Now showing items 1-20 of 34

    • Article

      Abdominal segment deformity syndrome (asds) and fused body segment deformity (fbsd) in cultured Penaeus indicus 

      The abdominal segment deformity disease (ASDD) is a new shrimp disease reported only in cultured Penaeus vannamei in Thailand. Shrimp with ASDD have deformed abdominal segment, jagged gut line and bumpy surfaces. Similar signs were observed in cultured P. indicus in the Philippines. However, aside from the signs described for ASDD, some P. indicus showing abdominal segment deformity syndrome (ASDS) had more severe deformities up to the extent that the number of body segments was reduced due to fusion. Shrimp with fused body segment deformity (FBSD) had four instead of five pairs of legs. To account the prevalence of the deformities in P. indicus, shrimp were classified into grossly normal shrimp (NS), shrimp with abdominal segment deformity syndrome (ASDS) and shrimp with fused segments (FBSD). Out of the shrimp sampled, 83.4 ± 5.4% was NS, 10.9 ± 6.2% was ASDS and 5.7 ± 3.0% was FBSD. Morphometric characteristics of the shrimp were measured. There was no significant difference in body weight (BW) among male and female NS, ASDS and FBSD. In both sexes, total length (TL) of FBSD was significantly shorter compared to NS and ASDS. Shrimp samples were also screened to be negative for known infectious viral diseases including white spot syndrome virus (WSSV), infectious hypodermal and haematopoietic necrosis virus (IHHNV), infectious myonecrosis virus (IMNV), P. vannamei nodavirus (PvNV), Macrobrachium rosenbergii nodavirus (MrNV) and Taura syndrome virus (TSV). Occurrence of ASDS and FBSD in post-larvae (PL) produced from captive and wild spawners were also determined. Based on a tank experiment, no significant difference was detected between the percentages of ASDS in PL produced from wild or captive spawners but FBSD was only noted in PL produced from the latter. Deformities generally did not affect the size of P. indicus except for the reduced length of shrimp with FBSD which when coupled with missing pleopods could lead to major economic loss for shrimp farmers if not addressed properly.
    • Article

      Acute hepatopancreatic necrosis disease (AHPND) outbreaks in Penaeus vannamei and P. monodon cultured in the Philippines 

      LD de la Peña, NAR Cabillon, DD Catedral, EC Amar, RC Usero, WD Monotilla, AT Calpe, DD Fernandez & CP Saloma - Diseases of Aquatic Organisms, 2015 - Inter Research
      Acute hepatopancreatic necrosis disease (AHPND) has recently emerged as a serious disease of cultured shrimp. It has also been described as early mortality syndrome (EMS) due to mass mortalities occurring within 20 to 30 d after stocking of ponds with postlarvae. Here, Penaeus vannamei and Penaeus monodon from shrimp farms in the Philippines were examined for the toxin-producing strain of Vibrio parahaemolyticus due to AHPND-like symptoms occurring in marketable size shrimp. In the P. vannamei, histology revealed typical AHPND pathology, such as sloughing of undifferentiated cells in the hepatopancreatic tubule epithelium. Analysis using the IQ2000 AHPND/EMS Toxin 1 PCR test generated 218 bp and 432 bp amplicons confirmative of the toxin-producing strain of V. parahaemolyticus among shrimp sampled from 8 of 9 ponds. In the P. monodon, histology revealed massive sloughing of undifferentiated cells of the hepatopancreatic tubule epithelium in the absence of basophilic bacterial cells. PCR testing generated the 2 amplicons confirmatory for AHPND among shrimp sampled from 5 of 7 ponds. This study confirms the presence of AHPND in P. vannamei and P. monodon farmed in the Philippines and suggests that the disease can also impact late-stage juvenile shrimp.
    • Article

