Marine Chemistry in the Coastal Environment - ACS Publications

30 Pioneering the New Industry of Shrimp Farming PAUL F. BENTE, JR.

Downloaded by UNIV OF SYDNEY on May 3, 2015 | http://pubs.acs.org Publication Date: June 1, 1975 | doi: 10.1021/bk-1975-0018.ch030

Marifarms, Inc., P.O. Box 2239, Panama City, Fla. 32401

,

I n t h e l a t e 1 9 3 0 s D r . M. F u j i n a g a (Hudinaga), working a t A i o , Japan, s t u d i e d t h e b i o l o g y and r e p r o d u c t i o n o f kuruma shrimp (Penaeus j a p o n i c u s ) caught c o m m e r c i a l l y i n t h e S e t o I n l a n d Sea. H i s c l a s s i c paper ( 1 ) , c o n t a i n i n g d e t a i l e d drawings and d e s c r i p t i o n s of"~the many l a r v a l t r a n s f o r m a t i o n s and complete b i o l o g i c a l development o f t h i s shrimp, was r e c e i v e d f o r p u b l i c a t i o n ( i n t h e E n g l i s h language) one week b e f o r e P e a r l Harbor day. Such r e s e a r c h , i n t e r r u p t e d b y t h e war, was resumed i n t h e 1950's. H a t c h i n g and r a i s i n g shrimp c o m m e r c i a l l y g o t underway i n t h e I960*s. The Japanese government a l s o i n s t a l l e d s e v e r a l large hatcheries with the goal o f h a t c h i n g baby shrimp i n o r d e r t o r e s t o c k t h e S e t o I n l a n d Sea t o improve commercial s h r i m p i n g . H a t c h i n g and growing shrimp became t h e most advanced o f some two-dozen m a r i c u l t u r e o p e r a t i o n s t h a t were under intense study i n Japan. Kuruma shrimp a r e now c u l t i v a t e d c o m m e r c i a l l y i n Japan i n many s m a l l farms, w h i c h have growing ponds t h a t g e n e r a l l y a r e from 2 t o 20 a c r e s i n s i z e . To h a r v e s t a c r o p , a pond i s d r a i n e d , and t h e shrimp a r e c o l l e c t e d b y hand, c h i l l e d , packed i n sawdust, s h i p p e d b y a i r , t r u c k o r t r a i n , and d e l i v e r e d a l i v e , t o tempura r e s t a u r a n t s . T h i s s p e c i a l t y market has grown t o about 700,000 l b s . p e r y e a r . I t s p r i c e s a r e s e v e r a l times h i g h e r t h a n t h o s e charged f o r p r o c e s s e d f r o z e n o r canned shrimp s o l d i n t h e w o r l d m a r k e t s . E f f o r t s were n o t made t o d e v e l o p t h e know-how i n t o l a r g e s c a l e f a r m i n g t o s u p p l y w o r l d markets, p r i m a r i l y b e c a u s e t h e r e were no s u i t a b l e , l a r g e , #

487

In Marine Chemistry in the Coastal Environment; Church, T.; ACS Symposium Series; American Chemical Society: Washington, DC, 1975.

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unused c o a s t a l areas a v a i l a b l e f o r such o p e r a t i o n s . Water p o l l u t i o n and u n f a v o r a b l y low temperatures f o r much o f the y e a r were o t h e r d e t e r r i n g f a c t o r s . M a r i f a r m s , I n c o r p o r a t e d , was formed t o u n d e r t a k e such a v e n t u r e i n the U n i t e d S t a t e s , s t a r t i n g i n F l o r i d a . With a p p r o v a l o f the Japanese government, M a r i f a r m s a c q u i r e d shrimp m a r i c u l t u r e r i g h t s and know-how from the T a i y o F i s h i n g Co., L t d . , o f Tokyo, J a p a n . To b e g i n e x p l o r a t o r y t e s t s i n 1968, Dr. M . Miyamura, t h e n p r e s i d e n t o f T a i y o s s u b s i d a r y engaged i n shrimp f a r m i n g a t Takematsu, came t o Panama C i t y , F l o r i d a , w i t h f o u r e x p e r i e n c e d t e c h n i c i a n s . Americans were a l s o employed t o u n d e r s t u d y and t o h e l p . As o p e r a t i o n s l a t e r expanded, a t o t a l o f 14 Japanese were employed a t one time o r another, b u t g r a d u a l l y a l l r e t u r n e d t o Japan, e x c e p t f o r Dr. Miyamura who s t i l l s e r v e s on the company s Board o f Directors.


