Farming freshwater prawns

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ANNEX 8 FIGURE1In Macrobrachium rosenbergii ponds which have not yet been harvestedin any way, there are two length frequency peaks for males (the smallerones sometimes being referred to as ‘runts’ and the larger ones as ‘bulls’)but only one peak for femalesSOURCE: FUJIMURA AND OKAMOTO (1972), REPRODUCED FROM NEW AND VALENTI (2000) WITH PERMISSION FROM BLACKWELL SCIENCEdifferences in moult frequency. SM have relatively large testes that both produce and storesperm. The testes of BC serve mainly as a sperm reservoirs. The three orange claw maleforms (WOC, SOC and TOC) represent a series of gradual changes between SM and BC.Firstly, the abundance of mature sperm found in the testes of SM declines and almost disappearsin the early OC stages. At the same time, the rate of production of spermatocytes(cells from which spermatozoa arise) increases as the SM moults into the OC phase. TheOC phase is also characterized by frequent moulting. Another differential feature is thesize (weight) of the midgut glands, especially the hepatopancreas. The hepatopancreasweight of the rapidly growing SOC is much greater than in all other morphotypes. Theslow-growing SM and BC have the lowest relative midgut gland weight, while the WOCand the TOC males have intermediate values.ANNEX 8, Figure 2The major malemorphotypes ofMacrobrachiumrosenbergii arecalled blue claw(BC), orange claw(OC), and smallmale (SM) (Israel)SOURCE: ASSAF BARKI, REPRODUCED FROM NEW AND VALENTI (2000) WITH PERMISSION FROM BLACKWELL SCIENCEFRESHWATER PRAWNS178
2. BehaviourThe behavioural characteristics of the morphotypes described above are of essential importancein the management of freshwater prawn grow-out facilities. BC males are aggressive,dominant and ‘territorial’, OC males are aggressive, subdominant and ‘non-territorial’, andSM males are submissive and ‘non-territorial’.FIGHTING (AGONISTIC) BEHAVIOURThe fighting behaviour of the three male morphotypes differs as males follow the developmentalpathway from SM through OC to BC. There is less physical contact and fewer displaysof claw position and movement occur in SM than in OC and BC. As claw size increasesthere is an increased risk of severe injuries caused by claws during interactions amongstOC and BC prawns. Male prawns have a hierarchical relationship. BC males are dominantover OC males which, in turn, are dominant over SM. Interactions between BC males areoften only for show, with little physical contact. Those between BC and OC males involvemore physical contact but BC males generally use threat displays and mere approaches intheir relationships with SM. BC and OC males with equal claw size are evenly matchedbut a BC with larger claws than an OC, even if the OC is much larger, has an advantage.The dominance of BC over OC seems to confer priority of access to preferred areas (e.g.shaded protected crevices) but true territoriality (defending a fixed exclusive area to keepintruders out) has not yet been adequately demonstrated. However, laboratory studieshave shown that competitors are evicted from the vicinity of a limiting resource, such asshelter, food, and receptive females.MATING BEHAVIOURFemales approach males 2 to 3 days before their pre-mating moult. At first the female ischased away but later, after several hours of persistence, is allowed to remain near the male.About a day before the pre-mating moult the female is already totally accepted by the male,positioned below it or between its long second pair of claws. As a result of this early pairbonding, fertilisation can occur from several minutes to half an hour after moulting. It hasbeen reported to occur up to nearly 22 hours later than the moult but this has been becauseresearchers were pairing the males and females themselves, rather than allowing the naturalbonding described above to occur. All three male morphotypes have similarly high ratesof fertilising receptive females. Despite the fact that the spermatophores of SM are abouthalf the size of those of BC males, the number of viable embryos following mating is dependentonly on the female size, not on the type of male morphotype.Males do not attack or injure the females that they have just fertilized. BC tend toguard the female for two or three days following mating, by which time the female’sexoskeleton is hard enough to withstand attacks by other prawns. However, OC do notappear to groom or protect the females. There are reports of injuries inflicted by OC onfemales during this period (especially when more than one OC is present) but the informationis, at present, conflicting. Small males have been observed to mate with females bysneaking between a receptive female and her guarding BC male. A single SM has little orno chance to gain access to a receptive female guarded by a BC male. However, SM matingcan be achieved when there are three or more SM present; while the BC is chasing awaysome of the runts, the female remains unprotected. Occasionally, following their pre-matingmoult, females have been observed with several spermatophores attached to theirsperm receptacle. There is some evidence that females are more attracted (throughANNEX 8179
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Farming freshwater prawnsA manual f
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The designations employed and the p
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abstractTHE ORIGINAL MANUAL on fres
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table of contentsABSTRACTPREFACEINT
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Feed type 114Measuring feed efficie
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17. Measuring soil pH 10618. Reason
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87. Keeping market-sized prawns ali
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major subject of cultivation becaus
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has little relevance, especially be
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(zoeae) are just under 2 mm long (f
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TABLE1Body segments (somites) in Ma
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Figure 5The major malemorphotypes o
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tions, where a breeding stock of bo
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most hatcheries operated on flow-th
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BOX 1Removal of iron and manganeseW
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TABLE 3Artificial brackishwater (12
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TABLE 4Diluting seawater and brine
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mentally cultured at up to 10 ppt;
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cal quality and its lack of predato
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CHOOSING YOUR SITE: SOIL CHARACTERI
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such as fertilizers and equipment.