      Acute toxicity of nitrite to mud crab Scylla serrata (Forsskål) larvae 

      ML Seneriches-Abiera, F Parado-Estepa & GA Gonzales - Aquaculture Research, 2007 - Blackwell Publishing
      Early larval stages of mud crab Scylla serrata were exposed to different concentrations of nitrite (40, 80 and 160 mg L−1 and a control, without added nitrite) and three salinity levels (25, 30 and 35 g L−1) using a static renewal method. No interactive effect of nitrite and salinity was detected. Estimated LT50 in 96-h toxicity tests decreased in all stages with increasing nitrite concentrations in all salinity levels. The 96-h LC50 values of nitrite-N were 41.58, 63.04, 25.54, 29.98 and 69.93 mg L−1 for zoea 1, 2, 3, 4 and 5 respectively. As the larvae grew, they showed a progressive increase in tolerance to nitrite. The toxicity of nitrite to larvae increased with exposure time. The median lethal concentration was not affected by salinity. The chloride component of salinity within 25–35 g L−1 did not seem to be as effective in alleviating toxicity as has been reported in other crustacean species. Based on 96-h LC50 and an application factor of 0.1, the ‘safe level’ of rearing mud crab larvae was calculated to be 4.16, 6.30, 2.55, 2.99 and 6.99 mg L−1 nitrite-N for zoea 1, 2, 3, 4 and 5 respectively.
    • Article

      Apparent digestibility coefficient of nutrients from shrimp, mussel, diatom and seaweed by juvenile Holothuria scabra Jaeger 

      ZGA Orozco, JG Sumbing, MJH Lebata-Ramos & S Watanabe - Aquaculture Research, 2014 - Wiley
      The ability of Holothuria scabra to digest nutrients, such as organic matter (OM), protein and carbohydrate from animal and plant feed ingredients was investigated. Four test feeds prepared by mixing sand with single ingredients from animal sources (shrimp and mussel) and plant sources (diatom and seaweed) were fed to H. scabra to estimate apparent digestibility coefficient (ADC). The total assimilated nutrient (TAN) increased with ADC, whereas ingestion rate (IR) varied slightly among the feeds suggesting that ADC might be a good indicator of nutrient availability to H. scabra. The ADCOM of shrimp and mussel was significantly higher than that diatom and seaweed: 86.2%, 77.1%, 55.1% and 32.3% respectively. ADCprotein was similar for shrimp (88.7%), mussel (84.8%) and diatom (75.2%), but significantly lower in seaweed (34.4%). ADCcarbohydrate was similar in mussel (58.5%) and diatom (58.3%) as well as in seaweed (31.6) and shrimp (28.0%). ADCprotein was relatively higher than ADCcarbohydrate suggesting that H. scabra generally digests more protein than carbohydrate. Furthermore, results indicated that nutrients from animal-based feeds are more efficiently digested by H. scabra; thus, animal ingredients rich in easily digestible protein could potentially provide an efficiently balanced diet for H. scabra fed with diatom containing high easily digestible carbohydrate.
    • Article

      Approaches to stock enhancement in mangrove-associated crab fisheries 

      L Le Vay, MJHL Lebata, M Walton, JH Primavera, ET Quinitio, CR Lavilla, FD Parado-Estepa, E Rodriguez, VN Ut, TT Nghia, P Sorgeloos & M Wille - Reviews in Fisheries Science, 2008 - Taylor & Francis
      Over the last decade, hatchery production of mud crabs has become technically and economically more feasible, enabling evaluation of the potential effectiveness of hatchery release in fisheries enhancement. The high growth rates and limited movement of released crabs means that fisheries’ yields an isolated mangrove systems with restricted recruitment can be enhanced with a few months. Thus, a release program may be an effective strategy for short-term enhancement in carefully selected specific areas. To date, results are very promising; with recovery rates up to 50% and increases in fisheries’ yield up to 46% over baseline catches. In contrast, mark-recapture studies in more open mangrove system populations shows that recruitment success and subsequent stock abundance may be largely determined by habitat availability. For these populations, restoration of lost o degraded mangrove areas has been show to be effective in promoting stock recovery through natural recruitment, with replanted mangroves supporting fisheries of equivalent economic value to that of natural mangroves, though it may take some years to reach these levels. Thus, a balanced approach to stock management could integrate both hatchery-release and habitat restoration programs, depending on local conditions and over different thin scales, with parallel-co-management to support effectiveness.
    • Article

