oocytes. The proliferating cells are less than 10 µm, have thin rims of cytoplasm, and increase in size as maturation proceeds. Based on histology, the stages were finally classified into groups (1) previtellogenic (stage 0), (2) vitellogenic (stages I and II), (3) cortical rod (stages III and IV), and (4) spent (stage V). The previtellogenic group consists only of perinucleolar oocytes (46-72 µm) which are stained negatively with AB-PAS and Sudan black. Oocytes bigger than 55 µm are enveloped by a single layer of follicle cells. The vitellogenic group is composed mostly of yolky oocytes (121-211 µm) with the following cytoplasmic inclusions: small granules of glycoproteins, medium-size globules of lipoglycoproteins, and few large lipid droplets. The cortical rod group consists mostly of yolky oocytes (288-408 µm) with additional rod-like bodies which contain acid and basic mucopolysaccharides but no lipid. The presence of cortical rods is a characteristic feature of mature penaeid ovaries. The spent group is similar to the previtellogenic group but contains some yolky oocytes, thicker follicle cell layers, or irregularly shaped perinucleolar oocytes. Th GSI ranges of the four groups are 0.899-1.937, 3.099-7.598, 5.631-12.000 and 1.848-2.919, respectively.
    • Oral presentation

      Culture of blue shrimp, Penaeus stylirostris in Sonora, Mexico. 

      JE Ramos & LR Martinez - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The Centro de Investigaciones Cientificas y Tecnologicas de la Universidad de Sonora has been conducting research on the culture of the blue shrimp Penaeus stylirostris since 1972. Most of the programs carried out are related to intensive culture in the Puerto Peñasco facilities. However, some experiments on semi-intensive and extensive culture have been conducted since 1975.

      This paper describes the principal aspects of the technology developed; spawners, larval culture, nursery, growth, feed, environmental parameters, water supply and others. While in intensive culture it is possible to attain over 5 kg shrimp/m2, in semi-intensive systems about 1 kg/m2 is obtained. The intensive system uses raceways for the grow-out of shrimp, the semi-intensive and extensive systems use ponds.
    • Oral presentation

      Description of the embryonic stages of Penaeus notialis and the influence of some abiotic factors on the species. 

      I Fernandez & M Oliva - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The embryonic development of the shrimp Penaeus notialis Farfante, 1967 is studied. The duration from spawning to hatching of the nauplii was 14-16 hr. As soon as spawning occurs, a sequence of transformations is observed in the characteristic cell mitosis up to the formation of the embryo which breaks the membrane and emerges as the first naupliar stage. The process of development is very similar to other penaeids and the duration of each stage is characteristic of the species. The influence of salinity and pH on spawning, hatching rate and survival, and the optimal values for each factor were determined.
    • Conference poster

      Diseases, parasites, commensals and fouling of commercial Penaeid prawns of the Portonovo coast of South India 

      A Ramasamy & AP Pandian - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      There are very few reports on the diseases, parasites, commensals and fouling in penaeid prawns. During the regular collection of marine and estuarine prawns in the east coast of India, a number were found to be infested with various organisms.

      The prawn Penaeus (Fenneropenaeus) indicus, was infested with a microsporidian which causes a condition known as milk or cotton prawn. The infestation was spread throughout the abdominal musculature of the prawn. The marine prawn Parapenaeopsis stylifera had epibiotic growth of athecate hydrozoans, probably of the genus Tubularia, on the dorsal side of the carapace and abdominal segments. This is the first report of athecate hydrozoans infesting the prawn. The prawn Metapenaeopsis stridulans was observed to be parasitized by a bopyrid isopod, Orbione thielemanni and the prawn Sicyonia lancifera, parasitized by another bopyrid isopod, O. kemi. The bopyrid isopod O. kemi infesting the prawn S. lancifera is also recorded for the first time. Both bopyrid isopods were found in the branchial cavity of the prawns. The Pontoniinid prawn Chernocaris placunae is a commensal living in the mantle cavity of the bivalve, Placenta placenta. Barnacles were found attached to the carapace and first abdominal segment of the prawn, Parapenaeopsis uncta, whereas they were found in the telson region also in the prawn P. stylifera. Most of the barnacles were very small with a basal diameter of less than 1.5 mm.
    • Conference poster

      Earthworm, marine annelids and squid as feed ingredients in formulated diets for juvenile Penaeus monodon. 

