Now showing items 1-20 of 29

    • Article

      Accumulation and excretion of metal granules in the prawn, Penaeus monodon, exposed to water-borne copper, lead, iron and calcium 

      G Vogt & ET Quinitio - Aquatic Toxicology, 1994 - Elsevier
      Juveniles of the giant tiger prawn, Penaeus monodon, were exposed for 10 days to 1 mg/l copper, lead, iron or calcium in order to investigate the formation and accumulation of metal granules in major soft tissues as well as their excretion from the body. Metal deposition was investigated by histochemistry and electron microscopy in the hepatopancreas and surrounding organs and tissues like the stomach, midgut, anterior midgut caecum, thoracal antennal gland extensions, haematopoietic tissue, and interspersed musculature, connective tissue and pigment tissue. The abundance of metal granules varied greatly between the metals and the tissues. Iron and calcium deposits were found in none of the tissues investigated. Copper granules were accumulated in high quantity in the hepatopancreas tubules, were scarce in the antechamber of the hepatopancreas, the anterior midgut and the anterior midgut caecum, and were lacking in the other tissues. The amount and size of copper granules increased along the hepatopancreas tubules in accordance with the cells' age. The granules were released by discharge of senescent hepatopancreas cells in the antechamber region and were added to the faeces. Lead granules were primarily found in the thoracal extensions of the antennal gland. In the hepatopancreas they occurred only in very small quantities, and in the other organs and tissues they were absent. In the antennal gland, the lead granules were individually discharged into the gland lumen by apocrine secretion and excreted with the urine. The observed ability of Penaeus monodon to detoxify and remove metals like copper and lead by granule formation and excretion and to prevent other metals like iron from entrance into major soft tissues corroborate that decapods are no suitable organisms for a long-term biomonitoring of heavy metal pollution.
    • 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

      Community-based technology transfer in rural aquaculture: The case of mudcrab Scylla serrata nursery in ponds in northern Samar, central Philippines 

      DB Baticados, RF Agbayani & ET Quinitio - AMBIO: A Journal of the Human Environment, 2014 - Springer Verlag
      Finding aquaculture development approaches to open up livelihood opportunities for the rural poor and in mainstreaming smallholder fish farmers to reduce poverty remain a challenge. This paper examines the community-based technology transfer mechanism of mudcrab nursery in ponds and its socioeconomic impacts on smallholder mudcrab growers in Northern Samar, Philippines. Results indicated that the technology is a viable enterprise done by a straight culture system method, which is the rearing of crablets from <1.0 to 4.0 cm for 42 days, or by-phases. However, technology adoption hinges on many factors like area ownership, farm distance from household, and market including the type of strategy needed to enhance technology uptake. Collaboration among research and development institutions and local partners is critical in training and empowering rural communities to adopt aquaculture technologies.
    • 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.
    • Article

      Culture of Scylla serrata megalops in brackishwater ponds 

      EM Rodriguez, ET Quinitio, FD Parado-Estepa & OM Millamena - Asian Fisheries Science, 2001 - Asian Fisheries Society
      Three- to five-day old hatchery-reared megalops (4.0 to 6.4 mg body weight) of the mud crab, Scylla serrata, were cultured to the juvenile stage in 20 m2 net cages installed in brackishwater nursery ponds. To establish a suitable stocking density, megalops were stocked at 10, 20, and 30 ind·m-2 in net cages. Treatments were replicated three times over time. After 30 days of culture, mean survival of juveniles ranged from 48.3 to 53.3% and did not vary significantly (P > 0.05) among the three stocking densities. Similarly, the mean final body weights of juveniles ranging from 2.91 to 3.40 g and mass weights 458.9 to 1066 g did not significantly differ among stocking densities. These results show that stocking of crab megalops directly in net cages in a brackishwater pond is feasible at any of the stocking densities tested.
    • Conference paper

      Development of practical diet for the grow-out culture of Scylla serrata in ponds 