1

1

I n t h i s p i o n e e r i n g work M a r i f a r m s encountered a f o r m i d a b l e a r r a y o f problems — b u s i n e s s , f i n a n c i a l , public relations, socio-cultural, technical, etc. T h i s paper d e s c r i b e s a few o f the many s i g n i f i c a n t t e c h n i c a l advances t h a t the company made i n w r e s t l i n g w i t h t h e p r o b l e m o f making l a r g e s c a l e o p e r a t i o n s viable. Hatching A l t h o u g h the Japanese team was v e r y e x p e r i e n c e d i n h a t c h i n g the kuruma shrimp, o f c o u r s e , i t had never worked w i t h the t h r e e commercial v a r i e t i e s found i n t h e G u l f o f Mexico — t h e brown (Penaeus a z t e c u s ) , the w h i t e (Penaeus s e t i f e r u s ) , and the p i n k (Penaeus duorarum) shrimp. Moreover, t h e r e was no a v a i l a b l e h a t c h i n g e x p e r i e n c e i n U.S. l a b o r a t o r i e s comparable t o t h a t i n Japan, and no e x p e r i e n c e i n c a t c h i n g l a r g e numbers o f shrimp, ready t o spawn. Hence, h a t c h i n g became the f i r s t o r d e r o f b u s i n e s s . H a t c h i n g i s f i r s t d e s c r i b e d and t h e r e a f t e r mother s h r i m p i n g , t h a t i s , p r o c u r i n g shrimp f o r spawning t o begin hatching. Three c o n c r e t e , 28,000 g a l l o n t a n k s , a p p r o x i m a t e l y 30 f t . b y 30 f t . by 6 f t . deep, the l a r g e s t s i z e t h a t had been used s u c c e s s f u l l y i n Japan, were



30.

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i n s t a l l e d f o r t h e h a t c h i n g t e s t s . A f t e r a few a b o r t i v e s t a r t s i n t h e summer o f 1968, the h a t c h e r y t u r n e d o u t 7.5 m i l l i o n baby shrimp o f the p i n k variety. I n 1969, about 14 m i l l i o n w h i t e , 5 m i l l i o n p i n k , and 70 thousand brown shrimp were h a t c h e d . F o r t u n a t e l y , the h a t c h i n g o f each v a r i e t y s u f f i c i e n t l y resembled t h e p r o c e s s f o r the kuruma shrimp t h a t the t e c h n i c i a n s were a b l e t o adapt p r o c e d u r e s t o a c h i e v e good y i e l d s . On t h e s t r e n g t h o f t h i s p r o g r e s s , 32 more o f these tanks were c o n s t r u c t e d f o r commercial work. D u r i n g t h e 1970-74 seasons i t t u r n e d o u t a t o t a l o f about 1.5 b i l l i o n baby shrimp. Each y e a r 20 m i l l i o n were s t o c k e d i n p u b l i c waters, and modest q u a n t i t i e s were p r o v i d e d t o s e v e r a l r e s e a r c h c e n t e r s . The h a t c h i n g o f baby shrimp i s shown b y T a b l e I . Table I C h a r a c t e r i s t i c s of Hatching Time i n Form Indicated (days)

Form

Egg Larva Nauplius (Stages I-V) Zoea (Stages I - I I I ) Mysis (Stages I - I I I ) Shrimp Baby (suspended i n water) Baby (bottom dwelling)

Cycle Size at Close of Period (mm.)

Common Food

0.25

1

0.5

2

egg

4

phytoplankton (5-10 μ i n s i z e ) zooplankton, artemia, yeast

2.2

artemia, p e l l e t feed

7.5

3

6

14

yolk

marine l i f e i n c l . benthic, p e l l e t feed

* Weight a t t h i s s i z e i s about 0.02

5.0

20.0*

gms.