      Artificial substratum consisting of poly-β-hydroxybutyrate-based biodegradable plastic improved the survival and overall performance of postlarval tiger shrimp Penaeus monodon 

      G Ludevese-Pascual, JL Laranja, E Amar, P Bossier & P De Schryver - Aquaculture Research, 2019 - Wiley
      The use of artificial substratum consisting of poly‐β‐hydroxybutyrate (PHB)‐based biodegradable plastic for penaeid shrimp culture was investigated in the present study. The survival of postlarval tiger shrimp Penaeus monodon (30 ± 5 mg) provided with PHB substratum made out of PHB type DP9002 (Metabolix GmbH, Köln, Germany) was 88.7 ± 3.4% and this was significantly higher as compared to postlarvae provided conventional substratum consisting of polyvinylchloride (PVC) pipes (67.3 ± 6.5%). However, no significant weight improvement was observed for the postlarval tiger shrimp indicating that PHB could not be used as growth promoter. Nevertheless, a trend of improved robustness against adverse environmental conditions (lethal ammonium chloride concentration) and increased resistance to pathogenic Vibrio was observed in postlarval tiger shrimp provided with PHB substratum as compared to postlarvae provided with PVC substratum. Results indicate higher preference by postlarvae on PHB substratum over PVC substratum. Overall, this study indicates the potential of artificial substratum consisting of PHB‐based biodegradable plastic as replacement for conventional substratum consisting of PVC pipes in enhancing the survival of postlarval tiger shrimp and improving its performance against adverse environmental conditions and disease resistance.
    • Article

      Comparative study on the embryonic development of three mud crabs Scylla spp. 

      MCD Ates, GF Quinitio, ET Quinitio & RC Sanares - Aquaculture Research, 2012 - Blackwell Publishing
      Morphological changes in the embryos, egg size and development, incubation period and morphological structures of newly hatched zoea of three mud crab Scylla species were determined. The three species exhibited similar embryonic development composed of 10 stages. The mean egg diameter of Scylla serrata was significantly larger (P<0.05) at the prehatch stage. The mean egg diameters of Scylla tranquebarica and Scylla olivacea were similar (P>0.05). The incubation period was the longest in S. serrata and the shortest in S. olivacea. There was a positive relationship between egg size and larval size, as S. serrata exhibited the largest egg size and first zoea. However, no correlation was detected between egg size at prehatch and lengths of the morphological structures of the newly hatched zoea. The three species exhibited similar lengths of cephalic structures, but S. olivacea had significantly shorter (P<0.05) abdominal structures. The duration of spawning from ablation was the shortest in S. tranquebarica and the longest in S. olivacea. The study is relevant to aquaculture and fisheries management of Scylla species.
    • Conference paper

      The decline of native fishes and fisheries and the rise of aquaculture in lakes and rivers in the Philippines 