      FP Pascual - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Earthworm and annelids were incorporated in diets for Penaeus monodon juveniles (mean weight 0.54 g) either in wet or dry form. These protein sources were added in amounts needed to replace 10% of the animal source of protein. Other sources of protein in the diet were shrimp head meal, fish meal, and defatted soybean meal. Diets were computed such that two-thirds of total protein came from animal sources and one-third from vegetable sources. Other components of the diet were rice bran, sago palm starch, cod liver oil and a vitamin-mineral mixture. Another diet, used as maintenance diet, served as control. Postlarvae were randomly stocked at 6 individuals/tank in a flowthrough system with 5 replicates/treatment. Each of the oval fiberglass tanks had three 10-cm diameter PVC pipes for shelter. The prawns were fed 10% of biomass twice daily.

      Although treatment means for percent weight gain were not significantly different, the diet that contained dried earthworm or annelid meal gave higher weight gain than diets containing the wet form. The earthworm diet gave higher weight gain than diets containing annelids. Survival rate also followed a similar pattern as that of weight gain. Shrimp fed earthworm (wet or dried) gave survival rates numerically higher than those fed marine annelids. Shrimp fed the control diet had survival rates lower than those fed earthworm-containing diets but higher than those fed the wet annelid diet.

      In another experiment, earthworm or squid was incorporated in the diet. Survival rates of shrimp with earthworm or squid in the diet were significantly higher than those fed the control. Weight gains were not significantly different from each other. Food conversion was generally low. The drawback in the use of earthworm, annelids and squid is that they are relatively expensive compared to fish meal and shrimp head meal.
    • Conference paper

      An ecological approach to mariculture of shrimp: Shrimp ranching fisheries. 

      Y Uno - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Mariculture production in Japan has grown recently to nearly one million tons per year. Mariculture production in the shallow coastal waters of Japan mainly consists of eight species of finfish, six species of shellfish, and three species of algae.

      Kuruma shrimp culture techniques are highly developed. Nevertheless, only 1,800 tons of kuruma shrimp can be produced yearly. There is a demand for this species but culture grounds have become limited and there is not enough space to raise shrimp. In 1980, 600 million postlarvae were produced but one-half had to be released to the sea. The released shrimp that survived and grew have formed a new basis for the "Sea Ranching Fisheries" industry. The trial releases of postlarvae have proven that sea ranching of shrimp can be successful.

      To strengthen the foundation of sea ranching fisheries, there must be future research on ecological impact, as well as on physico-chemical water parameters. The life cycle, feeding habits, and predators of the shrimp must also be studied. Recent releases in Hamana-ko Lagoon, Shizuoka Prefecture, made by the research group of the Hamana-ko Substation of the Shizuoka Prefectural Fisheries Research Station have demonstrated the possibilities of sea ranching. This report discusses the research studies obtained at Hamana-ko Lagoon and the main problems of the use of this sea ranching method in mangrove swamp areas of Southeast Asia.
    • Oral presentation

      The economics of different prawn and shrimp pond culture systems: A comparative analysis 

      D Israel, F Apud & N Franco - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The paper aims to present a comparative economic evaluation of different pond culture systems for prawn (Penaeus monodon) and shrimp (P. indicus and P. merguiensis) using standard economic tools and methods of analysis. The different culture systems include extensive and semi-intensive monoculture of prawns and shrimps and the extensive polyculture of these species with milkfish (Chanos chanos). Data used in the analysis were taken from both SEAFDEC AQD and industry experience. The technical data were gathered from researchers and private sector experiences in prawn and shrimp farming. Financial estimates were determined after the peculiarities of aquaculture vis-a-vis other business ventures in agriculture and industry were taken into consideration.