      MR Catacutan, MF Mallare & ET Quinitio - In ET Quinitio, FDP Estepa, YC Thampi Sam Raj & A Mandal (Eds.), Proceedings of the International Seminar-Workshop on Mud Crab Aquaculture and Fisheries Management, 10-12 April 2013, Tamil Nadu, India, 2015 - Rajiv Gandhi Centre for Aquaculture (MPEDA)
      A series of feeding experiments were conducted in the laboratory and in ponds of SEAFDEC/AQD using hatchery-produced Scylla serrata juveniles to develop an effective pelleted grow-out diet. The practical feed ingredients included local and imported fishmeal, shrimp meal, copra meal, soybean meal, corn grits and squid liver powder. The other feed ingredients were rice bran, wheat pollard, bread flour and micronutrient mixes. The results in the laboratory trials were used to improve the feed composition for the culture of crab juveniles in grow-out ponds. Three runs (Run 1 - 108 days, Run 2 - 129 days and Run 3 - 114 days) were conducted in 270m2 ponds. Crab juveniles at stocking densities of 0.08 - 0.10m-2 were fed two dietary treatments containing 44% and 38% crude protein at similar dietary energy level estimated at 17 MJ/kg diet.

      There were no significant differences in the survival, growth and feed conversion ratio in each of the three runs. In Run 1, the survival rate of crabs fed with 44% protein was higher (56-77%) than crabs fed with 38% protein (35-50%), but these were not significantly different. In Run 2, < 5 g crabs could grow up to a mean body weight of 435 g with survival rates of 31- 45% after 129 days on a ration consisting of 80% pelleted formulated feed and 20% low value fish. Similarly in Run 3, a mean of 443 g was attained in less than 4 months with survival rates of 30-73%. The final average weight and specific growth rate of crabs fed these two diets were not significantly different which showed that in ponds, the 38% crude protein diet was able to sustain growth as with the 44% diet provided the dietary energy is similar. The feed conversion ratio for both test diets and low value fish showed a great variation (low value fish 1 to 4; test diets 1.81 to 5.6).

      This study showed that low value fish as the traditional feed for mud crab in the grow-out culture can be decreased to only 20% of the ration by incorporating 80% of formulated pelleted feed.
    • Conference paper

      Development of protocol for the production of hatchery-reared mud crab Scylla serrata juveniles for soft-shell crab farming 

      ET Quinitio, GX Libunao & 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
      Development of economically viable techniques for growing hatchery-reared juvenile crabs to suitable sizes will address the problem on the source of seed stocks for soft-shell crab farming. This paper reports the production of hatchery-reared mud crab Scylla serrata from juveniles in the nursery to 73-106 g body weight (BW) crabs in the grow-out pond for the individual system soft-shell crab farming. Likewise, the performance of hatchery-reared S. serrata, and wild S. tranquebarica and S. olivacea juveniles was determined in the soft-shell crab production set-up.

      The BW increased from 1.8-1.9 g to 78-113.7 g when stocked at 0.5 ind m-2 and from 1.6-2.3 g to 73-106.7 g at 1.0 ind m-2 after 75 days. Growth rates at both stocking densities were comparable. However, survival was significantly higher (P<0.05) in lower (63.6~c1.01%) than in higher (35.6~c3.34%) stocking density. Male S. serrata (46.0 ~c 1.75%) had significantly higher BW increase than females (39.4 ~c 2.05%). Crabs stocked at sizes of 51-60 g showed significantly greater percent increase in BW (43.26~c 0.98%) compared with those at 61-70 g (40.98~c1.33%), 71-80 g (38.55~c 1.04%), 81-90 g (36.34 ~c 1.27%) and 91-100 g (38.52 ~c 1.67%). Among the three species, hatchery-reared S. serrata (42.14 ~c 1.34%) had significantly higher mean percent BW increase compared with S. olivacea (38.23 ~c 0.49%) and S. tranquebarica (36.16 ~c 0.78%). S. serrata had significantly shorter mean culture period (24.11 ~c 0.95 days) than S. tranquebarica (28.48 ~c 0.54 days) and S. olivacea (28.75 ~c 0.34 days).
    • Book

      Diseases of juvenile and adult mud crab Scylla spp. in the Philippines 

      EA Tendencia, MVC Cabilitasan & E Tobias-Quinitio - 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 64
      This manual aims to provide updated information on the diseases of mud crabs initially authored by Lavilla-Pitogo and dela Peña (2004). It includes the name of the disease, causative agent, stages affected, effects on mud crab and methods of prevention and control. Except for the infectious diseases caused by viruses, which can be detected through molecular methods, most of the diseases can be visually diagnosed. Photographs of the external and internal anatomy of a normal mud crab, including the different sexes and species are included to help readers differentiate a normal from a diseased mud crab.
    • Conference paper

      The effect of different feed combinations using chicken egg yolk in Penaeus monodon larval rearing 

