malecha 1986 aquacultural-engineering

7/28/2019 Malecha 1986 Aquacultural-Engineering

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,4 quacu lmral Engineering 5 ( 1986 ) 18 3-1 97

New Techniques for the Assessm ent and Opt imalM an age m ent of Growth and Standing Crop Variation inthe Cultured Freshwater Prawn, M acrobrach iu mrosenbergi iSpencer R. M alecha

A q u a c u l t u r e R e s e a r c h P r o g r am , D e p a r t m e n t o f A n i m a l S c ie n c e s .U n i v e rs it y o f H a w a i i. 1 8 0 0 E a s t - W e s t R o a d , H o n o l u l u , H a w a i i 9 6 8 2 2 , U S A

A B S T R A C TT h e c u r r e n t ' t r a d i t io n a l ' p r a w n p o n d m a n a g e m e n t + 3 "stem r e a ll y d o e sn o t 'm a na ge ', b u t r a t h e r a c c o m m o d a t e s p r a w n p r o d u c t i o n c h a ra c -t er is ti cs a t t d w a s i n s t i tu t e d w i t h a m i n i m u m k n o w l e d g e o f p r a w nb i o l o g y a n d h u s b a n d r 3 : A s s t t c h , t h e t r a d i t i o n a l s y s t e m i s n o t o p t i ma lb e c a u s e i t d o e s t r o t r e l y o n a s t r o n g e mp i r i c a l k n o w l e d g e b a s e . P r a w nc u l t u r e h a s s u c c e e d e d u p u n t i l n o w b e c a u s e M a c r o b r a c h i u m r o s e n -b e r g i i i s e a s il y c u l t ,t r e d a t t d w i l l g i v e 5 0 0 - 1 0 0 0 k g h a - I y e a r - t w i t h o u tm u c h e ffo rt. T h i s is s u [ f ic i e n t i n ma n y a r e as o f t h e w o r m b u t t ro t i no th er+ " w h e r e e c o t t o m i c c o n d i t i o n s h a v e b r e a k - e v e n p r o d u c t i o nr e q u i r e m e n t s o f n e a r l y 1 t o n n e g r e a t e r t h a n t h is . T h e t r a d i t i o n a l sy s t e mre ly ing on se lec t ive harv es t ing wi th large se ine ne t s i s s er ious ly ine f f i-c i e n t w h i c h n o t o n l y l e a d s t o l o s t r e v e n t t e b u t t t n d e r - m a n a g e s p o n dg r o w t h s i t tc e u n c t d l e d l ar g e a n i m a l s s u p p r e ss t h e g r o w t h o f u n c u l l e ds m a l l e r o n e s . T h e d e g r e e t o w h i c h t h i s o c c tt r s w a s t ro t k / t o w n t o t h ed e s i g n e rs o f t h e t r a d i t i o n a l s y s t e m w h o h a d n o w a y oJ" k n o w i n g (a s w ed o n o w f r o n t o u r r e se a r c h r es u l ts ) t h e e x t r e m e l y la r g e c o m p e n s a t o r yg r o w t h c a p a b i l i t y o f s m a l l p r a w n s i n t h e a b s e n c e o f la rg e o n e s . T h et r a d i t i o n a l s y s t e m a l s o d o e s n o t m a n a g e s e x u a l d i n t o r p h i c g r o w t hb e c a u s e n o t e c h n o l o ~ ' e x i s ts w h i c h c a n b e u s e d t o c re a te m o n o s e xb ro od +" o r m a n i p u l a t e t h e s e x r a t io i n p o n d s . A c c u r a t e p r o d u c t i o nm o d e l s a r e n o t a v a i la b l e b e c a u s e t r a d it i o n a l p o n d s a r e r a re ly s a m p l e dat tcb 'or rarely drain ed. This , alo ng with in ef f ic ie nt han,es ts , resul ts in ac o - m i n g l i n g o f c o h o r t s t o c k i n g c la ss es . I t is i mp o s s i b l e t o g e t a c c u r a tes u r v iv a l a t td g ro w t h d a m b e c a u s e o f t h is a t t d b e c a u s e i t i s s o t i m e c o n -

183Aquactdtural Engineer ing 0 1 4 4 - 8 6 0 9 / 8 6 / S 0 3 . 5 0 - E ls ev ie r A p p li ed S c ie n ceP u b l i s h e r s L t d . E n g l a n d . 1 9 8 6 . P r i n te d i n G r e a t B r i t a in


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184 S . R . M a l e c h a

surning to sample com me rc ia l pond s and process the dam on a regu larbasis. This pa per describes fou r ne w en gineering and 'bioengineering"techn iques which are under deve lopment and can overcome a l l thedra w bac ks o f the tra dit ional system : (1) surgical se x reversal to creaternonosex broods; (2) genet ic tagging o f s tocking an d res ident cohorts toassess survival an d grow th; (3) size grading an d 100% e f icien t harvest-ing us ing pond draining and a machine grader-hare 'es ter: and [4) asern i -au tomated co mp uter ass is ted prawn sam ple da ta m a n a g e m e n tsys tem wh ich uses sonic digit ization o f praw n sam ple data .

INTRODUCTIONThe purposes of this paper are to point out the limitations of thecurrent prawn pond culture system and to give a brief description ofcomponents of one system which is predicted upon a more efficientmanagement of prawn growth variation and standing crop throughefficient harvesting, computer assisted assessment of inventory,control of sex ratio, and more accurate computer based productionmodels which use genetic tagging of prawn age and size classes and asemi-automated, computer based prawn sampling data managementsystem. All the components of the new management system are by nomeans immediately at hand; however, we can expect future prawnpond production systems to be much different from what we havetoday.

THE 'TRADITIONAU PRAWN PRODUCTION SYSTEMThe current prawn pond management system has been termed the"traditional' system (Malecha, 1983a) and involves stocking postlarvalprawns once or twice a year into earthen ponds and then selectivelyharvesting market-sized animals using seine nets. Originally thetraditional system was designed in Hawaii by Fujimura (1974) to takeadvantage of the fact that individual prawns in a pond populationexhibit highly variable growth rates, so that by culling large animalsfrom the population with nets, smaller animals could grow into thesize classes 'vacated' by the larger animals and market-sized animalscould be produced uniformly throughout the year. It had beenassumed from pilot studies that periodic stocking and periodic seine-