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T h i s i s a f a s c i n a t i n g , complex p r o c e s s i n v o l v i n g 12 t r a n s f o r m a t i o n s a f t e r t h e s p a w n e d e g g s h a v e b e e n fertilized. T h e l i t e r a t u r e i s now r e p l e t e w i t h b i o l o g i c a l d e t a i l s o f these changes. Excellent descript i o n s a r e g i v e n i n t w o U.S. P a t e n t s (2) ( 3 ) , w h i c h have been d e d i c a t e d t o t h e p u b l i c . ~" ~~ T h i s paper i s concerned o n l y w i t h a few o f the procedures i n which m o d i f i c a t i o n s of commercial s i g n i f i c a n c e h a v e b e e n made. I n g e n e r a l , t h e h a t c h i n g w a t e r must be g e n t l y a e r a t e d . I t s h o u l d be a t 25°-28°C. a n d h a v e a s a l i n i t y o f a t l e a s t 14 p a r t s per thousand. I f s a l i n i t y i s low, i t can be i n c r e a s e d by a d d i t i o n o f rock s a l t r a t h e r than sea s a l t , a s i m p l e r , c h e a p e r p r o c e d u r e w h i c h t h e company d e v e l o p e d a s f l e x i b i l i t y i n o p e r a t i n g p r o c e d u r e s was explored. The z o e a d o e s n o t swim and must b e k e p t suspended i n w a t e r and f e d b y h a v i n g i t s mouth c o l l i d e w i t h p h y t o p l a n k t o n . The o r i g i n a l p r o c e s s involved culturing special phytoplankton (chlorella and Skeletonema costaturn) b y a d d i n g n u t r i e n t s , i n c l u d i n g r e s i d u e s o b t a i n e d from the manufacture o f soy sauce. One may j u d g e w h a t t h i s h a t c h i n g w a t e r l o o k e d l i k e from the f a c t t h a t the Japanese c a l l e d the m i x t u r e " b l a c k t e a . " T h i s p r o c e d u r e was g r a d u a l l y modified to culturing naturally occurring phytoplankt o n b y a d d i n g c h e m i c a l f e r t i l i z e r s as n u t r i e n t s t o enhance t h e i r m u l t i p l i c a t i o n . Y e a s t was a l s o a d d e d as a f o o d . T h e raysis s w i m s a f t e r i t s f o o d a n d l i v e s o n z o o p l a n k t o n and o t h e r m e a t . The o r i g i n a l p r o c e s s added v a r i o u s forms o f s u p p l e m e n t a l meat, s u c h as f i n e l y g r o u n d up c l a m s . T h i s was m o d i f i e d t o g r o u n d f i s h , a n d t h a t was l a t e r d i s p l a c e d b y a d d i t i o n s o f a l i v e f o o d , i n t h e f o r m o f h a t c h e d a r t e m i a , commonly c a l l e d b r i n e shrimp. These procedures s i m p l i f i e d o p e r a t i o n s , r e d u c e d l a b o r , and i m p r o v e d y i e l d s . In t h i s process the c a p a c i t y o f the h a t c h i n g tanks i s governed c h i e f l y by the t o t a l weight of l i v i n g shrimp (biomass) a t the time the shrimp are f i n a l l y moved t o t h e g r o w i n g a r e a s o f t h e f a r m . This v a r i e s f o r each v a r i e t y of shrimp. White shrimp can t o l e r a t e a much h i g h e r d e n s i t y t h a n b r o w n o r p i n k shrimp. Time f o r t h e f u l l h a t c h i n g c y c l e a l s o v a r i e s


30. BENTE

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and i s a n o t h e r l i m i t a t i o n on p r o d u c t i v i t y . are g i v e n i n Table I I .

Details

Table I I P r o d u c t i v i t y L i m i t s o f 28,000 G a l l o n H a t c h e r y Tanks


