Now showing items 1-10 of 10

    • 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

      Identification and characterization of vitellin in a hermaphrodite shrimp, Pandalus kessleri 

      ET Quinitio, A Hara, K Yamauchi, T Mizushima & T Fuji - Comparative Biochemistry and Physiology - B: Comparative Biochemistry, 1989 - Elsevier
      1. A female specific protein (FSP, vitellogenin) in hemolymph and its related ovarian protein (vitellin) of Pandalus kessleri were studied by means of electrophoretical and immunological procedures.

      2. The vitellin was purified from vitellogenic ovaries using hydroxylapatite, DEAE cellulose and Sepharose 6B columns, consecutively.

      3. The vitellin had a molecular weight of approximately 560 kD and was composed of two subunits, 81 and 110 kD, respectively.

      4. The vitellogenin concentrations in the hemolymph increased as vitellogenesis in the ovarian oocytes advanced and dropped markedly after the release of mature eggs.
    • 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.
    • Conference paper

      Morphological deformities in mud crab Scylla serrata juveniles exposed to antibiotics during the larval stage 

      GS Pates Jr., ET Quinitio, GF Quinitio & FD Parado-Estepa - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The effects of antibiotics on the survival, growth and external deformities of mud crab Scylla serrata larvae and juveniles were determined. Zoeae were exposed to 0, 3, 6, 9, 12 mgL-1 oxytetracycline (OTC) and 0, 0.5, 1, 1.5, 2 mgL-1 furazolidone (furan) until the late megalopa in the first and second experiments. The treatments that gave the best results in the first and second experiments were conducted simultaneously in the third experiment. The surviving crab instar from each replicate were grown in nursery tanks for one month.

      Significantly higher survival and faster growth rate of Z5 were attained when 3 and 6 mgL-1 OTC or 0.5 and 1 mgL-1 furan were used. Morphological deformities observed in zoea 5 were bent dorsal, rostral and furcal spines. Percentage occurrence of morphological deformities was similar in all treatments. Significantly (P<0.05) higher survival and faster growth were attained among Z5 in the treatments using 3 mgL-1 OTC and 0.5 mL-1 furan in the third experiment. Morphological deformities observed in juveniles were fused frontal and lateral spines, asymmetrical and depressed tip of abdominal flap and gap between sternites. High percentage of deformities was observed in juveniles that were previously exposed to 6 mgL-1 OTC or 1.0 mgL-1 furan. There was no significant difference (P>0.05) observed in the survival of juveniles in both treatments of OTC and furan. However, growth was significantly (P<0.05) faster in lower concentrations of the two antibiotics.

      The study shows the apparent negative effects of antibiotics and highlights the need to eliminate or find alternatives, thereby preventing possible harm to the organisms and the environment.
    • Article

      Physiological and avoidance responses of juvenile mud crab Scylla serrata to mercury 

      HM Monteclaro, RP Babaran, RC Sanares & ET Quinitio - Aquaculture, Aquarium, Conservation and Legislation, 2014 - Bioflux
      The physiological and avoidance responses of juvenile mud crab Scylla serrata to mercury was evaluated by determining mortality using a renewal-type acute toxicity test and assessing crabs’ ability to avoid toxic concentrations. The 96-h LC50 of mercury to juvenile mud crab was computed to be 0.04 mg L-1. When transferred to clean waters, crabs that survived exposure to concentrations lower than 0.04 mg L-1 had better chances of surviving than those that were exposed to higher mercury concentrations. Avoidance of juvenile mud crabs to mercury was determined using a fluvarium, which provided the crabs a choice between untreated and Hg-treated waters. Results showed that juvenile crabs were not able to avoid waters that contain 0.1 mg L-1 mercury, a concentration that was more than twice the 96-h LC50 value. Juveniles previously pre-exposed in 1/50th of the 96-h LC50 value had a higher avoidance threshold and were not able to avoid waters with 1 mg L-1 mercury. Results suggest that juvenile mud crab is unable to avoid waters containing lethal levels of mercury and this may have potential impacts on crab biomass, distribution, growth, and development.
    • Conference publication | Book

      Proceedings of the Regional Technical Consultation on Stock Enhancement for Threatened Species of International Concern, Iloilo City, Philippines, 13-15 July 2005 

      JH Primavera, ET Quinitio & MR Eguia - 2006 - Aquaculture Department, Southeast Asian Fisheries Development Center
      This 150-page book documents the proceedings of an experts' consultation held at AQD in July 2005. It contains nine review papers and seven country papers.
    • Conference paper

      Reproductive performance of pond-sourced Scylla serrata fed various broodstock diets 

      OM Millamena & ET Quinitio - In Mud crab aquaculture and biology: proceedings of an international scientific forum held in Darwin, Australia, 21-24 April 1997, 1999 - Australian Centre for International Agricultural Research
      Feeding experiments were conducted to determine the effect of diet on reproduction of pond-sourced unablated and ablated Scylla serrrata broodstock. Broodstock were fed either natural food (T1) consisting of mussel, squid, fish by-catch, a combination of natural food and formulated diet (T2), or formulated diet (T3). After 120 days of culture, best broodstock response in terms of total spawnings, spawnings with hatchings, number of eggs per g body wt (BW) of female, egg fertilisation rate, and total zoea produced was obtained in T2 and poorest response was in T1. Broodstock in T3 gave intermediate values among the treatments. Larval quality measured as zoea growth index and broodstock survival was also highest in T2. Results showed that combination diet feeding improves the reproductive performance and larval quality of unablated and ablated females compared with those fed on natural food or artificial diet alone. Latency period from stocking to maturation and spawning was shorter in ablated than in unablated females. Rematurations were observed both in unablated and ablated females in all dietary treatments.
    • Article