      T Bagarinao - In Conservation and Ecological Management of Philippine Lakes in Relation to Fisheries and Aquaculture: Proceedings … Seminar-Workshop held on October 21-23, 1997, INNOTECH, Commonwealth Ave., Diliman, Quezon City, Philippines, 2001 - Aquaculture Department, Southeast Asian Fisheries Development Center; Philippine Council for Aquatic and Marine Research and Development (PCAMRD), Department of Science and Technology; Bureau of Fisheries and Aquatic Resources
      This paper reviews historical and recent data on biodiversity, fisheries, exotic fishes, and aquaculture in Philippine lakes and rivers. The country's lakes and rivers are poor in primary freshwater fishes because the Philippines' only connection with the Asian mainland had been through land bridges between Borneo, the Sulu islands, Mindanao, Palawan and Mindoro - in which islands endemic carps have evolved. Philippine lakes and rivers instead have secondary freshwater fishes such as gobies, migratory marine fishes such as mullets, and some snails, clams, and prawns. Most lakes and rivers have been severely degraded and their biodiversity reduced by siltation, pollution, overfishing, and the establishment of exotic fishes from other countries or elsewhere in the country. Many fishes first described in the Philippines in 1910-1940 by Seale, Herre, and Filipino ichthyologists have not been collected in recent years. The Laguna de Bay fishery in the early 1960s was largely dependent on the 'ayungin' Therapon plumbeus, 'biyang puti' Glossogobius giurus, and the 'kanduli' Arius manilensis that together comprised 95% of the annual 83,000 mt; another 19,000 mt came from shrimps and 245,000 mt from snails. Fishing and snail-dredging were so intense that catches declined and the whole lake fishery collapsed around 1970. After the collapse, the primary production of the lake increased and milkfish and tilapia became natural choices for aquaculture. Lake Lanao became famous for its species flock of 18 endemic carps, but these are now extinct, except perhaps two species. In 1963, these carps contributed 981 mt to the fishery, other native fishes 269 mt, shrimps and snails 257 mt, and introduced fishes 479 mt. Twenty years later, endemic carps have made up only 92 mt, native fishes 141 mt, shrimps and snails 164 mt, and introduced fishes 312 mt of the harvest from the lake. The 'kadurog' G. giurus, probably stocked in the lake with milkfish larvae in 1955, proliferated in the 1960s and apparently drove the endemic carps to extinction. The 'katolong' Hypseleotris agilis was first seen in the lake in 1977 and has since outcompeted the 'kadurog'. In Lakes Taal and Naujan, migratory marine fishes have been caught by fish corrals set across the outlets, but the catch along Pansipit River has fallen since the turn of the century and that in Butas River fell from 62 mt in 1977 to 17 mt in 1983. Catches of the endemic sardine Harengula tawilis in Lake Taal fluctuated between 4,400 mt in 1983 to 11,300 mt in 1990 and 1,400 mt in 1994. Cage culture of tilapia and milkfish has been going on in Lake Taal for 10 years. In Lakes Buhi and Bato, the endemic 'sinarapan' Mistichthys luzonensis almost disappeared due to fine-net fishing and tilapia stocking; catches have been 50-90 mt in 1983-93 but zero in 1994.
    • Article

      Domestication of the mud crab Scylla serrata 

      ET Quinitio, JJ de la Cruz, MRR Eguia, FD Parado-Estepa, GS Pates Jr. & CR Lavilla-Pitogo - Aquaculture International, 2011 - Springer Verlag
      The significant decrease in wild mud crab population highlights the need to manage the resources and domesticate crabs. This paper presents the initial results of the domestication of mud crab Scylla serrata aimed at producing good-quality captive broodstock. The analysis of the genetic structure of the base population was done as a prerequisite for domestication. Adult S. serrata from the northern to southern parts of the Philippines (Cagayan, Camarines, Samar, and Surigao) were obtained for genetic diversity analysis and domestication. Analysis of molecular variance showed that differences in the genetic variability between the four populations were not significant. Moreover, no significant deviation from Hardy–Weinberg Equilibrium was observed in each sample population and even in pooled populations. Body weight was positively correlated with the carapace width. Second spawning occurred 41–46 days after the first spawning and 34 days from second to third spawning. However, there was a decrease in the number of zoea in repeat spawnings. Twenty-four first-generation (F1) families were produced from the four sites. The duration from spawning of the base population (P0) to attainment of broodstock size F1 was 10–14 months. Four second-generation (F2) families were produced after 11–12 months. Up to the F2, crabs tested negative for six viruses: white spot syndrome virus, infectious hypodermal and hematopoietic necrosis virus, gill-associated virus, yellow head virus, Taura syndrome virus, and infectious myonecrosis virus. The reproductive performance of P0 was comparable to the succeeding generations. Several families were obtained from one population in a year. However, due to the cannibalistic behavior of crabs, more space is required for the nursery and grow-out phase. The domestication of S. serrata is the first study done on any mud crab species in the Indo-west Pacific region. The initial results would serve as guide to understand and eliminate the barriers to mud crab domestication. The breeding technology developed from this study will support the production of good-quality seedstock for farming.
    • Article