Kind o f Shrimp

Brown White Pink

Avg. L i m i t i n g Population*

1,250,000 4,000,000 2,000,000

S i z e o f Shrimp a t End o f C y c l e (mg.) 5-10 3-6 6-8

Duration o f T o t a l Cycle (days) 35-40 22 30

* O c c a s i o n a l l y under i d e a l c o n d i t i o n s d e n s i t i e s 2.5 times t h i s h i g h have been o b t a i n e d . The l i m i t i n g o r maximum number o f eggs o r l a r v a e t o s t a r t t h e p r o c e s s i s thus d e t e r m i n e d b y t h e s e f a c t s , t a k i n g i n t o a c c o u n t m o r t a l i t y e x p e c t e d as t h e l a r v a e move t h r o u g h t h e i r many t r a n s f o r m a t i o n s . To i n c r e a s e c a p a c i t y , t h e p r o c e s s has b e e n d i v i d e d i n t o two s t e p s , i n v o l v i n g s c a l e - u p o f an e x p l o r a t o r y l a b o r a t o r y r e s e a r c h p r o c e d u r e used b y C o r n e l i u s Mock and coworkers o f t h e U.S. G a l v e s t o n Laboratory. The f i r s t s t e p i s conducted i n a c y l i n d r i c a l , open t o p , 7000 g a l l o n , f i b e r - g l a s s tank s t a n d i n g on l e g s i n one c o r n e r o f the 28,000 g a l l o n concrete tank. I t i s p a r t i a l l y submerged i n t h e water o f t h e b i g t a n k . Water i n t h e c y l i n d r i c a l tank i s g e n t l y c i r c u l a t e d — b y b e i n g removed from t h e bottom i n t o an a i r l i f t p i p e which d i s c h a r g e s i t a t the t o p so as t o cause a s l o w r o t a r y s t i r r i n g m o t i o n o f the water column. T h i s o p e r a t i o n accomplishes s e v e r a l t h i n g s . The c i r c u l a t i o n p r e v e n t s the shrimp l a r v a e , food p a r t i c l e s , and g e n e r a l d e b r i s , s u c h as egg s h e l l s , from s e t t l i n g t o t h e bottom, a s i t u a t i o n which g e n e r a l l y k i l l s o f f a large proportion of a hatching i f i t i s allowed to p e r s i s t . To a v o i d t h a t i n t h e 28,000 g a l l o n t a n k s , t e c h n i c i a n s o c c a s i o n a l l y had t o swim about w i t h f l i p p e r s t o s t i r up t h e s e t t l i n g s accumul a t i n g on t h e bottom o f t h e tank d e s p i t e v i g o r o u s a i r



492

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agitation. The p r o c e d u r e a l s o a l l o w s t h e f i r s t p a r t o f t h e p r o c e s s t o b e d o n e i n much h i g h e r d e n s i t y , thus enhancing the larvae's capture o f the food p a r t i c l e s and t h e r e b y r e d u c i n g t h e t o t a l amount o f e x t r a feed required. I t turns out that this also increases t h e s u r v i v a l o f t h e l a r v a e as t h e y pass t h r o u g h t h e transformations. A t t h e a p p r o p r i a t e t i m e t h e 7000 g a l l o n t a n k i s d r a i n e d i n t o t h e 28,000 g a l l o n t a n k w h i c h c o n t a i n s water prepared f o r the second s t e p o f t h e h a t c h i n g c y c l e when t h e s h r i m p a r e i n t h e p o s t l a r v a l f o r m . While t h i s step i s being c a r r i e d out, i f desired, the f i r s t s t e p o f t h e n e x t h a t c h i n g c a n commence a n d r u n concurrently. Thus, once o p e r a t i o n s a r e underway, t h e number o f c y c l e s t h a t c a n b e t u r n e d o u t i s e s s e n t i a l l y doubled. S i n c e s u r v i v a l i s i n c r e a s e d , t h e new p r o c e d u r e i s c a p a b l e o f e s s e n t i a l l y d o u b l i n g and a t times even t r i p l i n g p r o d u c t i o n r a t e , w h i l e s i m u l t a n e o u s l y r e d u c i n g t h e amount o f f o o d u s e d p e r g i v e n number o f s h r i m p h a t c h e d . Though e v e r y t a n k i s g e n e r a l l y o p e r a t i n g i n a d i f f e r e n t s t a g e o f t h e comp l e x h a t c h i n g p r o c e s s , a l l t h i s i s done b y f o u r b i o l o g i s t s a n d t w o h e l p e r s who a r e d e p l o y e d t o o t h e r o p e r a t i o n s w h e n t h e h a t c h e r y i s s h u t down. With t h i s overview of the hatching process i n m i n d c o n s i d e r now some o f t h e d e v e l o p m e n t s i n p r o c u r i n g g r a v i d shrimp needed b y t h e h a t c h e r y . Mother