      Runt-deformity syndrome in cultured giant tiger prawn Penaeus monodon 

      JH Primavera & ET Quinitio - Journal of Crustacean Biology, 2000 - Crustacean Society
      A total of 24 morphological abnormalities associated with the Runt-Deformity Syndrome (RDS) is reported for the first time in 17- to 18-mo old F3 generation Penaeus monodon (>40 mm CL) belonging to three breeding families. Although diagnosed as positive for the infectious hypodermal and hematopoietic necrosis virus (IHHNV), the shrimp appeared normal at 9 to 10 mo when they were procured from a commercial facility in Antique, central Philippines, in September 1996. The abnormalities affected either specific shrimp organs and appendages (e.g., rostrum, antennae, uropods) or the whole body (e.g., shell color and hardness). A two-way analysis of variance was used to evaluate differences in the morphometric characters rostral length (RL), carapace length (CL), abdominal length (AL), body length (BL), total length (TL), carapace width (CW), 1st abdominal segment width (AS1W), and body weight (BW) and the morphometric ratios RL:CL, CL:AL, and CW:AS1W by sex and stock (3 families and wild controls). Female P. monodon had significantly larger CL, AL, BL, TL, CW, and BW than males, regardless of stock. Wild females had longer BL and TL than cultured ones, whereas wild male shrimp had shorter CL, CW, and BW than cultured male P. monodon. Cultured shrimp had significantly higher CL:AL and CW:AS1W ratios and lower RL:CL ratio compared to wild P. monodon. The shorter and narrower abdomen relative to the carapace gave the shrimp a “runted” or dwarf appearance characteristic of RDS earlier described in Litopenaeus vannamei with IHHNV. Confirmed by parallel studies, IHHNV infection of the cultured P. monodon may account for their cuticular deformities, slower growth, and smaller sizes. The appearance of deformities in older (and bigger) P. monodon suggests that RDS expression is dependent on age and size. Examination for external abnormalities and evaluation of the three morphometric ratios may complement existing screening protocols for diseases and growth rates in shrimp breeding programs. Cultured giant tiger prawn also had lower sperm count, greater proportion of dead and abnormal sperm, and lower incidence of mating (absence of sperm in thelyca) compared to wild P. monodon.
    • Conference paper

      Updates on the seed production of mud crab 

      ET Quinitio, FD Parado-Estepa, JJ Huervana & MR Burlas - In MRR Romana-Eguia, FD Parado-Estepa, ND Salayo & MJH Lebata-Ramos (Eds.), Resource Enhancement and Sustainable Aquaculture Practices in Southeast Asia: Challenges in Responsible Production … International Workshop on Resource Enhancement and Sustainable Aquaculture Practices in Southeast Asia 2014 (RESA), 2015 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Widespread interest in mud crab species is increasing because these are highly prized both in domestic and export markets. Among the three mud crab species commonly found in the Philippines, Scylla serrata, S. olivacea, and S. tranquebarica, S. serrata is preferred by farmers because it is larger and less aggressive than the other species. Likewise, S. serrata is the most widely distributed species in the Indo-west Pacific region.

      Hatchery-produced seedstock are presently used by some crab farmers in their grow-out operations. In the hatchery phase, feeding mud crab larvae with shrimp formulated diets and natural food was found to reduce the occurrence of molt death syndrome, one of the major problems in seed production. Larvae given 25% formulated diet (FD) + 75% natural food (NF; rotifers and Artemia) and 50% FD + 50% NF showed better performance than those larvae fed 100% FD, 100% NF and 75% FD + 25% NF indicating that usage of natural food, especially the expensive Artemia, can be reduced. Since the early crab instar (C) produced in the hatchery need to be grown further before stocking in grow-out ponds, two phases of nursery culture have been developed. C1-2 are grown to 1.5-2.0 cm carapace width (CW) size in the first phase and further grown to 3.0-4.0 cm CW in the second phase. Nursery rearing is done in net cages installed in ponds for easy retrieval. A combination of mussel or trash fish and formulated diet is used as feed.

      Domestication of the mud crab S. serrata as a prerequisite to selective breeding has been done at SEAFDEC/AQD. Likewise, defining criteria for the determination of quality of newly hatched zoeae for stocking in the hatchery was initiated. Newly hatched zoeae were subjected to starvation and stress test using formalin. Starvation failed to elicit responses that were significantly different between the good and poor quality larvae hence it is not suitable for larval quality evaluation. Based on three-year data, the formalin stress test gave mean cumulative mortalities of 2.38±0.32, 8.24±0.88, 20±1.58 in good quality larvae, and 43.74±2.39 while 22.93±4.19, 63.68±7.17, 84.29±3.88 and 97.65±1.06 for poor quality larvae at 0 (control), 20, 30 and 40 ppm formalin, respectively. As formalin level increased, cumulative larval mortality also increased regardless of the quality of the larvae. Formalin stress test proved to be a reliable method to determine whether a batch of newly hatched zoeae was of good or poor quality.