      The study shows that the extensive monoculture of prawns and the extensive polyculture of prawn with shrimp and milkfish are profitable culture systems. Return on investment (ROI) and payback period for prawn extensive monoculture systems range from 10 to 65% and from 1.4 to 8.6 years, respectively. For polyculture systems, ROI ranges from 8 to 85% and payback period from 1.1 to 10.5 years. The semi-intensive culture of prawn shows moderate results. This is largely due to higher capital requirements for semi-intensive culture as compared to extensive culture. The extensive and semi-intensive monoculture of shrimps on the other hand show poor results, with semi-intensive monoculture registering net losses after all costs are considered.
    • Conference paper

      Economics of penaeid culture in the Americas. 

      W Griffin, A Lawrence & M Johns - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Shrimp culture in the Americas began in the early 1970's and has experienced rapid growth in some Latin American countries. Currently, Latin America produces one-third of all cultured shrimp with Ecuador as the leading country in the world. Availability of postlarvae and a favorable year-round climate have been the most important factors causing a "Gold Rush" expansion in Ecuador. The long-term potential for shrimp mariculture in Latin America is promising. Projections for 1990 production of cultured shrimp by Latin American countries are between 60,000-70,000 metric tons (mt). Shrimp culture in the United States has begun with the entry of a few small firms.

      In this paper, investment and production costs are examined for a semi-intensive farm that purchases postlarvae and operates in the southern United States. Total investment decreases as pond size increases for a given size facility. Investment per kilogram of annual average production ranges from just under US $20.00 for a 20-surface ha farm using 2-ha ponds to $80.00 for a 400-ha system using 20-ha ponds. Operation costs per kilogram decline as the size of the system and the size of the ponds increase. It costs $10.10 to produce one kilogram of shrimp on a 20-surface ha farm using 2-ha ponds compared to $5.50 on a 400-surface ha farm using 20-ha ponds.

      In comparing the operation of a semi-intensive 200-ha farm in Ecuador with a similar farm in the United States, costs of production were $3.12 and $5.83 per kilogram, respectively. The after-tax internal rate of return (IRR) was 59% in Ecuador and 21% in the United States. These IRR's were calculated under the assumption that production, costs and prices received are constant over the investment period (10 years) considered. When risk and timing of investment are considered, these IRR's are reduced.
    • Conference paper

      Economics of shrimp culture in Asia. 

      Y Hirasawa - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      There is a common belief that the demand for shrimp is so strong that the future of shrimp culture is very bright. However, there is a problem here. The Japanese market for shrimp has been expanding over the past 20 years, and the amount of imported shrimp has reached its ceiling. Since 1980, the amount imported has been 160,000 tons with some allowance. It will be rather difficult to exceed this level with the present price. It is very clear that if imports of shrimp rise above this level, inventory will rapidly increase and price will go down severely. Considering this situation, it is very important to reduce the cost of cultured shrimp because of severe competition in the market.

      Various shrimp culture systems in Japan and Southeast Asia are described. They range from extensive to intensive systems. An analysis of their economics reveals some interesting facts. The downward trend of the rate of cost per kilogram in intensive culture is very slow compared to those in extensive and semi-intensive culture while the productivity is rising. This is because in intensive pond culture, the ratio of variable cost to total cost is rather high and variable cost does not change as the productivity rises. In the case of extensive pond culture, the ratio of fixed cost to total cost is rather high, so the decrease in fixed cost per kilogram is very high in accordance with the rise of productivity. Therefore, by simply increasing the productivity slightly, the extensive pond can cut its production cost significantly. If the price of shrimp in the market goes down, the intensive pond system will face extinction since it is difficult to cut production cost.

      Cost forecast for cultured shrimp seems to indicate that extensive and semi-intensive methods will become dominant in the Asian region. Presently, productivity of these systems are low but can be greatly improved by using the "continuing method" and "circulating method" of pond management. The continuing method calls for stocking of different-sized shrimp which will be harvested on a staggered basis. The circulating method employs various sizes of compartments and the stock is moved from densely stocked small compartments to progressively larger grow-out ponds.