Shrimping

A f t e r h a t c h i n g was d e m o n s t r a t e d , t h e c o m p a n y made many e x p l o r a t o r y t r i p s , c h a r t e r i n g c o m m e r c i a l t r a w l e r s , t o l e a r n w h e r e i n t h e G u l f and when d u r i n g the calendar year each v a r i e t y o f shrimp i n the g r a v i d c o n d i t i o n c o u l d b e c a u g h t i n s u f f i c i e n t numbers t o operate commercially. G r a v i d shrimp are females c a r r y i n g roe s u f f i c i e n t l y developed so t h a t spawning can be induced i n a hatchery. F i s h i n g i s good when 5 p e r c e n t o r more o f a n o r m a l c a t c h a r e gravid. T h o u g h many s i t e s w e r e f o u n d w h e r e m o t h e r s h r i m p i n g c a n b e done s u c c e s s f u l l y , t h o s e most s u i t e d t o t h e company's l o c a t i o n a r e t h e w a t e r s o f f M o b i l e d u r i n g February through A p r i l f o r brown shrimp,



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A p p a l a c h i c o l a d u r i n g May and June f o r w h i t e shrimp, and b o t h l o c a t i o n s d u r i n g J u l y t h r o u g h September f o r p i n k shrimp. D u r i n g t h e seasons o f 1970 t h r o u g h 1974, the company p r o c u r e d a t o t a l o f 154,000 mother shrimp, e q u i v a l e n t t o about 13,000 pounds, heads on b a s i s . Mother s h r i m p i n g i n i t s e l f i s a h i g h l y t e c h n i c a l o p e r a t i o n , f o r which t h e crew must be s p e c i a l l y t r a i n e d and t h e t r a w l e r s p e c i a l l y equipped t o h o l d the shrimp a l i v e i n a e r a t e d , c h i l l e d water, and t h e n t o package and s h i p them s u c c e s s f u l l y t o t h e h a t c h e r y by c h a r t e r e d p l a n e o r , i f t h e r u n i s s h o r t , b y company truck. H a n d l i n g w h i t e mother shrimp poses a s p e c i a l problem. The sack o f sperm a c q u i r e d b y t h e mother shrimp d u r i n g c o p u l a t i o n i s c a r r i e d o u t s i d e t h e s h e l l . (Pink and brown mother shrimp c a r r y i t i n s i d e t h e shell.) I f t h e g r a v i d w h i t e shrimp becomes a g i t a t e d enough t o snap i t s t a i l , as i t does i n t r y i n g t o escape, i t g e n e r a l l y l o s e s t h e spermatophore making f e r t i l i z a t i o n o f t h e s u b s e q u e n t l y spawned eggs impossible. D e s p i t e such odds, b y c a r e f u l h a n d l i n g , t h e h a t c h i n g o f w h i t e shrimp was q u i t e s u c c e s s f u l . These odds were f i n a l l y r e d u c e d b y p l a c i n g each mother shrimp, as soon as i t was caught, i n t o a p e r f o r a t e d c y l i n d e r , capped on each end, and o f a d i a m e t e r t h a t p r e v e n t e d each shrimp from f l i p p i n g i t s t a i l . After t r a n s p o r t a t i o n t h e shrimp was r e l e a s e d s a f e l y i n t h e hatching tank. When a g r a v i d shrimp i s p l a c e d i n t h e h a t c h i n g tank, spawning a l m o s t i n v a r i a b l y t a k e s p l a c e d u r i n g the next n i g h t . S i n c e t h i s happens i n t h e d a r k , no one sees what goes on. By s p e c i a l t e c h n i q u e s , t h e Japanese government has c a p t u r e d t h e spawning p r o c e s s on movie f i l m . T h i s shows t h a t as t h e mother shrimp swims around i t r e l e a s e s a s t r e a m o f r o e t h a t i s d i s p e r s e d i n t h e water b y t h e g e n t l e p a d d l i n g a c t i o n o f i t s 10 swimmerets. The spawning a l s o r u p t u r e s t h e spermatophore s o t h a t t h e r e l e a s e d eggs a r e f e r t i l i z e d i n the sea water. F e e d i n g Shrimp

i n Growing

Areas

In Japan l i t t l e space was a v a i l a b l e f o r use as shrimp farms. T h e r e f o r e , t h e p a t t e r n o f development