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perate (usually originating from st
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3.2 Holding your broodstock in temp
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ing system that consists of a 300 L
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4CHAPTERHatchery phaseALL FRESHWATE
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SOURCE: HASSANAI KONGKEOand dust. T
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FIGURE17This shows the water flow t
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Figure 21The water inthese larvalta
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FIGURE24Turn-down drains are the be
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FIGURE26Installing a ring main air
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Figure 28Power supplies arenot alwa
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Water dischargeYou should take care
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is recommended. The volume of these
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then multiply to cope with the nitr
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Regular monitoringof larval waterqu
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initial stocking rates shown inBox
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Recommendations forgood larval wate
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FIGURE35Many of the larvae that go
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TABLE 8Hatchery feeding scheduleLAR
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ing to avoid BSN leaving the tank.
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TABLE10The major diseases known to
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Notes on potential disease problems
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FIGURE36aA method of evaluating the
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occurred). You are therefore recomm
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5CHAPTERPostlarval holdingand nurse
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Figure 39Substrates can beused in n
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FIGURE41Postlarvae in plastic bags
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pH and temperature of the rearing f
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It is difficult to recommend exact
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6CHAPTERGrow-out phaseFRESHWATER PR
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FIGURE44ponds may become low enough
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FIGURE46Pond banks should have the
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FIGURE50The dissolved oxygen levels
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Figure 53Where thetopography of the
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Figure 56The outletstructure,someti
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Figure 58This freshwaterprawn pondh
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FIGURE59 cont.CROSS SECTIONSOURCE:
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Figure 64Long-shaftaeratorin action
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there is only a single stocking), t
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TABLE16Lime requirements for treati
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semi-intensive stocking rates vary
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Keeping rootedplants out ofyour pon
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advantages obtained in temperate cu
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Polyculture of freshwater prawnswit
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only increases the availability of
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Using water-stable feeds provides y
Page 133 and 134: MEASURING FEED EFFICIENCYYou should
Page 135 and 136: Example of feeding ratefor freshwat
Page 137 and 138: allowed to become too low and there
Page 139 and 140: found to be hosts for the bopyrid i
Page 141 and 142: Figure 81A large BCMacrobrachiumros
Page 143 and 144: 7CHAPTERHarvesting andpost-harvest
Page 145 and 146: FIGURE83You can cull-harvest your p
Page 147 and 148: FIGURE85Larger ponds may also be cu
Page 149 and 150: Figure 91HarvestingMacrobrachiumros
Page 151 and 152: (Figure 95). To kill a batch of 50
Page 153 and 154: described earlier in this manual) a
Page 155 and 156: Once the prawns arrive at the point
Page 157 and 158: properly. They should also be displ
Page 159 and 160: ANNEX 1, Figures 1-12Macrobrachium
Page 161 and 162: 4ANNEXSource, hatching andenrichmen
Page 163 and 164: The nutritional quality and physica
Page 165 and 166: decapsulation improves the energy c
Page 167 and 168: starved versus enriched BSN. Lavens
Page 169 and 170: 1ANNEX 4TABLEDetermining hatching p
Page 171 and 172: 4ANNEX 4TABLE Hydrating and decapsu
Page 173 and 174: 7ANNEX 4TABLE1. Set up the hatching
Page 175 and 176: grades the particles and washes the
Page 177 and 178: 2. Stock estimation when postlarvae
Page 179 and 180: animal, particularly within the gil
Page 181 and 182: ANNEX 7 FIGURE1The size of the mesh
Page 183: 8ANNEXSize managementAS MENTIONED I
Page 187 and 188: ANNEX 8 FIGURE3Changing the stockin
Page 189 and 190: ANNEX 8 FIGURE4Orange claw (OC) and
Page 191 and 192: 9ANNEXFarm-made pond feedsTHIS ANNE
Page 193 and 194: ANNEX 9, Figure 3Farm-made feedsnee
Page 195 and 196: 4ANNEX 9TABLEFarm-made grow-outfeed
Page 197 and 198: which the requirements are applied.
Page 199 and 200: Carapace:Caridean:Cephalon:Chela:Ch
Page 201 and 202: Genital pores:Gill chamber:Greenwat
Page 203 and 204: Puddling:Rostrum:Salinity:Sequester
Page 205 and 206: ConversionsTHIS SECTION OF THE ANNE
Page 207 and 208: Financial considerationsSOME COMMEN
Page 209 and 210: ReferencesAlston, D.E. & Sampaio, C
Page 211 and 212: Fujimura, T. & Okamoto, H. 1972. No
Page 213 and 214: New, M.B., Singholka, S. & Vorasaya
Page 215: This new manual, which replaces an
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Farming freshwater prawns

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