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G r o w t h a rz d c r o p v a r i a t i o n i n t h e f r e s l, ~ ' a te r p r a w n 1 8 5

a n d - c u l l h a r v e s t i n g c o u l d s u s t a i n p r o d u c t i o n t h r o u g h o u t m a n y y e a r so f s t o c k i n g a n d h a ~ ' e s t i n g . U n f o r t u n a t e l y t h i s d o e s n o t a p p e a r t o b et rue s ince s tock ing cohor t s do no t comple te ly d i f fe ren t ia te in to c lea rm ode l c lasses whe n ha rves t ing i s ine f f ic ien t. T he p i lo t s tud ies onwhich the t rad i t iona l sys tem i s based invo lved on ly two s tock ings ,made rough ly ' one , , ea r apa r t , which d i s t ingu ished themse lves as themodes in a b imoc l ' a l s i ze - f requency d i s t r ibu t ion tFu j imura , 1974) .A p p a r e n t l y t h e p e r i o d i c s e i n e - a n d - c u l l h a r v e s t p r a c t i c e d i n p i l o ts t u d i e s g r a d u a l l y e l i m i n a t e d t h e f i r s t s t o c k e d c o h o r t a n d t h e n w a sapp l ied to the second cohor t a s the l a t t e r g rew to inc lude ha rves tab lean imals . However , we be l i eve tha t in te r - s ize -c lass compet i t ionb e t w e e n s t o c k i n g c o h o r t s w a s m i n i m i z e d i n th e F u j i m u r a p i l o t s t u d ie sb u t i s m a x i m i z e d i n c o n t i n u o u s l y s t o c k e d a n d h a r v e s t e d , b u t r a r e l yd r a i n e d , c o m m e r c i a l p r a w n p o n d s . I n d e e d , n e t h a r v e s t s c a p t u r e 5 0 %or l e ss o f the l a rge ha rves t -e l ig ib le an imals (Lam, 1984) . The l a rgean imals remain ing in the pond u t i l i ze resources and suppress thegrowth o f smal le r an imals , de lay ing the l a t t e r g roup ' s en t ry in to theharves t c la ss . Over t ime a mix tu re o f yea r c lasses compr i se the pondp o p u l a t i o n a n d n e w l y s t o c k e d c o h o r t s m u s t c o m p e t e w i t h s lo w -growing long- te rm res iden t s and p roduc t ion i s lowered s ign i f i can t ly .In add i t ion , the ha rves tab le c lass may cause the en t i re popu la t ion toexceed the c r i ti ca l s t and in g c rop in ine f f ic ien t ly ha rves ted pon ds sotha t com pet i t io n is inc reased caus ing inc rease d morta lity '.

D E P E N S A T O R Y A N D H E T E R O G E N E O U S I N D I V I D U A LG R O W T H ( H I G )

I n a s m u c h a s t h e p r a w n ' s g r o w t h p a t t e r n c o n s t i t u t e s o n e o f i t s m o s tv i s i b l e a n d e c o n o m i c a l l y i m p o r t a n t b i o l o g i c a l c h a r a c t e r i s t i c s w ed e c i d e d to s t u d y i ts g e n e t ic a n d e n v i r o n m e n t d e t e r m i n a n t s . L i k e m o s taqua t ic spec ies the va r iance o f the s ize d i s t r ibu t io n o f Macrobrachiumrosenbergii incre ases as i t s me an increa ses , i .e . i t 'depensa tes" i Ricker ,1975) , due to the fac t tha t weight gain is a power funct ion of in i t ia lwe igh t. M os t aq ua t ic po pu la t ions wi th a non-z e ro va r iance in the i r s ized i s t r ibu t ions und ergo dep ens a t ion , bu t the ra tio o f the f ir s t and secondm o m e n t s u s u a l ly r e m a i n s r e la t iv e l y c o n s t a n t t h r o u g h t im e . P r aw n a n dc a r p p o p u l a t i o n s o n t h e o t h e r h a n d d i s p l a y h e t e r o g e n e o u s i n d i v id u a lg r o w t h ( H I G ) c h a r a c t e r i z e d b y a n i n c r e a s e d f ir st t o s e c o n d m o m e n t


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186 S. R . Malecharatio and an elevated third moment, skewness, due to the fact that aspectrum of growth functions is represented in a growing M . r o s e n -b e r g i i population resulting in skewed (to the right) size distributions(Malecha e t a l . , 1981b; Raanan, 1982). Since the prices paid forcrustaceans are a function of their size, the prawn's growth patternaffects its product value to a degree not found in other aquatic animalsand livestock. The prawns in the right-hand tail of the distribution areusually males and have been referred to as 'bulls' (Fujimura andOkamoto, 1972) and are analogous to "jumpers' in the common carp(Moav and Wohlfarth, 1974) and to "Tobi koi' in the ornamental carp(Wohlfarth, 1977). Individual prawns whose sizes lie around the popu-lation mode have been called 'runts' (Fujimura and Okamoto, 1972).

GENETIC AND ENVIRONMENTAL SOURCES OF HIGWe have found that HIG is an equilibrium state of prawn populationsand probably cannot be changed through domestication since it hashigh adaptive value. Males could vary genetically in their growth ratesand consequently the stage in which they assume a certain role, butour research has shown that heterogeneous individual growth of malesappears to be a non-genetic, socially dependent phenomenon(Malecha e t a l . , 1984). In addition, we have conducted a series ofwater table experiments in the laboratory to study HIG (Malecha e ta l . , 1981b). We found that HIG does not develop in populations ofindividually housed animals to the degree that it does in free-livingpopulations and that populations of individually housed animals withindividual water are not self-growth-inhibitory and depensate at thesame rate as flow-through portion-segregated individuals sharingcommon water. We also found that tactile, visual and water contactacross a barrier does not induce large animals to suppress the growthof smaller animals and that there were no significant differencesbetween the HIG patterns in monosex populations and in populationsof the same sex in bisexual populations. We concluded that the charac-teristic depensation patterns develop in males and females regardlessof the presence of the opposite sex. In a recent experiment we testedwhether water from a free living population of animals in rearing tankscould effect the HIG in a 'population' of individually housed animalswhen passed over them. HIG did develop in these control popula-