494

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CHEMISTRY

t h e r e was t o c u l t i v a t e w h a t s p a c e was a v a i l a b l e a s i n t e n s i v e l y as p o s s i b l e . B e n t h i c foods, on which shrimp n o r m a l l y f e e d , d i d n o t grow n a t u r a l l y i n t h e bottoms o f t h e ponds t h a t were c o n s t r u c t e d , f o r t h e s e were g e n e r a l l y on a hard pan t h a t had been used i n t h e f o r m e r p r a c t i c e o f e v a p o r a t i n g s e a w a t e r t o manufacture salt. I n f a c t , sand u s u a l l y had t o be h a u l e d i n , i n order t o p r o v i d e a bottom i n which the shrimp c o u l d submerge t h e m s e l v e s . A t t h e t i m e M a r i f a r m s a c q u i r e d i t s know-how i t was common p r a c t i c e t o f e e d the shrimp c r u s h e d clams. M a r i f a r m s s e l e c t e d s i t e s where space p e r m i t t e d extensive operations. A 2 5 0 0 a c r e embayment w i t h t i d a l e x c h a n g e o f w a t e r was l e a s e d f r o m t h e S t a t e o f F l o r i d a a n d t w o 3 0 0 a c r e m a r i n e l a k e s w i t h pumped w a t e r exchange were c o n s t r u c t e d on uplands l e a s e d f r o m a p r i v a t e owner t o compare f a r m i n g i n e a c h t y p e of area. B o t h t y p e s o f farms had bottoms w h i c h were t y p i c a l l y s o f t and sandy and i n w h i c h b e n t h i c o r g a n isms abound. I t was i n t e n d e d t h a t t h e s h r i m p f e e d p a r t i a l l y on n a t u r a l l y o c c u r r i n g marine l i f e which w o u l d p r o v i d e s u f f i c i e n t g r o w t h s t i m u l a n t s and n u t r i e n t s t h a t they c o u l d be f e d a lower grade supp l e m e n t o f g r o u n d up t r a s h f i s h , s i n c e a h i g h e r q u a l i t y r a t i o n o f c l a m s was n o t a v a i l a b l e . L a b o r a t o r y t e s t s showed t h a t c o n v e r s i o n r a t i o s f o r a r a t i o n o f f i s h o n l y were v e r y h i g h , and t h a t o v e r a l l g r o w t h was s l o w a n d w o u l d p r o b a b l y n e v e r r e a c h f u l l p o t e n t i a l , r e g a r d l e s s o f how l o n g s h r i m p were f e d such a r a t i o n . B u t f i s h m e a t f e d i n comb i n a t i o n w i t h n a t u r a l l i v e food, or w i t h hatched a r t e m i a , g a v e much b e t t e r r e s u l t s . The company i n s t a l l e d a n i n s u l a t e d r e f r i g e r a t e d barge t o hold a supply o f f i s h . Pogy f i s h i n g b o a t s d e l i v e r e d l o a d s o f f i s h e v e r y week o r two, pumping as much a s 90 t o n s a t a t i m e i n t o t h e b a r g e . The f i s h w e r e pumped o u t a s n e e d e d , p a s s e d t h r o u g h a g r i n d e r t o make a s l u r r y t h a t was t r a n s p o r t e d t o t h e g r o w i n g a r e a s and d i s c h a r g e d i n t o t h e p r o p wash t o f e e d t h e s h r i m p as t h e f e e d - b o a t t o u r e d t h e s h r i m p f a r m i n a cross-grid pattern. D u r i n g 1 9 7 0 , t h e company f e d a t o t a l o f 800,000 l b s . o f raw f i s h . Because weather i n t e r f e r r e d w i t h f i s h i n g and d e l i v e r y when n e e d e d ,



30.