      E Quinitio & E Reyes - In GL Rogers, R Day & A Lim (Eds.), Proceedings of the First International Conference on Warm Water Aquaculture-Crustacea, held on the Brigham Young University Hawaii Campus, February 9-11, 1983, 1983 - Brigham Young University Hawaii Campus
    • Book chapter

      Fate and effects of water-borne heavy metals in Penaeus monodon 

      G Vogt & ET Quinitio - In N De Pauw & J Joyce (Eds.), Aquaculture and the environment: short communications and abstracts of contributions presented at the International Conference Aquaculture Europe '91, Dublin, Ireland, June 10-12, 1991, 1991 - European Aquaculture Society
      Heavy metals impair the aquaculture of shrimps and the quality of shrimp products. Some heavy metals occur in high amounts particularly in the hepatopancreas and the antennal gland (Gibson and Barker, 1979). This study was performed in order to determine whether copper, iron, and lead are accumulated in the hepatopancreas and the antennal gland extensions running along the hepatopancreas. Furthermore, damages of these metals and cadmium to the hepatopancreas cells were investigated. According to its commercial significance the giant tiger prawn, Penaeus monodon, was chosen as test species.
    • Conference poster

      Hepatopancreas cells as monitor cells for the nutritional value of prawn diets in aquaculture 

      G Vogt, FP Pascual & ET Quinitio - In Y Taki, J 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 hepatopancreas is considered to be the central organ of metabolism in decapod Crustacea. It is a system of blind tubules consisting of four cell types. The E-cells at the summits of the tubules develop into R-cells (for resorption of nutrients), F-cells (for production of digestive enzymes) and B-cells (function unknown).

      The ultrastructure of Penaeus monodon R-cells changes largely after starvation and feeding different diets. B-cells show slight reactions, while F- and E-cells are rather constant. Thirteen day-starvation results in a large decrease of the cell size and in a significant reduction of all cell organelles. After seven days starvation and four days refeeding with various extreme diets, the R-cells develop completely different food-specific ultrastructures. A distinct proliferation of the endoplasmic reticulum is characteristic of protein diets. Large fat drops are the main feature after refeeding with cod liver oil. Sucrose feeding results in "empty" cells with only few organelles. The most diversified ultrastructure with fat droplets and a high amount of all cell organelles is obtained by feeding a mixed diet.

      The study indicates that R-cells are very sensitive to the application of different diets. They could be used as monitor cells for the nutritional value and the availability of a diet for prawns. Particularly poor or badly formulated feed could be detected early by electron microscopy. This method may be very helpful for the development of artificial prawn diets in aquaculture, especially if natural sources will be used as food components.
    • Article

      Larval rearing of mud crab (Scylla): What lies ahead 

      K Waiho, H Fazhan, ET Quinitio, JC Baylon, Y Fujaya, G Azmie, Q Wu, X Shi, M Ikhwanuddin & H Ma - Aquaculture, 2018 - Elsevier
      The increasing global demand for mud crabs (genus Scylla) and threats to the wild populations highlight the urgency of fully rearing them in captivity. Despite considerable progress in mud crab production, most crab farms still rely heavily on wild-caught crablets and juveniles while the low and inconsistent success rates of larviculture remain as the main bottleneck impeding the development of mud crab aquaculture. Over the years, numerous studies have been conducted to determine the optimum larval rearing parameters, the ontogenic changes in digestive function and feeding behaviour, and the diets for different larval stages. These data, however, are dispersed and not summarised to inform culture practices. This review provides an update on the current progresses and to pinpoint the gaps in knowledge regarding mud crab larval rearing. We include all four mud crab species under the genus Scylla, i.e. Scylla serrata, Scylla olivacea, Scylla tranquebarica and Scylla paramamosain. Knowledge compiled in this review serves as an important guideline for prospective mud crab larviculture. Future research should gear towards filling in the gaps in our knowledge to advance mud crab larval rearing, thus fully incorporating mud crab into the aquaculture sector.
    • Article

      Leucaena leucocephala leaves in formulated feed for Penaeus monodon: a concrete example of the application of histology in nutrition research 

      G Vogt, ET Quinitio & FP Pascual - Aquaculture, 1986 - Elsevier
      Penaeus monodon postlarvae were fed with formulated diets containing either soaked or unsoaked Leucaena leaves. A similarly prepared feed with soybean in place of Leucaena was used for comparison. Results were analysed by statistical and histological methods.