      Effect of salinity on hemolymph calcium concentration during the molt cycle of the prawn Penaeus monodon 

      FD Parado-Estepa, JM Ladja, EG de Jesus & RP Ferraris - Marine Biology, 1989 - Springer Verlag
      Prawns (Penaeus monodon) were obtained from ponds in Iloilo, Philippines, in 1984 and 1985 and maintained in salinities from 8 to 44‰. Total hemolymph calcium was largely affected by molt stage and less so by salinity. A sharp, transient increase in hemolymph calcium occurred 3 to 6 h postmolt, followed by an equally rapid decrease from 6 h postmolt to intermolt. This biphasis response was limited to prawns in 8, 20 and 32‰S; in 44‰S, hemolymph calcium remained the same throughout the sampling period. Peak concentrations of total calcium were greater in low (8 and 20‰S) than in high salinities. Salinity had no effect on the duration of molt cycle nor on time of occurrence of molt. Almost half of molting incidents occurred between 18.01 and 0.00 hrs, and one-third between 0.01 and 06.00 hrs.
    • Article

      Effects of dietary l-tryptophan on the agonistic behavior, growth and survival of juvenile mud crab Scylla serrata 

      JLQ Laranja Jr., ET Quinitio, MR Catacutan & RM Coloso - Aquaculture, 2010 - Elsevier
      The reduction of the survival of mud crab during culture has been largely attributed to aggressive encounters and cannibalism. In some crustaceans, suppressed aggression is linked to increased concentration of circulating and brain serotonin (5-hydroxytryptamine, 5-HT). Likewise, tryptophan (TRP), a precursor of 5-HT is reported to suppress the aggression and improve the survival of some cultured fish through dietary supplementation. We investigated the effects of feeding formulated diet with different TRP levels (0.32% as control, 0.5%, 0.75% and 1% of dry diet) on the agonistic behavior, growth and survival of juvenile mud crab Scylla serrata. Mud crabs were individually stocked and fed the experimental diets for 4 weeks before they were set to a one hour fight experiment. The fights were recorded using a video camera and the aggressiveness of the crabs was quantified. Hemolymph was sampled after 15 and 30 days of feeding (resting) and right after the fight to measure circulating 5-HT concentration. Higher TRP levels suppressed the aggressiveness of mud crab in a dose dependent manner. The intensity and frequency of attacks were both significantly lower (P < 0.05) in those given diets containing 0.75% and 1% TRP as compared with the control. Serotonin-ELISA assay revealed that 5-HT levels in the hemolymph before the fight (after 15 and 30 days; resting) were not significantly different between treatments. However after the fight, 5-HT concentration was significantly higher in TRP-supplemented mud crabs as compared with the control (0.5% = P < 0.05; 0.75% and 1% = P < 0.01). Furthermore, mud crabs (0.16 g BW) were reared in 0.40 m2 circular tanks at 20 crabs/tank and fed the experimental diets for 30 days to determine growth and survival. Survival was higher in TRP-supplemented mud crabs (0.5% = 35%, 0.75% = 33.33%, 1% = 35%) as compared with the control (18.33%). However, daily growth gain (DRG), relative growth rate (RGR) and specific growth rate (SGR) were reduced in TRP-supplemented groups than with the control group. In conclusion, the data shows that the aggressive behavior of juvenile mud crab can be suppressed by supplementation of L-TRP. The survival of juvenile mud crab can be improved by increasing the level of TRP to 0.5%–1%. However, higher TRP levels may affect growth of mud crab. TRP supplementation resulted to a significant increase of 5-HT concentration in the hemolymph which was clearly observed after the fight suggesting that 5-HT plays an important role in suppressing the agonistic behavior of mud crab during aggressive encounters.
    • Article