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t ions , sugges t ing tha t a long- l ived wa te r borne fac to r cou ld bei n v o lv e d w i th t h e a n i m a l - t o - a n im a l c o m m u n i c a t i o n n e c e s s a r y fo r H I Gt o d e v e l o p . O v e r a l l o u r r e s u l t s s h o w t h a t s m a l l p r a w n s r e t a i n a n i n -he re n t capac ity , fo r com pensa to ry , g row th ; con seq uen t ly the i r s izes a rel a rg e l y e p h e m e r a l c o n d i t i o n s b r o u g h t o n b y n o n - g e n e t i c , e x tr a -p o p u l a t i o n a l b e h a v i o r a l f a c to r s. T h i s m e a n s t h a t H I G is b e s t m a n a g e db v c o m p l e t e l y r e m o v i n g a l l t h e d o m i n a n t m a l e s s i n c e t h e i r p r e s e n c er e s tr i ct s th e t r a n s f o r m a t i o n o f s u b d o m i n a n t m a l e s i n to d o m i n a n tm a l e s a n d s m a l l m a l e s i n t o s u b d o m i n a n t o n e s . I n e f f i c i e n t r e m o v a l o fla rge an imals by ine f f i c ien t ha rves t ing which charac te r izes thet rad i t ion a l sys tem d im in i shes th i s des i red e f fec t. T ran s la ted in to p rac t i -ca l t e rms , ine f f i c ien t ha rve s t ing no t on ly rep resen t s los t r evenu e b yl e a v i n g a n i m a l s ' b e h i n d ' b u t a l s o a l l o w s a g r o w t h s u p p r e s s i o n o f t h es m a l l e r a n i m a l s b y t h e l a r g e r o n e s . We n o w a r e c o n v i n c e d t h a t t h em ajor l imi t ing fac to r in p raw n pro du c t ion i s ine f f i c ien t ha rves t ingw h i c h u n d e r - m a n a g e s t h e p r a w n s ' s o c i a l s t r u c t u r e . U n l i k e o t h e r a g r i -cu l tu ra l spec ies whos e p rod uc t io n l imi ta t ion is usua l ly a func t ion o fenergy-based inpu ts ( feeds , f e r t i l i ze r ) and an imal b iomass (dens i ty ands ize) , a p raw n pop ula t io n ' s b iom ass and y ie ld is con t ro l l ed a nd l imi tedby i ts socia l s t ructu re .

O P T I M U M M A N A G E M E N T O F H I G - - S I Z E G R A D E D ,S T O C K D I V I D E D A N D E F F IC I E N T L Y H A R V E S T E DS Y S T E M SO n t h e b a s i s o f t h e r e s u l t s d e s c r i b e d a b o v e w e h a v e d e s i g n e d a n dt e s t e d i n r e s e a r c h p o n d s a n e w p r a w n s t o c k m a n a g e m e n t s y s t e mt h e o r e t ic a l l y d e s c r i b e d i n M a l e c h a e t a l . (1981a) . Our resu l t s f romover four yea rs o f fi e ld tr i a ls have sh ow n tha t e f f i c ien t ha rves t ing has ad r a m a t i c e f f e c t o n t h e c o m p e n s a t o r y g r o w t h c a p a b i l i t y o f s m a l l e rp r a w n s a n d t h a t s i z e - g r a d i n g o f p r a w n s a n d s t o c k i n g b y s i z e c l a s s e sshor tens the t ime to f i r s t ha rves t and the overa l l tu rnover t ime o f thep o n d p o p u l a t i o n . H i g h p r o d u c t i o n r a t es w e r e a c h ie v e d b e c a u s e t h et es t p o p u l a t i o n s w e r e h a r v e s t e d w i th 1 0 0 % e f f ic i e n c y u s in g p o n dd r a i n d o w n a n d a m a c h i n e g r a d e r ( d e s i g n e d a n d f a b r i c a t e d b y t h eU n i v e r s i t y o f H a w a i i , D e p a r t m e n t o f A g r i c u l t u r a l E n g i n e e r i n g ) . A l la n i m a l s w e r e 'h a r v e s t e d o u t ' o f b o t h e x p e r i m e n t a l a n d c o n t r o l p o p u l a -t io n s w i th i n 1 2 m o n t h s . P r o d u c t i o n p e r u n i t t im e a n d a r e a w a s g r e a t e st


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188 S. R. Malecha

in the s ize -graded sys tem due to the h igh tu rnover o f the l a rge s ize -g r a d e d c l as s e s a n d t h e i n c r e a s e d c o m p e n s a t o r y g r o w t h o f t h e s m a l l e ran imals . Also , t ime to f i r s t ha rves t was sooner in the s ize -gradedsys tem.

S E X U A L D I M O R P H I C G R O W T H A N D S E XD E T E R M I N A T I O NIn z ~ 4 a c r o b r a c h i u m r o s e n b e r g i i f e m a l e g r o w t h b e g i n s t o s h a r p l y l e v e lo f f m u c h e a r l i e r t h a n m a l e g r o w t h . S e x u a l d i m o r p h i c g r o w t h f o ll o w i n gt h e o n s e t o f s e x u a l m a t u r i t y , a c o m m o n p h e n o m e n o n , i s u s u a l l ym a n a g e d d i r e c t l y in a n i m a l p r o d u c t i o n . F o r e x a m p l e , i n p o u l tr y s e x u ald i m o r p h i c g r o w t h i s m a n a g e d b y t h e s l a u g h t e r i n g o f b r o i l e r h e n se a r l i e r t h a n c o c k s . A n a l o g o u s l y , t h e o p p o s i t e h a p p e n s i n M . r o s e n -berg i i . Males a re ha rves ted f i r s t and females a re a l lowed to g row un t i lt h e y r e a c h m a r k e t w e i g h t a t a s i z e l a r g e r t h a n t h e i r o p t i m u m . T h i sr e p r e s e n t s t h e w o r s t p o s s i b l e m a n a g e m e n t o f s e x u a l d i m o r p h i cg r o w t h . B e t t e r m a n a g e m e n t o f s e x u a l d i m o r p h i c g r o w t h i s n e e d e d .T h i s c o u l d b e d o n e i f t h e r e w e r e s o m e m e a n s o f g e n e r a t i n g a l l- m a l ea n d / o r a l l- f e m a l e b r o o d s .In ve r tebra tes , s t e ro ids p roduced in the gonads cause sex d i f fe ren-t ia t io n . I n d e e d , m o n o s e x b r o o d s a r e p r o d u c e d i n f is h e s e i t h e r t h r o u g hd i r e c t a p p l i c a t i o n o f s e x s t e r o i d s t o f r y o r f r o m m a t i n g s o f n o r m a lp a r e n t s a n d p a r e n t s w h o s e s e x h a s b e e n r e v e r s ed b y s e x s t e r o id a p p l i -ca t ion . Unfor tuna te ly th i s t echno logy i s no t use fu l s ince read i ly ava i l -ab le ve r tebra te sex s te ro ids have l imi ted e f fec t in c rus taceans .H o w e v e r , u n l i k e fi sh e s , i n M a l a c o s t r a c a n c r u s t a c e a n s t h e g a m e t o g e n i ca n d e n d o c r i n e f u n c t i o n s a r e s e p a r a t e d r e s p e c t i v e l y i n t o d i s t i n c to r g a n s , t h e a n d r o g e n i c g l a n d a n d g o n a d .T h e a n d r o g e n i c g l a n d p r o d u c e s a h o r m o n e r e s p o n s i b l e f o r t h ed i f f e r e n t i a t i o n o f m a l e s e c o n d a r y s e x u a l c h a r a c t e r i s t i c s a n d i n t e r n a lg e n i ta l a n d g a m e t o g e n i c o r g a n s ( C h a r n i a u x - C o t t o n e t a l . , 1 9 6 6 ;T h a m p y a n d J o h n , 1 9 7 3 ). T h e g l a n d w a s f ir s t d i s c o v e r e d b y C h a r -n i a u x - C o t t o n ( 1 9 5 4 ) a n d s h o w n b y h e r (1 9 5 9 ) a n d o th e r s ( K a ta k u r a,1 9 5 9 , 1 9 6 0 ) t o b e c a p a b l e o f m a s c u l i n i z in g a fe m a l e w h e n t r a n s -p l a n t e d i n to t h e l at te r . R e c e n t l y N a g a m i n e e t a l . ( 1 9 8 0 a ) h a v e s h o w nthese effects in M . r o s e n b e r g i i . N a g a m i n e e t a l . ( 1 9 8 0 b ) s h o w e d t h a ta n d r e c t o m i z e d m a l e s d e v e l o p i n t o f e m a l e s w i t h a n o v a t e s t e s c a p a b l e