      Results of the 4-week feeding experiment showed that mean weight gains and percentage survival of the prawns fed with the two Leucaena-containing diets were higher, but not significantly different from soybean-containing diet. The content of the poisonous amino acid mimosine in the Leucaena leaves could be reduced about 70% by soaking the leaves in freshwater for 24 h. Highest weight gain was obtained with the feed containing these soaked leaves.

      In addition to growth and survival, the R-cells of the midgut glands of the postlarvae were investigated by light and electron microscopy. Although the statistical growth values and the proximate analyses of the test diets were similar, a food-specific ultrastructure was established after only 4 days of feeding. All diets resulted in subcellular characteristics typical for well fed prawns and, at that time, the Leucaena diets were already slightly superior to the soybean control. This indicates that different sources of macronutrients lead to different ultrastructures even if the proximate analyses of protein, carbohydrate and lipid are similar.

      Only slight changes in the R-cells were observed after 11, 20 and 28 days in the prawns fed with the soybean diet compared to 4 days of feeding. In the diet containing unsoaked Leucaena leaves, however, many R-cells became heavily damaged after 20 and 28 days, whereas the prawns fed with the diet containing soaked leaves exhibited less pronounced distortion. Statistical analyses of growth and survival rate did not show these adverse effects at that time. Although it is highly probable that the mimosine is responsible for those pathological symptoms, complementary experiments could not clearly prove that.

      The effects of feed components are visible on the cellular or organ level after only a few days, whereas the individuals (organism level) reflect them about 10 days later. Another 10 days later the changes are manifested in the population. Therefore it is suggested to use histology in nutrition studies as a supplementary source of information to statistical and biochemical parameters. The midgut glands can further be used to monitor the nutritional condition of prawns in aquaculture, sea ranching, and in ecological investigations.

      The study confirms that Leucaena leaves are a promising protein source for prawn diets if mimosine could be reduced to a very low level. A mimosine level of 0.25% in the feed is still too high, if the diet is used uninterruptedly for several weeks.
    • Image

      Life cycle of mud crab 

      ET Quinitio - 2011 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Researched and conceptualized by Emilia T. Quinitio.
    • Article

      Lipids and fatty acids in wild and pond-reared mud crab Scylla serrata (Forsskål) during ovarian maturation and spawning 

      VR Alava, ET Quinitio, JB De Pedro, FMP Priolo, ZGA Orozco & M Wille - Aquaculture Research, 2007 - Wiley-Blackwell
      Wild-caught and pond-reared female mud crab Scylla serrata at different stages of ovarian maturation were collected from Samar and Capiz, Philippines. Crabs were categorized into five stages according to the external morphological and microscopic appearance of the most advanced oocytes. The ovaries, hepatopancreas, muscle and newly spawned eggs (NSE) were analysed for lipid class components and fatty acids. Total lipid was higher in pond-reared than in wild-caught crabs but increased with ovarian maturation in both groups. Ovarian lipid peaked at the fully mature stage, coinciding with a decline in hepatopancreatic and muscle lipids. Lipid levels declined significantly in spent females. The tissues contained elevated highly unsaturated fatty acids such as arachidonic (20:4n-6), eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3) acids, but at higher levels in late maturing and fully mature ovaries and in NSE. The type of lipid class and fatty acid components in mature ovaries as well as in NSE are generally considered to be indicative of their importance in reproductive physiology and embryonic and larval development.
    • Conference paper