      Evaluation of hatchery-based enhancement of the mud crab, Scylla spp., fisheries in mangroves: comparison of species and release strategies 

      MJHL Lebata, L Le Vay, ME Walton, JB Biñas, ET Quinitio, EM Rodriguez & JH Primavera - Marine and Freshwater Research, 2009 - CSIRO Publishing
      Ranching, stock enhancement and restocking are management approaches involving the release of wild or hatchery-bred organisms to enhance, conserve or restore fisheries. The present study, conducted from April 2002 to November 2005, evaluated the effectiveness of releasing wild and hatchery-reared (HR) mud crabs in the mangroves of Ibajay, Aklan, Philippines where preliminary studies demonstrated declining fishery yields, abundance and size of crabs. Comparison of survival and growth of wild-released and HR Scylla olivacea and HR Scylla serrata demonstrated the effect of nursery conditioning, size-at-release and species differences. Overall yield and catch per unit effort (CPUE) increased by 46% after stock enhancement trials. Recapture rates of released crabs were highest in wild-released S. olivacea and in crabs measuring 65.0–69.9 mm carapace width (CW) and lowest in non-conditioned HR S. serrata. Growth rates were highest for conditioned HR S. olivacea and lowest for conditioned HR S. serrata (11.7 and 3.7 mm month-1 respectively). Fishing mortality was highest for S. olivacea, whereas natural mortality was greater for S. serrata. Conditioning hatchery-bred animals before release is also important in obtaining higher survival. S. olivacea was the more appropriate of the two species for release in mangrove habitats inundated with low-salinity water. However, there is a need for site-specific studies to evaluate the effectiveness of releases.
    • Article

      Extension of nursery culture of Scylla serrata (Forsskål) juveniles in net cages and ponds 

      EM Rodriguez, FD Parado-Estepa & ET Quinitio - Aquaculture Research, 2007 - Blackwell Publishing
      To address the preference of mud crab farmers for larger size Scylla serrata juveniles (5.0–10 g body weight or BW; 3.0–5.0 cm internal carapace width or ICW), a study was conducted to compare the growth and survival of crab juveniles (2.0–5.0 g BW; 1.0–3.0 cm ICW) produced a month after stocking of megalopae in net cages when reared further in net cages installed in earthen ponds or when stocked directly in earthen ponds. In a 3 × 2 factorial experiment, three stocking densities (1, 3 and 5 ind m−2), two types of rearing units (net cages or earthen pond) were used. Megalopae were grown to juvenile stage for 30 days in net cages set inside a 4000 m2 brackishwater pond and fed brown mussel (Modiolus metcalfei). Crab juveniles were then transferred to either net cages (mesh size of 1.0 mm) or earthen ponds at three stocking densities. After 1 month, no interaction between stocking density and rearing unit was detected so data were pooled for each stocking density and rearing unit. There were no significant differences in the growth or survival rate of crab juveniles across stocking density treatments. Regardless of stocking density, survival in net cages was higher (77.11±6.62%) than in ponds (40.41±3.59%). Growth, however, was significantly higher for crab juveniles reared in earthen ponds. The range of mean BW of 10.5–16.0 g and an ICW of 3.78–4.33 cm obtained are within the size range preferred by mud crab operators for stocking grow-out ponds.
    • Book

      Field guide for the edible crustacea of the Philippines 

      H Motoh - 1980 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Information on each species includes: 1) taxonomy (scientific, English and Philippine names) and diagnostic characters: 2) ecology; 3) distribution; 4) fisheries data; 5) economics (potential, price).
    • Article

      Formalin as an alternative to trifluralin as prophylaxis against fungal infection in mud crab Scylla serrata (Forsskål) larvae 