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Growth and c rop var ia t ion in the . lZreshwater prawn 189

o f o o g e n e s i s . K a t a k u r a ( 1 9 6 1 ) p r o d u c e d v i ab l e a ll -f e m a le p r o g e n yf r o m t h e m a t in g o f a m a s c u l i n iz e d a n d n o r m a l f e m a l e is o p o d .

I t i s p o s s i b l e t h a t m o n o s e x , o r a l t e r e d s e x r a t i o p o p u l a t i o n s c o u l db e c r e a t e d b y m a t i n g a p h e n o t y p i c a l l y s u r g ic a ll y s ex r e v e r s e d p a r e n tw i t h a g e n e t ic a l ly b u t n o t p h e n o t y p i c a l l y i d e n t i c a l n o r m a l p a r e n t .D e p e n d i n g h o w s e x c o n t r o l i s i n h e r i t e d , t h e r e a r e m a n y p o s s i b l e o u t -c o m e s f r o m s u c h c r o s s e s . I t is s a fe t o a s s u m e t h a t s e x d i f f e r e n t i a ti o n i np r a w n s , a s it is i n o t h e r D e c o p o d c r u s t a c e a n s , i s u n d e r t h e c o n t r o l o f ag e n ic a n d / o r c h r o m o s e x u a l h o m o - a n d h e t e r o - g a m e t i c s y st em .

W e h a v e b e e n d i r e c t i n g r e s e a r c h t o w a r d r a p i d l y p e r f o r m i n g t h es u r N c a l i m p l a n t a t i o n o f a n d r o g e n i c g l a n d t is s u e in t o s m a l l s e x ua ll yu n d i f f e r e n t ia t e d p u t a ti v e f e m a l es . O u r a p p r o a c h is t o p e r f o r m a s m a n yi m p l a n t s a s p o s s i b l e a n d t o p r o g e n y t e s t t h e p u t a t i v e s e x r e v e r s e dp a r e n t s .

T a b l e 1 s h o w s p u t a t i v e g e n o t y p e s o f p a r en t s , t h e ir p r o g e n y , a n dp r o g e n y s e x r a t i o s i n c r o s s e s b e t w e e n a n o r m a l p a r e n t a n d t r a n s -p l a n t e d f e m a l e s r e v e r s e d t o n e o - m a l e s , a b l a t e d m a l e s re v e r s e d t o n e o -f e m a l e s , o r i n c o r r e c t l y s e x e d r e c i p i e n t s o r a b l a te e s . O n l yc h r o m o s o m a l g e n o t y p e s a r e s h o w n . X X , X Y , Y Y , X O a r e a n a l o g o u st o H H , H h , h h , H o g e n o t y p e s w h e r e H a n d h a r e s e x d e t e r m i n i n gg e n e s .

T a b l e 2 d e p i c t s a p o s si b le s c e n a r i o f o r h y p o t h e t i c a l c o m m e r c i a ls c a le a p p l i c a ti o n o f c u lt u r i n g m o n o s e x b r o o d s b a s e d o n s u r g ic a l s exr e v e r s a l. 'B o t t l e n e c k l e v e l' ( C o l u m n 1) s ig n i fi es c e r ta i n p r o d u c t i o n o rm o r t a li t y a s s u m p t i o n s g i v e n in th e f o o t n o t e . T h e s c e n a r i o is b a s e d o na f a r m o f 4 5 0 0 h a ( 1 0 0 a c r e s ) w i t h a d u l t s t a n d i n g c r o p o f 1 0 i n d i -v i du a ls m - " o r 1 0 0 0 0 0 h a - ~ = 4 - 4 x l 0 ~' f a rm -~ (1 i n di v id u a lft -2 = 4 4 0 0 0 a c r e - l = 4 . 4 x 1 0 ~ f a r m - t ) .

M E T H O D S F O R D E V E L O P I N G M O R E A C C U R A T EP R O D U C T I O N M O D E L S

G e n e t i c t a g g in g o f s t o c k i n g c o h o r t sT h e r e is a l a ck o f a c c u r a t e p r o d u c t i o n m o d e l s i n p r a w n c u l t u r e d u e tot h e f a c t t h a t a s t r o n g e m p i r i c a l d a t a b a s e d o e s n o t e x i s t t o s u p p o r t t h ea s s u m p t i o n s o f t h e m o d e l s . T h e r e a s o n f o r th is is t w o f o ld . F ir s t, p r a w nf a r m e r s d o n o t f r e q u e n t l y s a m p l e t h e i r p o n d s b e c a u s e o f h i g h l a b o r


8/15

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9/15

G r o w t h a n d c r o p v a r i at i on i n t h e f r e s h w a t e r p r a w n

T A B L E 2

191

B o t t l e n e c k E s t i m a t e d D e s c r i p t i o nl ev e l ~ n u m b e r s

4 4 0 0 0 0 06 t

5 8 6 0 0 0 05

9 7 6 6 6 0 04 t

1 0 8 5 1 7 7 83 t"~17

2 7 11

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S t a n d i n g c r o p n u m b e r p e r 1 0 0 a c r e s ( a p p r o x . 4 5 h a )7 5 % p o n d s u rv i v alP L S s t o c k e d6 0 % h a t c h e r y s u rv i v alV i a b l e l a r v a e h a t c h e d9 0 % h a t c h r a t e (e g g t o l a r v a e )V i a b l e f e r ti l iz e d e g gs s p a w n e d5 0 0 0 0 e g g s p e r f e m a l e sG r a v i d f e m a le s8 0 % m a t i n g su c c e ssR e p r o d u c t i v e c o m p e t e n t p a r e n t s" 5 0 % s u c c e s s r a t e "S u r g i c a l l y m a n i p u l a t e d a n i m a l s