      There has been a rapid expansion of tiger shrimp culture in Taiwan and Southeast Asia recently for the following reasons: (1) high growth rate; (2) high price and broad market; (3) development of technology for hatching and rearing of seedling; and (4) comparative ease with which technical help in culture is obtained from Taiwan and Japan. However, there is a significant demerit. It is not easy in some regions to obtain seedling due to their high price. The supply of seedling of tiger shrimp is absolutely insufficient because of the shortage of mature shrimp. On the other hand, it is easy to get white shrimp seedling at a low price in these regions. In addition to this, the growth rate of white shrimp is similar up to a body length of 12-13 cm in 80-90 days rearing. Cheap cost and a large supply of seedling will easily compensate for the small size. It is therefore important to expand white shrimp culture in Asia. The bright future of white shrimp due to its low production cost is presented in this paper with some data and calculations.
    • Conference poster

      Effect of carrageenan micro-binded diet on the larval stages of Penaeus indicus. 

      Y Yashiro, M Bautista & E Daza - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      At present, most hatcheries depend on live food like diatoms, Chlorella, rotifer and brine shrimp to rear the larval stages of various penaeid species. Mass production of live feed requires much space (tanks) and labor, and is often affected by environmental conditions. The possibility of substituting live food with artificial diet for Penaeus indicus larvae was evaluated. Carrageenan micro-binded diet (C-MBD) was selected as test diet and its composition was modified from C-MBD designed for P. japonicus (about 45% protein).

      Larvae stocked at 100/ℓ and fed five times/day at 0.8 mg/larva/day had an average survival rate of 45% from Z1 to M1. Water temperature was 26.5-30.5°C and salinity 32-33 ppt. An average survival rate of 70.2% from M1 to PL1 was attained when the stocking density was 30/ℓ and feeding was three times/day at 0.3 mg/larva/day (water temperature 25.5-28.5°C, salinity 27-32 ppt). From PL1 to PL5 at stocking density of 20/ℓ with feeding rate of 0.3 mg/larva/day (fed 3 times a day), the average survival rate was 64.9% (water temperature 25.5-28.5% C, salinity 28-32 ppt).

      The results show that the present composition of C-MBD is highly effective for myses up to the early postlarval stages of P. indicus.
    • Conference poster

      Effect of cholesterol in artificial diets for Mediterranean prawns. 

      ML Bianchini - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Mediterranean prawn (Penaeus kerathurus Forsskal) postlarvae (2 months old) were fed ad libitum with previously tested artificial diet (41% D.W., mainly of vegetal origin) supplemented with different percentages of cholesterol (0, 0.1, 0.5, 1.0 and 3.0%) and fresh bivalve mussel. Growth and survival rates were determined twice.

      Considering supplemented formulas only, data show that: (a) individual weights were higher with 0.1% cholesterol in the diet; (b) survival sharply dropped in the last week of the experiment, in particular with 0.1 and 3.0% cholesterol diets; and (c) with 1.0% cholesterol, mortality and growth counterbalanced giving over-all better results.

      No artificial feed can compete with the natural diet, either for survival rate or for individual growth.
    • Conference poster

      Effect of dietary fatty acids on the fatty acid composition of Penaeus monodon juveniles. 

      M Catacutan & A Kanazawa - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Six purified diets containing either pollack liver oil or a combination of dietary fatty acids (18:1ω9, 18:3ω3, 20:5ω3) at 5% level and a control (no lipid) were assessed for their influence on the fatty acid composition of Penaeus monodon juveniles (0.2-0.5 g). After a 35-day feeding period, the fatty acid composition of the neutral lipid (NL) and polar lipid (PL) fractions of prawn total lipids was analyzed. All treatments showed that the prawn lipid contained high level of polyenoic acids (20:4ω6, 20:5ω3, 22:6ω3); likewise the sum of ω3 series fatty acids were high in the PL fraction. The component fatty acids of prawns showed a correlation with those of the diet. However, some dietary fatty acids were incorporated more into the NL fraction (18:1ω9, 20:5ω3) than in the PL fraction (20:4ω6). The ratios of 18:1ω9/22:6ω3 and (18:1ω9 + 20:1ω9)/(20:5ω3 + 22:6ω3) were found to be the lowest in the PL of the prawn pollack liver oil.
    • Conference poster

      Effect of temperature and salinity on the hatching of eggs and larval development of sugpo, Penaeus monodon. 

