Now showing items 10-29 of 79

    • 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.
    • Conference poster

      Effects of diet on reproductive performance of ablated Penaeus monodon broodstock. 

      OM Millamena, RA Pudadera & MR Catucatan - 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
      Four practical diets were compared for their effects upon ovarian maturation and spawning of ablated Penaeus monodon broodstock. Diets were formulated based upon the fatty acid profile of wild P. monodon. Diets 1 and 3 were cod liver oil-based while Diets 2 and 4 were soybean oil-based. Experimental treatments consisted of each of the formulated diets given in combination with natural food (squid, mussel, and annelids). An all-natural diet served as control. The fatty acid composition and total lipid content of the diets and of P. monodon fed with these diets were assessed.

      Reproductive performance was evaluated in terms of number of spawnings, fecundity, egg and nauplii production and hatching rate of eggs. Broodstock response was best in Diet 1 and comparable with the control, followed by Diets 3 and 4, and was poorest in Diet 2.

      Broodstock performance appeared to be related to the fatty acid pattern of the diet. All pelleted diets contained similar levels of total lipids. However, there were differences in amounts of important polyunsaturated fatty acids (PUFA): 20:4ω6 (arachidonic), 20:5ω3 (eicosapentaenoic) and 22:6ω3 (docosahexaenoic) acids. The fatty acid profiles of Diets 1 and 3 more closely resemble the profile of maturing ovaries of wild P. monodon; the PUFA content of these diets and ω3/ω6 ratios were higher compared to Diets 2 and 4. Diet 2, showing the poorest profile among the diets, was low in ω3/ω6 ratio and contained minimal levels of PUFA.
    • Oral presentation

      The effects of manures and pelleted feeds on survival, growth and yield of Penaeus stylirostris and Penaeus vannamei in Panama. 

      GI Garson, RM Pretto & DB Rouse - 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
      Brackishwater ponds (0.8 m deep and 600 m2) on the Pacific Coast of Panama were stocked at 5/m2 with post-larval shrimp (1 cm, 0.05 g) collected from the wild. Species composition at stocking was 56% Penaeus vannamei, 33% P. stylirostris and 11% P. occidentalis. Experimental treatments received different nutrient inputs consisting of cow manure (4,500 kg/ha dry wt.), chicken manure (4,500 kg/ha), 25% protein pelleted feed (790 kg/ha) and a control (no nutrient input), each replicated five times, in random order. Water was exchanged 5 to 10% per day and the production period was 120 days during the 1982 rainy season.
    • Conference poster

      Effects of some water-soluble vitamins on the growth 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
      The response of Penaeus monodon juveniles (ave. wt.= 0.076 g) in terms of survival and growth rates to vitamin test diets was observed in a 35-day feeding experiment. The prawns were reared in 60-ℓ oval tanks containing filtered seawater in a flowthrough system of ambient temperature and salinity. The treatments consisted of a control (complete vitamin mix), a vitamin-free diet and nine other diets, each lacking one of the vitamins in the mixture. At the end of the feeding trial, the survival rates in all treatments ranged from 80 to 100%, while weight gain ranged from 74 to 40%. Significantly lower weight gains were obtained from choline chloride-free diet (P<0.05) and vitamin-free and inositol-free diets (P<0.01) than from control.
    • Oral presentation

      The effects of stocking densities on growth and survival of Penaeus vannamei in cow manure-enriched ponds. 

      CS Lee, JN Sweeney & B Richards - 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
      Ecuadorian Penaeus vannamei were stocked in eight dirt ponds (approximately 163 m2) at four different types of density, i.e., 5 shrimp/m2, 10 shrimp/m2, 15 shrimp/m2, and 20 shrimp/m2. The initial body weight ranged between 1.1 and 3.8 g. No commercial feed was given to the shrimp. The only input to the pond was 30 kg of cow manure/week. Shrimp were sampled either weekly or bi-weekly for body weight measurements. Water quality parameters, such as temperature, pH, DO and turbidity were recorded twice daily; nutrients (nitrite, nitrate, ammonium and phosphate) and BOD were measured twice weekly. The chemical composition of the cow manure was analyzed. After 14 weeks' experiment, the shrimp were harvested, weighed and counted. Survival and total yield were compared among treatments.

      The results showed negative correlation between stocking density and growth. The weekly growth of shrimp was between 0.7 and 1.0 g. There was no relationship between stocking density and survival. Survival averaged 68%. The most suitable stocking density should be judged by profit. However, the total yield of shrimp was higher in the higher stocking density.
    • Conference poster

      Environmental physiology of the prawn Penaeus (melicertus) latisulcatus. 

      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 a number of intrinsic and extrinsic factors which affect the normal routine activity of the prawn. The present study attempts to elucidate the optimum levels of various environmental factors for the culture of prawns.