" A s s u m p t i o n s a n d / o r s o u r c e f or e a ch b o t t l e n e c k le ve l: 6 - - S m i t h et a l . ( 198 1 ) ; 5 - -e s t im a t e b a s e d o n p e r f o r m a n c e s o f th r e e c o m m e r c i a l an d o n e g o v e r n m e n t h a t c h e r i esin H a w a i i ( M a l e c h a , 1 9 8 3 a ) ; 4 - - a s s u m p t i o n o n l y - - n o p u b l i s h e d d a t a a v a i l a b le o nt h e r e l a t io n s h i p o f n u m b e r o f fe r ti l iz e d s p a w n e d e g g s a n d n u m b e r o f v i a b l e l a r v a eh a t c h ed ; 3 - - b a s e d o n a b o u t 5 0 0 0 0 e g g s p e r fe m a l e. M a l e c h a ( 1 9 8 3 a ) s h o w e d t h at al a b o r a t o r y - r e a r e d 4 5 g f e m a le c an p r o d u c e o v e r 4 0 0 0 0 e g gs p e r sp a w n , a n d f e c u n d -i ty , K is r e l a t e d to l en g t h . X , b y t h e e q u a t i o n Y = 0 -0 0 6 X ~ : ; 2 - - f r o m M a l e c h a et a l .( 1 9 8 4 ) ; t - - e s t i m a t e d a c h i e v a b l e p r o j e c t g o a l - - 5 0 % o f s u r g i c a ll y m a n i p u l a t e d a n i -m a l s s u r v i v e to p r o d u c e v i a b l e o f f s p ri n g .

c o s t s a n d t h e i n c o n v e n i e n c e o f o b t a i n i n g , r e c o r d i n g , r e d u c i n g a n da n a l y z i n g m e a s u r e m e n t d a t a. T h e c o s t o f o b t a i n i n g a n i m a l s b y s e i n i n gi s m i n o r c o m p a r e d t o d a t a m a n a g e m e n t . S e c o n d , a l m o s t a l l p r a w nf a r m s u se th e t ra d i t i o n a l p o n d m a n a g e m e n t s y s t e m ( M a l e c h a , 1 9 8 3 b )w h e r e b y p o n d s a r e p e r i o d i c a ll y s t o c k e d a n d h a r v e s t e d w i t h o u t c o m -p l e t e p o n d d r a i n i n g a n d r e s t o c k i n g . T h i s r e s u l t s i n a n a d m i x t u r e o fs tock ing to res iden t pond cohor t s and i t i s imposs ib le to assess thed e g r e e t o w h i c h t h is is o c c u r r i n g a n d t o d e t e r m i n e g r o w t h r a te , g ro w t hpa t te rn , su rv iva l , and t ime o f en t ry to ha rves t o f these cohor t s oncem u l t i p l e s t o c k i n g h a s p r o g r e s s e d . B e c a u s e o f t h i s , c o m m e r c i a l p r a w nf a r m i n g i s c h a r a c t e r i z e d b y u n q u a n t i f i e d a s s u m p t i o n s r e g a r d i n g t h ep e r c e n t h a r v e s t a b l e a n i m a l s a n d t h e m o v e m e n t s o f t h e s i z e d i s t r i b u -t ion in res iden t and s tock cohor t s mode l c lasses . In e f fec t , commerc ia l


10/15

192 .5. R. M ale ch apraw n f a rmer s have r ea l ly no eco nom ica l l y v i ab le p r ec ise way o fa s se s sing t he i r s t and ing c rop , p r ed i c t i ng t he ir ha rves t s and deve lop ingaccura t e p roduc t i on mode l s and cash f l ow p ro j ec t i ons based oninventory , assessmen t . Al l - in-a ll , p raw n fa rming rem ains l a rge ly a ' h i t-or-miss" a f fa i r de pe nd en t u po n "what com es o ut ' a t the h arves t.An ef f ic ient way of t agging prawns according to the i r s tockingcohor t t ype i s c l ea r l y needed . However , mark ing t housands o fs tocking juveni les needed for assess ing growth , surv iva l and harves t -ing pa t te rns i s imposs ib le wi th cur rent t agging technology. For th i sreaso n we have dev e lop ed a gene t ic tag u t il iz ing na tura l ly occur r ing ,e l ec t roph ore t i ca l l y de t ec t ab l e gene t i ca ll y con t ro l l ed enzym e va r ian t sca l led ' a l lozymes ' .F i r s t we have e s t ab l i shed b roods tock ca r ry ing r a r e a l l ozymes i n al a rge e l ec t rophore t i c su rvey o f Hawa i i an p rawns . Con t ro l l ed c ros sesa m o n g t h e s e b r o o d s t o c k a r e p r o d u c i n g p o p u l a t i o n s o f g e n e t i c a l l yt agged s t ock ing cohor t s wh ich can be ea s i l y d i s t i gu i shed f rom o the rs tock ing coho r t s and r e s iden t pond coh or t s .W e h a v e s h o w n ( H e d g e c o c k et a l . , 1979; Ste lmach, 1980) foura l lozyme sys tems to be var iable in the Hawai ian cul t ivar of M a c r o -b r a c h i u m r o s e n b e r g i i ca l led the "Anu enue s t ra in ' (Malecha , 1980) . Wehave se l ec t ed g lu t ama te oxa loace t a t e t r ansaminase (Got - l ) and phos -pho g lucom utase (Pgm ) fo r t h is s t udy s i nce t hey a r e t he m os t po ly -m orph ic a l lozy m e sys tems , they a re eas ies t to assay , and thev a re ra re .T he no m enc l a tu re fo r t he two a l l ozyme syst ems i s show n in Tab l e 3 .

T A B L E 3

G o re sy s t em A l l e l e s g ' ge tw s )Go t-1 103, 100 , 94~ m 1 00 , 9 7

Ea ch a l le l ic gene , as a segm ent of the gene t ic mater ia l , cont ro l s thesyn thesi s o f one p ro t e in enzym e wh ich is r evea led a s a zone o r ban dby h i s t ochemica l s t a in ing on a s t a r ch ge l fo l lowing e l ec t rophores i s o fmusc l e homogena t e s ex t r ac t ed f rom wa lk ing l egs o f s ampled andha rves t ed p rawns .