      Mangrove structure and mud crab population in northern Samar 

      ET Quinitio, EB Vista, RC Vista & MJH Lebata-Ramos - 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
      This study assessed the mangrove community structure, relative seasonal abundance of all size classes of crabs (catch per unit effort or CPUE) and percent composition of the catch in two collection grounds in Pambujan and Rosario, Northern Samar using cylindrical bamboo traps and lift nets. Mangroves in Pambujan was dominated by Avicennia marina and A. alba. The initial total count of mangrove trees (67 stems ha-1) was slightly higher compared with the final count (61 stems ha-1). On the other hand, mangroves in Rosario was dominated by Rhizophora apiculata and R. stylosa. The total count of mangrove trees was higher in the initial (108 stems ha-1) compared with the final (46 stems ha-1). However, saplings and seedlings increased in both sites after 18 months. Mean CPUE ranged from 0.04 to 0.4 crabs using cylindrical bamboo traps in the monthly spring tide sampling for 19 months in Pambujan. High mean CPUE was recorded in February and August 2008. Mean CPUE ranged from 0.04 to 0.41 crabs using lift nets in the monthly spring tide sampling. The highest mean CPUE was noted in August. The initial and final CPUE were comparable. In Rosario, mean CPUE ranged from 0.3 to 1.78 crabs monthly caught in cylindrical bamboo traps and from 0.04 to 0.77 crabs in lift nets. In general, the number of crabs caught in both traps was higher in Rosario than in Pambujan. Mud crab ranged from 2.02-72.2% of the monthly total catch in lift nets in Pambujan. Other species of crabs ranging from 27.78 to 86.36% were the dominant catch in several months. In Rosario, mud crab ranged from 12.5 to 82.35% of the monthly total catch. The catch composition of the cylindrical bamboo traps was more varied compared with lift nets in both sites. The decrease in the population of mud crabs may also be associated with the decrease in mangrove trees. With the continuous cutting of trees and regular extraction of all sizes of mud crabs, the industry may no longer become sustainable. This paper is the first to be done on the assessment of the mud crab population in Northern Samar and the information gathered can be used as basis for the development and improvement of the existing fisheries legislation for the conservation and management of the remaining wild resources.
    • Conference paper

      Mud crab culture: challenges and opportunities 

      ET Quinitio & T Samraj - In SB Bhat, SK Thomas, A Muthuraman, SD Vincent & SPA Kumar (Eds.), Compendium of Proceedings of the Technical Sessions on Aquaculture and Ornamentals at INDAQUA - 2007, 11-13 January 2007, Chennai, 2008 - The Marine Products Export Development Authority
    • Conference paper

      Mud crab hatchery and grow-out status in the Philippines 

      ET Quinitio - In G Allan & D Fielder (Eds.), Mud crab aquaculture in Australia and Southeast Asia. Proceedings of the ACIAR Crab Aquaculture Scoping Study and Workshop 28–29 April 2003, Joondooburri Conference Centre, Bribie Island, 2004 - Australian Centre for International Agricultural Research
      Series: ACIAR Working Paper;No. 54
      Interest in mud crab aquaculture is increasing throughout the Philippines because of its demand both in local and export markets. Mud crab culture started as low-density polyculture with fish or shrimp using wild crab juveniles and developed to monoculture in ponds and cages. Recently, an integrated mangrove-crab culture system has been practiced. Mud crab species commonly cultured are Scylla serrata, S. tranquebarica, and S. olivacea.

      The yearly increase in production from 1996 to 2000 (Table 1) may indicate a corresponding increase in the seed collection activity due to greater demand of seeds for stocking. According to many gatherers in the country, there has been a declining volume of all size-classes, from juveniles to adult crabs, gathered from the wild over the last decade. Hence, the development of a commercially viable hatchery technology can play an important role in promoting sustainable crab aquaculture and fisheries management.
    • Book

      Mud crab nursery in ponds 

      ET Quinitio, E Rodriguez, RF Agbayani, B Juanga, D Baticados, M Catacutan & R Bombeo - 2010 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 47
      An extension manual that is highly illustrated, detailing the biology, nursery, harvest, marketing, costs-and-returns of mudcrab nursery in ponds.
    • Conference paper

      Mud crab nursery rearing practices 

      FD Parado-Estepa, ET Quinitio & EM Rodriguez - In ET Quinitio, FDP Estepa, YC Thampi Sam Raj & A Mandal (Eds.), Proceedings of the International Seminar-Workshop on Mud Crab Aquaculture and Fisheries Management, 10-12 April 2013, Tamil Nadu, India, 2015 - Rajiv Gandhi Centre for Aquaculture (MPEDA)
      The need for seeds for expansion of the mud crab industry led to the development of the hatchery technology. The nursery technology was developed as this served as a link between the hatchery, which produces megalopae or early crab instars, and the grow-out phase which requires bigger crab juveniles for a higher yield. The nursery has two phases, the first ending with production of crablets with 1- 1.5 cm carapace width (CW) and the second phase with crablets of 2.5-3.0 cm ICW. The more commonly recommended system employs stocking of megalopae or crab instars in net cages installed in ponds. Locally available unprocessed food and commercially available shrimp formulated diet are used for feeding. However, recent studies have successfully used formulated nursery diet for mud crab. One of the main problems in the nursery is cannibalism, and several strategies have been investigated and tried to address the problem.