      The salinity tolerance capacity of Penaeus (Melicertus) latisulcatus was estimated in 13 different test salinities from 0 to 60 ppt (at 5 ppt increments). The prawns can tolerate a wide salinity range of 20-50 ppt. Maximum survival, however, was between 25 to 45 ppt. The extreme low (0-10 ppt) and high (60 ppt) salinities were highly lethal to the prawns. The change in acclimation temperature from 30 to 35°C increased the upper incipient lethal level from 38.5 to 39.5°C. The prawns acclimated to 30°C tolerated 42°C for 275 sec and 45.5°C for 13 sec, while prawns acclimated to 35°C tolerated 42°C for 505 sec and 46.5°C for 11 sec.

      Prawns were acclimated to a salinity of 26 ppt and oxygen consumption was measured at 5, 15, 26, and 38 ppt in a continuous water-flow method. The total oxygen consumption showed an inverse relationship with weight. Oxygen consumption declined with increase in salinity. The resistance of prawns to hydrogen sulphide was tested in 18 different concentrations of sodium sulphide mixed with seawater. The prawns tolerated sodium sulphide concentrations up to 20 mg/ℓ. The dissolved oxygen in the water was found to be reduced to very low levels with the increase in the concentration of sodium sulphide (from 5.9 ml O2/ℓ to 0.54 ml O2/ℓ). This may cause heavy mortality of the prawns.
    • Conference poster

      Evaluation of artificial feeds for shrimp (Penaeus monodon) production in brackishwater ponds. 

      NS Tabbu, P Kungvankij, G Taleon, I Potesta & M Bautista - 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 experiment was conducted in fifteen 500-m2 brackishwater ponds to determine the response of Penaeus monodon juveniles fed with various artificial diets. Five treatments with three replicates each were: two commercial feeds containing 45% and 40% crude protein (treatments I and II), two experimental diets formulated to contain 35% crude protein (treatments III and IV) and control, without feeding (treatment V). Shrimp were fed twice daily at feeding rates based on shrimp consumption.

      Highest mean harvest weight was attained in treatment I (23.47 g) > III (19.25 g) > II (18.86 g) > IV (11.29 g) > V (9.27 g). Statistical analysis showed that differences in growth were significant at 5% probability level. However, growth in treatments I, II and III are comparable, also growth in treatments II, III and IV. Growth in treatments I, II, III and IV was significantly different from treatment V. Highest mean survival was attained in treatment III (91.82%) > I (88.93%) > II (86.95%) > IV (83.62%) V (82.62%). Statistical analysis showed no significant differences among treatments at 5% probability level.

      Projecting on a hectare basis, mean yield for each treatment was: I (628.37 kg) > II (496.35 kg) per crop in 120 days culture. Good yield was attributed to provision of formulated feeds, use of pumps in addition to tidal change for water exchange and control of predators, and pest eradication through proper pond preparation.
    • Conference paper

      Extensive and semi-intensive culture of prawn and shrimp in the Philippines 

      FD Apud - 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
      Various farming systems for prawn and shrimp are compared, with emphasis on the extensive and semi-intensive culture of tiger prawn Penaeus monodon and white shrimp Penaeus indicus in monoculture or in polyculture with milkfish (Chanos chanos). The bases of comparison include pond design characteristics, stocking density, food supply, water management, average production, technical, and other major input requirements. Common factors that may influence production for each system are also discussed.

      It is observed that prawn and shrimp production has been mainly characterized by the extensive system. Of the 200,000 ha of brackishwater fishponds in the Philippines, about 25% (50,000 ha) are stocked with prawns and shrimps in monoculture or in polyculture with milkfish. Only a relatively small portion (less than 500 ha) of the area is utilized for semi-intensive culture. The dramatic increase in area utilization for extensive prawn production in recent years can be attributed to high market demand, increased hatchery-bred fry production, minimum technical requirements, and lower production cost and risks.

      The trend towards intensification among existing large fishfarms is hampered by rising capital costs for fishpond improvement and increasing operational expense and risks. However, intensification is gaining some attention and progress in limited areas, primarily to maximize utilization and production to avoid high investment cost of land for expansion. Further development and progress in the industry will be dependent on such factors as market price, availability of fry and feed at reasonable cost, supply of trained technicians, technical problems, financial situation, and economic viability of the operation.
    • Oral presentation

      Factors affecting maturation and spawning of Penaeus esculentus in the laboratory. 

      PJ Crocos - 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
      Adult tiger prawns Penaeus esculentus were held in laboratory tanks under varying conditions of tank size, density, temperature and photoperiod for assessment of ovarian maturation and spawning. Both eyestalk ablated and intact females were studied. Maturation and spawning of intact females was favored by conditions of warm temperature (26°C) and long days (14.5 hr), whereas ovary maturation did not occur at lower temperature (20°C) and short days (12 hr). Tank size was a critical factor with intact females as maturation and spawning required a large tank (4 m2). Spawning did not occur in small tanks (1 m2) despite ideal temperature and photoperiod conditions. Unilaterally ablated females matured and spawned under both short day-cold temperature conditions and in small tanks, but the success rate was greater under long day-warm temperature conditions in large tanks. Intact females required 40-60 days before onset of ovary maturation, whereas ablated females showed maturation to ovary stage III approximately 20 days after ablation. Mating success was severely limited under small tank conditions but occurred normally in the large tanks.