11/15

G r o w t h a n d c r o p v a r ia t io n i n t h e f r e s h w a t e r p r a w n 193T A B L E 4

O b s e r v e d F r e qu e n c ie s o f C o m m o n a n d R a r e G e n o t y p e s a t th e G o t -1a n d P g m L o c i B a s e d o n a S u r v e y o f 2 0 0 0 A d u l t P r a w n s C o l l e c te d f r o mC o m m e r c i a l P o n ds

G e n e s y st em C o m m o n R a r ege no ~'p es geno~. 'pes

G o t - I 1 0 0 / 1 0 0100/1031 0 0 / 9 4 1 0 3 / 1 0 3

F r e q u e n c yPgm

9 6 " 7 4 % 0 .7 %lO0/100lOO/97 97,/97

F req u en c y 9 9 .0 % 1 .0 %

9 4 / 9 4 1 0 3 / 9 4

1-07% 1-49%

F o r G o t - l , s i x d i p l o i d g e n o t y p e s m a y b e f o r m e d f r o m t h e t h r e ea ll e le s , w h i l e t h r e e d i f f e r e n t d i p l o i d g e n o t y p e s a r e p o s s i b l e f o r t h e P g ms y s te m . T h e s e a r e l is te d a n d g r o u p e d i n T a b l e 4 in t o t h e c o m m o n a n dr a r e g e n o t y p e s d e t e c t e d i n a s u r v e y w e c o n d u c t e d o f 2 0 0 0 a d u l tp r a w n s c o l l e c te d fr o m c o m m e r c i a l p o n d s . A s c a n b e s e e n in T a b l e 4 ,o v e r 9 6 % o f t he c o m m e r c i a l H a w a i ia n p r a w n p o n d p o p u l a ti o n s h a v ec o m m o n G o t -1 g e n o ty p e s a n d 9 9 % h a ve c o m m o n P gm g e n ot y pe s .T h e r e f o r e , s t o c k e d c o h o r t s w h i c h a r e h o m o z y g o u s o r h e t e r o z y g o u sf o r a n y o f t h e r a r e g e n o t y p e s c a n b e r e a d i ly d i s ti n g u i s h e d f r o mr e s i d e n t p o p u l a t i o n s w i t h a n e r r o r p r o p o r t i o n a l t o t h e n a t u r a l l yo c c u r r i n g f r e q u e n c y o f t h e r a r e g e n o t y p e s i n v o l v e d .

T h e g e n e t i c t a g g in g o f c o h o r t s w i ll a l lo w a v e r y a c c u r a t e a s s e s s m e n to f t h e d e g r e e t o w h i c h a d m i x t u r e o c c u r s w i th i n a n d b e t w e e n s t o c k in ga n d p o n d r e s i d e n t c o h o r t s a n d it w i ll t h e n b e p o s s i b l e to a ss ig na c c u r a t e r e s i d e n t t im e s a n d p r o b a b i l it ie s o f s u r vi v al a n d g r o w t ha m o n g s t o c k i n g c o h o r t s a n d b e t w e e n s i z e c l a s s e s w i t h i n a s t o c k i n gc o h o r t . T h i s i n f o r m a t i o n i s e s s e n t i a l f o r d e v e l o p i n g p r o d u c t i o n s i m u -l a t i o n m o d e l s f o r a p o n d s y s t e m w h e r e h a r v e s t i n g i s n o t e f f i c i e n t , t h ep o n d s a r e n o t d r a i n e d a n d t h e a g e s tr u c t u r e o f th e r e s i d e n t is n o tk n o w n .


12/15

194 S . R . M a l e c h aC O M P U T E R B A S E D S A M P L IN G D A T A M A N A G E M E N T

W e h av e d e v e l o p e d c o m p o n e n t s o f a c o m p u t e r b a s e d d a t a a c q u is it io na n d a n a l y s i s s y s t e m w h i c h c o u l d g r e a t l y r e d u c e t h e c o s t o f c o m m e r c i a lp r a w n p o n d s a m p l in g d a t a m a n a g e m e n t .T h e m a i n f e a t u r e o f t h e s y s t e m i s t h a t p r a w n l e n ~h s a r e d i g i t i z e di n s t a n t a n e o u s l y a n d r e c o r d e d , c o m p i l e d a n d s t o r e d i n am i c r o c o m p u t e r . L a b o r i s r e d u c e d b y h a l f a n d t h e m a t e r ia l s h a n d l i n g

(e.g . p raw ns , ru le r s, da ta shee t s , han d ca lcu la to rs , ne t s , e tc . )i s r educe dto a f rac t ion o f tha t r equ i red in the p re sen t sys tem.F i g u r e 1 s h o w s t h e g e n e r a l o r g a n i z a t i o n o f t h e s y s t e m w h i c h w e a red e v e l o p i n g . A s l i d e i m a g e o f p r a w n s i s o b t a i n e d b y p h o t o g r a p h i n gi n d i v i d u a l s s c a t t e r e d o n t o a f i a t s u r f a c e u s i n g a w a t e r p r o o f c a m e r ac o n t a i n i n g P o l a ro i d 3 5 m m t r a n s p a r e n c y ( sl id e ) fi lm w h i c h c a n b ed e v e l o p e d o n t h e s p o t u s i n g t h e P o l a r o i d A u t o p r o c e s s o r . H i g hcon t ras t , h igh qua l i ty images a re no t requ i red fo r the sys tem to work ;on ly the p rawn 's "o rb i t l eng th ' (d i s tance be tween the eyes ta lk o rb i tpos te r io r su r face and the t ip o f the t e l son) has to be d i sce rn ib le on thep r o j e c t e d i m a g e . In p r a c ti c e , e v e n a c l o u d y o r p o o r q u a l i ty im a g e c a n

be measured a t l eas t a s accura te ly as i s p resen t ly done wi th a ru le r o rca l ipe r . S l ide images a re p ro jec ted (us ing a s t andard ca rouse l p ro jec -t o r ) o n t o t h e b a c k o f a s e m i - o p a q u e w i n d o w m o u n t e d i n t h e s i d e o f apro jec t ion cab ine t . Two mir ro rs ins ide the cab ine t ca r ry the s l ide

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_1Fig. 1. Flow iagram or sonicdigitization f prawn engths nd dataanalysis.