      JB de Pedro, ET Quinitio & FD Parado-Estepa - Aquaculture Research, 2007 - Blackwell Publishing
      The toxicity of formalin and trifluralin to the larval stages of the mud crab Scylla serrata was compared in a static bioassay. Prophylactic doses of 5, 10, 15, 20 and 25 μg L−1 formalin and 0.05, 0.1, 0.2, 0.4 and 0.8 μg L−1 trifluralin were used. Toxicity was assessed on the basis of survival of larvae after 24, 48, 72 and 96 h exposure to the test chemicals and metamorphosis to the next larval stage. Result shows that larval survival in all stages was significantly reduced at concentrations of 20 and 25 μg L−1 formalin whereas larvae were able to tolerate all trifluralin treatments. However, larvae became more tolerant to high formalin concentrations as the larval stage progressed. Survival was better at 5, 10 and 15 μg L−1 formalin and in all trifluralin treatments than the control in almost all the larval stages. Faster metamorphosis was observed at 5 and 10 μg L−1 formalin and 0.05, 0.1 and 0.2 μg L−1 trifluralin concentrations. Doses of formalin and trifluralin obtained from the toxicity experiments were applied as prophylaxis to newly hatched larvae in white plastic basins. Prophylactic doses of 5 and 10 μg L−1 formalin and 0.05 and 0.1 μg L−1 trifluralin applied every other day were found to be effective in enhancing survival and larval development to megalopa compared with control. However, no megalopae survived to crab instar in all formalin treatments. Although the use of fungicides in rearing systems resulted in higher survival compared with controls, other strategies (i.e. maintenance of good water quality and hygienic practices in the hatchery) should be further investigated as an alternative to the use of chemicals in hatcheries.
    • Article

      Identifying mangrove areas for fisheries enhancement; population assessment in a patchy habitat 

      MJH Lebata, ME Walton, JB Biñas, JH Primavera & L Le Vay - Aquatic Conservation: Marine and Freshwater Ecosystems, 2012 - Wiley
      1. Small-scale fisheries are an important element of the ecosystem goods and services that mangrove habitats provide, especially to poorer coastal communities that rely most on natural resources, and have similar values to payments for ecosystem services (PES) under carbon-trading schemes.
      2. In advance of fishery-enhancement trials for the mud crab Scylla olivacea, a mark–recapture study was conducted to estimate population size and turnover in 50 ha of isolated mangrove on Panay Island, Philippines. A total of 811 crabs were released in six sessions with an overall recapture rate of 41.5 ± 3.6%. Population size ranged from 607–1637 individuals.
      3. There was a high degree of site-fidelity, with 45.5% of recaptures in the same sampling areas as releases. Total mortality was 0.79 month-1, with fishing mortality accounting for 95% of overall mortality.
      4. Von Bertalanffy and Gompertz growth models yielded estimates for L (carapace width) of 117.3 ± 14.7 and 110.6 ± 2.1 mm and for k of 2.16 ± 0.74 and 3.25 ± 0.81, respectively. Crab densities of 12–33 individuals ha-1 in the study area were lower than in other mangrove systems owing to intermittent recruitment, while growth rates indicated no limitation in terms of food supply.
      5. The study demonstrates that in specific mangrove habitats that are below carrying capacity, there is potential for fisheries enhancement to sustain or increase direct economic benefits from mangrove ecosystems and hence promote community engagement in broader conservation and PES initiatives.
    • Article

      Induction of moulting in hatchery-reared mangrove crab Scylla serrata juveniles through temperature manipulation or autotomy 