      EP Reyes - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Incubation of Penaeus monodon eggs and rearing of different larval stages were undertaken at nine temperature-salinity combinations. The eggs, nauplii, zoea and mysis from one spawner kept as stock culture at ambient temperatures of 26-30°C and salinity of 32-33 ppt were exposed to temperature levels of 23, 28 and 33°C and salinity levels of 23, 28 and 33 ppt.

      Eggs and nauplii survived the sudden change of temperature and salinity (from ambient to experimental) but the zoea and mysis did not. However, salinities of 23 and 28 ppt in combination with any of the temperature levels produced weak larvae. Highest mean hatching rate was obtained at the temperature-salinity combination of 23°C-33 ppt, followed by 28°C-33 ppt and 33°C-33 ppt. Incubation periods for these treatments were 22, 16 and 14 hr, respectively. Survival rate of nauplius (taken from stock cultures) to first zoeal stage was highest at 28°C-33 ppt, followed by 33°C-33 ppt and 23°C-33 ppt with molting time of 50, 45 and 75 hr, respectively.

      The nauplii exposed to 33°C-33 ppt molted to zoea stage within 38 to 40 hr but later died. Those exposed to 23°C-33 ppt and 28°C-33 ppt reached zoea stage within 57 to 60 hr and 48 to 50 hr, respectively. Similarly, the nauplii taken from the stock cultures and reared until postlarval stage (P1) under experimental conditions completed the zoea and mysis stages in 9 to 11 days at 28°C C-33 ppt, 7 to 9 days at 33°C-33 ppt, and 13 to 15 days at 23°C-33 ppt.

      Statistical analysis showed that salinity had highly significant effect on rates of hatching of eggs and survival from nauplius to first zoeal stage but not temperature although the latter had an apparent effect. However, both factors affected time of hatching of eggs and time of molting from nauplius to zoea. Interaction effect was significant only on rate and time of hatching. Different sources (spawners) of eggs and nauplii did not have significant effect on time of hatching and molting from nauplius to zoea, but significantly affected the hatching rate of eggs and survival rate of nauplii to zoea stage.
    • Oral presentation

      Effect of various levels of squid protein on growth and some biochemical parameters of Penaeus japonicus juveniles. 

      LC Suarez, J Guillaume & AV Wormhoudt - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      An unknown growth factor previously suspected in squid meal was found in the protein fraction of squid (Loligo vulgaris). It is clearly different from hydro-alcohol-soluble feed attractants that are also present in squid meal. This squid protein fraction (SPF) improves the growth of Penaeus japonicus juveniles when added either in a semi-purified or in a more complex mixed diet. This growth-promoting effect does not seem to be related to the amino acid composition of SPF. In order to obtain more information on its action, several levels (1.5 to 16.0%) of SPF were added to a mixed diet. The diets were isoproteic (59% D.M.), isolipidic (8.5% D.M.), supplemented with vitamins, cholesterol, glucosamine, etc. They were fed as wet pellets to 3 replicates of 15 shrimp; blue mussel was used as the control. The growth of shrimp increased with the SPF level and attained a plateau above 6%. Body weight was significantly higher than that of the control group at this level. RNA content and RNA:DNA ratio increased with the SPF level indicating that growth was improved more by hypertrophy than by hyperplasy of the cells.

      The hepatosomatic ratio remained unchanged. The assay of two digestive enzymes, proteases and amylases, showed no clear effect of SPF on protease or amylase activities. More experiments are needed to explain the effect of the unknown growth factor of SPF.