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Grow th and crop variation in the freshwater prawn 19 5i m a g e f r o m t h e s l i d e p r o j e c t o r l o c a t e d o n t h e f l o o r o f t h e c a b i n e t t ot h e p r o j e c t i o n w i n d o w . A G r a f / B a r S o n i c D i g it iz e r ( M o d e l G P - 7 ,S c i en c e A c c e s s o r ie s C o r p o r a t i o n , W e s tp o r t, C o n n , U S A ) is m o u n t e do n t h e p r o j e c t i o n c a b i n e t o u t i n f r o n t o f a n d o n t o p o f t h e i m a g ep r o j e c t i o n w i n d o w . A s ty lu s, e l e c tr o n i c a l ly c o n n e c t e d t o t h e G r a f / B a rm a i n c h a s si s, is c a p a b l e o f e m i t t i n g a n e l e c t r o n i c s ig n a l a n d a s o n i cs o u n d w h e n i t s t i p i s d e p r e s s e d b y t o u c h i n g a p o i n t w i t h i n t h e a c t i v ea r e a . T h e e l e c t r o n i c si g n a l is c a b l e d b a c k t o t h e c h a ss is . M i c r o p h o n e sl o c a t e d o n t h e c h a s s i s e n d s p i c k u p t h e s o n i c s ig n a l f r o m a st yl us . T h er e l a ti v e ti m e t h e s i g n a l t a k e s t o r e a c h e a c h o f th e m i c r o p h o n e s i s t h e nr e c o r d e d b y t h e d e v i c e a n d t h e C a r t e s ia n c o o r d i n a t e s o f t h e p o i n tr e l a ti v e to a n o r i N n i n t h e r e f e r e n c e c o r n e r o f th e a c t iv e a r e a is d e t e r -m i n e d . T h e s e c o o r d i n a t e s a r e t h e n t r a n s m i t t e d a s A S C I I d a ta t o t h ea s y n c h r o n o u s c o m m u n i c a t i o n s p o r t o f a m i c r o c o m p u t e r by a n R S 2 3 2c o n n e c t o r . T h e p r o g r a m w h i c h w e w r o t e t h e n r e c o r d s t h e s e c o o r d i -n a t e s. A l l s o f t w a r e f o r i n p u t m a n a g e m e n t a n d a n a l ys is o f t h e d a t a i sw r i t t e n i n A d v a n c e d I B M P C B A S I C . T h e s o f t w a r e i s u s e r - f r i e n d l ya n d m e n u d r i v en . W h e n t w o p o i n t s (a t e i t h e r e n d o f th e p r a w n i m a g e )h a v e b e e n d i g i t i z e d t h e p r o g r a m c a l c u l a t e s t h e d i s t a n c e b e t w e e n t h ep o i n t s a n d c o n v e r t s t h i s t o a n a c t u a l l e n g t h b y t h e s c a l i n g r u l e o r as t a n d a r d o f k n o w n l e n g th , a n d t h e n c a l c u l a t e s t h e a n i m a l w e i g h t.

A n a l y s e s p r o g r a m s w h i c h c o n v e r t t h e l e n g th s to w e i g h t s g e n e r a t ew e i g h t f r e q u e n c y h i s t o g r a m s a n d s ta t is ti c s, p l o t t h e m e a n w e i g h t o f th ep o n d p o p u l a t i o n a g a in s t ti m e , a n d p r i n t o u t h a r d c o p i e s o f a j u x ta -p o s i t i o n o f h i s t o g r a m s a n d s ta t is ti cs i n c h r o n o l o g i c a l o r d e r , p o n dn a m e a n d s t a rt a n d e n d d a t e s.

R E F E R E N C E SCharn iaux-Cot ton , H . (1954) . Ddcouv er te chez un Crustace Am phip ode( Orches t ia gamare l la ) d'une g lande en do cr ine respo nsable d e la di ffdrencia-t ion des caract~res sexuels premieres et secondaires males. C. R. Hebd.SOances A c a d Sci. S&. D, Sci. Nat ., 2 3 9 , 7 8 0 - 2 .Charniaux -Cot ton, H. (1959) . M ascul inizat ion des feme l les de la Cre ve t te/ ihe r maphr od i s me p r o t &andr i que Lysmata se t icauda ta , par greffe de D~ca-podes. Note prdliminaire. C. R. H ebd . S~a nce s Ac ad . Sci. SSr . D, Sci. Nat. ,2 4 9 , t 5 8 0 - 2 .Charniaux-Cotton, H. , Zerbib, C. & Meusy, J . J . (1966). Monographie de laglande androg ~ne d es crus taces supdr ieurs . C m s t a c e a n a , 10, 113-3 6 .


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196 S. R. 3IalechaF u j im u r a , T . ( 1 97 4 ) . J o b c o m p l e t io n r e p o r t - - D e v e l o p m e n t o f a p r a w ni n d u s t r y in H a w a i i, J u l y 1 , 1 9 6 9 t o J u n e 3 0 . 1 9 7 2 . U S D e p t . C o m m e r c e ,