      JJY de la Cruz-Huervana, ET Quinitio & VL Corre - Aquaculture Research, 2019 - Wiley
      The effects of temperature and autotomy of chelipeds on survival, growth and moulting of mangrove crab (Scylla serrata) juveniles were investigated under laboratory conditions for 60 days. Hatchery-produced crabs with 2.0?2.3 cm internal carapace width (1.7?2.2 g body weight) at intermoult stage were exposed to one of four temperature treatments (constant 29, 32 or 35°C, or ambient [24?31°C]) or subjected to cheliped autotomy. All crabs held at 35°C had 100% mortality due to incomplete moulting during first moult. The mean survival of crabs at termination was 58%, 64% and 50% for ambient temperature, 29 and 32°C respectively. Specific growth rate (SGR) of crabs in the ambient and 29°C were comparable but significantly lower than those at 32°C. The moult interval of the crabs was significantly shorter in treatments with constant water temperature of 29 and 32°C compared with ambient temperature. The survival of crabs with intact chelipeds was comparable with those with one or two autotomized chelipeds. Crabs with intact or one autotomized chelipeds had significantly higher SGR than crabs with both chelipeds autotomized in the first moult. On the second moult, however, high SGR was observed in crabs with two chelipeds autotomized. The moult interval was significantly shorter in the autotomized crabs compared with crabs with intact chelipeds. The results suggest that the optimum water temperature for rearing S. serrata juveniles ranges from 29 to 32°C. Likewise, autotomy of chelipeds can promote moulting without adversely affecting survival of crabs.
    • Conference paper

      Interaction of the midgut gland and the ovary in vitellogenesis and consequences for the breeding success: a comparison of unablated and ablated spawners of Penaeus monodon 

      G Vogt, ET Quinitio & FP Pascual - In N De Pauw, E Jaspers, H Ackefors & N Wilkins (Eds.), Aquaculture - A Biotechnology in Progress. Proceedings of the International Conference Aquaculture Europe '87, Amsterdam, The Netherlands, June 2-5, 1987, 1989 - European Aquaculture Society
      The midgut glands and ovaries of unablated and ablated females of Penaeus monodon were examined before and after spawning by light and electron microscopy to elucidate the role of the midgut gland during vitellogenesis. In addition, the larvae of both were divided into fed and starved groups and the mortalities were recorded up to stage postlarva 5 in order to compare the quality of the offspring from unablated and ablated spawners. Although a limited number of spawners was used in this preliminary study, a close interaction of the midgut gland and the ovary during vitellogenesis is evident. The influence of eyestalk ablation on the breeding success is discussed and hypothetically correlated to endocrinology. In late vitellogenesis, the resorptive cells of the midgut gland of an unablated female exhibited specific ultrastructural characteristics such as whirls of rough endoplasmic reticulum, conspicuous Golgi bodies and highly active smooth endoplasmic reticulum. The ablate these features only in moderate development. After spawning, the normal structures of the midgut gland cells were restored to a large extent. In the ovary of the unablated female before spawning, mature oocytes were dominant. After spawning, the ovary of the unablated female contained only immature oocytes. In contrast, all stages of maturation could be found in the ablated female 2h after spawning. The hatching rate was much lower in the ablated female. Up to stage postlarva 5, however, fed larvae from the ablated and unablated spawners had the same mortality rates. Starved zoea 1 from both types of spawners could not reach the next moulting stage without feeding. This indicates the urgent necessity of good feed at the very beginning of larval development. When the larvae were fed until moulting to mysis and then starved during mysis stage, the offspring of the ablated spawner died earlier than that of the unablated female. Only a very few starved larvae reached the postlarval stage. In any case, starvation led to an extension of the various larval stages and substages.
    • Article

      Isolation of Vibrio spp. from Penaeus monodon (Fabricius) with red disease syndrome 

      EV Alapide-Tendencia & LA Dureza - Aquaculture, 1997 - Elsevier
      From January 1990 to June 1993, 59% of the total juvenile to adult shrimp (Penaeus monodon) submitted for diagnosis at the Fish Health Section of the Aquaculture Department, Southeast Asian Fisheries Development Center, Tigbauan, Iloilo, Philippines were diagnosed to have red disease syndrome. Red disease syndrome is characterized by the reddening of the shrimp body. The aetiology of the disease is unknown. This paper reports for the first time the isolation of four Vibrio phenotypes, namely, Vibrio harveyi, V. parahaemolyticus, V. fluuialis and Vibrio sp. from shrimps with red disease. Pathogenicity test shows that injection with V. parahaemolyticus and V. harveyi can produce the characteristic red discoloration in healthy shrimp.