N O A A N M F S , 2 1 p p .F u j im u r a , T . & O k a m o t o , H . ( 1 9 7 2 ). N o t e s o n p r o g r e s s m a d e in d e v e l o p i n g am a s s c u l t u r i n g t e c h n i q u e f o r Macrobrachium rosenbe~ii i n H a w a i i . I n :Coastal Aq uac tdture in the Indo-Pacific Region, e d . T . V . R . P i l l a r . F i s h i n gN e w s B o o k s , L td , L o n d o n .H e d g e c o c k , D ., S t e l m a c h , D . J., N e l s o n , K ., k i n d e n f e l s e r , M . E . & M a l e c h a , S.R . ( 1 9 7 9 ). G e n e t i c d i v e r g e n c e a n d b i o g e o g r a p h y o f n a tu r a l p o p u l a t io n s o fMa crobrachiurn rosenbergii. Proc. W orld Ma ricul. Soc., 1 1 , 5 0 0 - 2 8 .K a t a k u r a , Y . ( 1 9 5 9 ) . M a s c u l i n i z a t io n t h r o u g h i m p l a n t i n g t es t es i n to t h ef e m a l e Arrnadillidium vtdgare, a s i s o p o d c r u s t a c e a n . Proc. Jpn . Acad. , 3 5 ,9 5 - 8 .K a t a k u r a , Y . ( 1 9 6 0 ) . T r a n s f o r m a t i o n o f o v a r y i n t o t e s te s fo l l o w i n g i m p l a n t a -t io n o f a n d r o g e n o u s g l a n d s i n Armadillidiurn vulgare, a n i s o p o d c r u s t a -c e a n . Annot. Zool. Jpn. , 3 3 , 2 4 1 - 4 .K a t a k u r a , Y . ( 1 9 6 1 ). P r o g e n y f r o m t h e m a t i n g o f t h e n o r m a l f e m a l e a n d t h em a s c u l i n i z e d f e m a l e o f Armadill iditml vulgare, a n i s o p o d c r u s t a c e a n .Annot. Zool. Jpn., 3 4 (4 ), 1 9 7 - 9 .L a m , C . Y . ( 1 9 8 4 ) . F o r e c a s t i n g f r e s h w a t e r p r a w n h a r v e s t y i el d s. M S c T h e s i s .D e p t . A g r i . E n g . , U n i v e r s i t y o f H a w a i i, H a w a i i. 6 1 p p .M a l e c h a , S. R . ( 1 9 8 0 ) . D e v e l o p m e n t a n d g e n e r a l c h a r a c t e r i z a ti o n o f g e n e t i cs t o c k s o f Macrobrachium rosenbergii a n d t h e i r h y b r i d s f o r d o m e s t i c a t i o n .Universi~' o f Hawaii, Sea Grant Quarterl), 2 (4) , 6 pp.M a te c h a , S . R . ( 1 9 8 3 a ). C o m m e r c i a l s e e d p r o d u c t i o n o f th e f r e sh w a t e r p r a w nMacrobrachium rosenbergii. In : CR C Ha ndb ook of Marine Science Vol. LAquaculture of Crustaceans, e d . J . P . M c V e y , C R C P r e s s , B o c a R a t o n .F l o r id a , p p . 2 0 5 - 3 0 .M a l e c h a , S. R . ( 1 9 8 3 b ). C o m m e r c i a l p o n d p r o d u c t i o n o f t h e fr e s h w a t erp r a w n Macrobrachium rosenbergii. In : CR C Han dbook o f Marine Sc ienceVol. L Aquaculture of Crustaceans, e d . J . P . M c V e y , C R C P r e s s , B o c aR a t o n , F l o r i d a, p p . 2 3 1 - 5 9 .M a l e c h a , S . R . , P o l o v i n a , J . & M o a v , R . ( 1 9 8 l a ). A m u l t i - s t a g e r o t a t i o n a ls t o c k i n g a n d h a r v e s t i n g s y s te m f o r y e a r r o u n d c u l t u r e o f t h e f r e s h w a t e rp r a w n , Macrobrachitml rosenbergii . U N I H I - S E A G R A N T - T R - 8 1 - 0 1 .U n i v e r s it y o f H a w a i i.M a l e c h a , S . R . , B i g g e r , D . , B r a n d , T . , L e v i t t , A . , M a s u n o , S . & W e b e r , G .( 1 9 8 1 b ). G e n e t i c a n d e n v i r o n m e n t a l s o u r c e s o f g r o w t h p a t t e r n v a r i a ti o n i nt h e c u l t u r e d f r e s h w a t e r p r a w n , Macrobrachium rosenbe~ii. P a p e rp r e s e n t e d a t W orld Conference on Aquaculture, Septem ber 21-25 , 1981,V e n i c e , I t a ly .M a l e c h a , S . R . , M a s u n o , S . & O n i z u k a , D . ( 1 9 8 4 ) . T h e f e a s i b i l i t y o f m e a s u r -i ng t h e h e r i ta b i li ty o f g r o w t h p a t t e r n v a r i a ti o n i n j u v e n i l e fr e s h w a t e rp r a w n s , Macrobrachium rosenbergii ( d e M a n ) . Aquaculture, 3 8 , 3 4 7 - 6 3 .M o a v , R . & W o h l f a r t h , G . ( 1 9 7 4 ) . C a r p b r e e d i n g in Is r a el . I n : Aqllacultura/Genetics, e d . R . M o a v , J o h n W i le y a n d S o n s , N e w Y o r k , p p . 2 9 5 - 3 1 8 .


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Grow ttt and crop variation in the fresh water pn tw n 19 7Na gam ine , C., Knigh t . A . W. , M aggen t i . A . & Pa .xmen , G. ~1 9 8 0 a i . Mas cu -l in iza t ion o f female Ma cr o b r a ch iu m r o s en b er g i i ( d e M a n ) ( D e c a p o d a :

P a l a e m o n i d a e ) b y a n d r o g e n i c g l a n d i m p l a n t a ti o n . Gen, Comp. Endocr in . ,4 1 , 4 4 2 - 5 7 .Nagamine , C. . Knigh t , A . W. , Maggen t i , A . & Paxmen , G. (1980b) . Ef fec t s o fa n d r o g e n i c g la n d a b l a ti o n o n m a l e p r i m a r y a n d s e c o n d a r y s e xu a l c h a r a c -te r i s t i cs in the Malays ian p rawn, 3 , lacrobrach ium rosenberg i i ( d e M a n )(D ec ap o d a : Pa l aem o n i d ae ) , w i th f i rs t ev i d en ce o f i n d u ced f em i n i za t io n in an o n - h e r m a p h r o d i t ic d e c a p o d . Gen. Comp. Endocr in . , 4 1 , 4 2 3 - 4 1 .Raan an , Z . (1 9 8 2 ) . T h e o n t o g en y o f s o c i a l s t ru c t u re i n t h e f r e s h w a t e r p r aw nMa cr o b r a ch iu m r o s en b er g i i !d e Man ) . Ph D T h es i s , H eb rew U n i v e r s i t y ,Je rusa lem , I s rae l , l 01 pp .P i ck e r . W . E . (1 9 75 ) . C o m p u t a t i o n an d i n t e rp re t a t i o n o f b io l o g ica l s ta t is ti c sfo r f i sh po pu la t ions . Bull. Fish. Res. Bd. Can., 191 , 38 l.Sm ith . T. I. J ., Sa ndifer , P. A. , Jen kins , W . E. & Stoc kes , A. D. ( 1981 ). Eff ect ofp o p u l a ti o n s t r u c t u r e a t s to c k i ng a n d d e n s i ty o n p r o d u c t i o n a n d e c o n o m i cp o t en t i a l o f p r aw n (Macrobrach ium rosenberg i i ) f a rmi n g i n t emp era t ec l imates . Proc. W orld M aricul. Soc., 1 2 , 2 3 3 - 5 0 .S t e l mach , D . J . ( 1 9 8 0 ) . E l ec t ro p h o re t i c v a r i a t i o n i n Ma cr o b r a ch iu m r o s en -b e rg ii : ev i d en c e fo r s u b s p ec i f ic v a r ia t io n . M Sc T h es i s , D ep t . o f G e n e t i c s ,U n i v e r s i t y o f H aw a i i. H aw a i i , 4 0 p p .T h am p y , D . M. & J o h n , P . A . (1 9 7 3 ) . O b s e rv a t i o n s o n v a r i a t i o n s in t h e m a l es ex ch a rac t e r s an d t h e i r r e l a t i o n t o t h e an d ro g en i c g l an d i n t h e s h r i mpMa cr o b r a ch iu m id a e (He l l e r ) . A c ta Zo o l . (S to ckh . ) , 5 4 , 1 9 3 - 2 0 0 .Wohl far th , G . (1977) . Shoo t carp . B a mid g eh , 2 9 , 3 5 - 9 .

malecha 1986 aquacultural-engineering

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