BENTE

Shrimp Farming

495

i t was d i f f i c u l t t o m a i n t a i n s t e a d y o p e r a t i o n s . F u r t h e r , i t was a messy, malodorous o p e r a t i o n , c o n d u c t e d under the t h r e a t o f b e i n g o v e r t a k e n by spoilage. T h e r e f o r e , the company sought a b e t t e r and more r e l i a b l e s u p p l e m e n t a l f e e d and abandoned the f e e d i n g o f raw f i s h i n 1971 when i t s e x p e r i m e n t a l work w i t h d r y feeds showed p r o m i s e . Many d r y feeds were t e s t e d , made from v a r i o u s c o m b i n a t i o n s o f i n g r e d i e n t s , u s i n g v a r i o u s b i n d e r s i n the c o n v e n t i o n a l method o f f e e d p r e p a r a t i o n by p r e s s i n g the m i x t u r e i n t o a mold. I n g e n e r a l the formula f o r p e l l e t i z e d shrimp f e e d , on a w e i g h t b a s i s , i s : 30% f i s h meal, 24% shrimp meal o r c r a b meal o r c o m b i n a t i o n s t h e r e o f , 20% soy meal, 20% meat s c r a p s , 2% whey, 2% v i t a m i n mix, and 2% b i n d e r such as Durabond. A l o c a l f e e d m i l l produced f o u r m i l l i o n pounds o f such p e l l e t s f o r o p e r a t i o n s d u r i n g 1971-73, b u t a l l f o r m u l a t i o n s had the d i s a d v a n t a g e o f d i s i n t e g r a t i n g i n sea water i n s e v e r a l m i n u t e s . T h i s o b s t a c l e was f i n a l l y overcome by R a l s t o n - P u r i n a by u s i n g the cooking-extrusion process. Their proprietary pellets had much b e t t e r c o h e s i v e p r o p e r t i e s ; a f t e r b e i n g dropped i n t o water t h e y d i d not d i s i n t e g r a t e f o r 20 t o 24 h o u r s , a l l o w i n g t h e shrimp adequate time t o f i n d and e a t the p e l l e t s . I n 1974, 2.2 m i l l i o n pounds o f t h e s e p e l l e t s were u s e d . L a s t y e a r , i n two 300 a c r e p r o d u c t i o n u n i t s y i e l d i n g h a r v e s t s o f 300 and 200 thousand pounds o f shrimp, r e s p e c t i v e l y , the c o n v e r s i o n r a t i o u s i n g t h i s p e l l e t f e e d was 1.8 and 1.9 pounds (dry weight) f e d p e r pound o f whole shrimp l a n d e d . I n d i c a t i o n s are t h a t c o n v e r s i o n r a t i o s as low as 1.4 w i l l be p o s s i b l e i n r a i s i n g shrimp o f a s i z e a v e r a g i n g 50 p e r pound, heads on b a s i s . I t i s i n t e r e s t i n g t o note t h a t i n J a p a n p r o p r i e t a r y d r y p e l l e t feeds o f a d i f f e r e n t c o m p o s i t i o n were s i m u l t a n e o u s l y and i n d e p e n d e n t l y d e v e l o p e d and adopted as s t a n d a r d p r o c e d u r e . The i n d u s t r y was d r i v e n t o t h i s by the growing s h o r t a g e and r i s i n g p r i c e s o f c l a m s . The p e l l e t s d e v e l o p e d i n J a p a n were b a s e d on h i g h e r q u a l i t y i n g r e d i e n t s , s i n c e the r a t i o n had t o p r o v i d e a l l the growth s t i m u l a n t s i n v i e w o f the f a c t t h a t n a t u r a l foods d i d not o c c u r i n the ponds


496

MARINE

CHEMISTRY

used i n Japan. Consequently, the c o s t o f such feed was v e r y much h i g h e r . N e v e r t h e l e s s , M a r i f a r m s p u r chased a l a r g e l o t o f t h i s f e e d and e v a l u a t e d i t . Used under M a r i f a r m s c o n d i t i o n s o f h a v i n g a p a r t i a l s u p p l y o f n a t u r a l f o o d a v a i l a b l e , t h e r e s u l t s were about the same as t h o s e o b t a i n e d u s i n g the f e e d d e v e l o p e d a t M a r i f a r m s , b u t , o f c o u r s e , the expense was f a r g r e a t e r . 1


C o n f i n i n g Shrimp t o the Growing A r e a s In f a r m i n g t i d a l w a t e r s , t h e baby shrimp were i n i t i a l l y p l a n t e d i n c i r c u l a r pens e n c l o s e d b y f i n e mesh n y l o n n e t s h a v i n g openings about l i k e t h a t o f window s c r e e n i n g . A c h a i n f a s t e n e d t o one edge o f t h e n e t s e a l e d o f f the bottom, w h i l e a l i n e o f c o r k f l o a t s a t t h e o t h e r edge h e l d the n e t t o t h e s u r f a c e . S i n c e s m a l l shrimp move about much as do suspended p a r t i c l e s i n r i l e d water, i n rough weather t h e shrimp would sometimes be washed o u t w i t h waves b r e a k i n g o v e r t h e t o p o f the pens. Though s t i l l on the farm, t h e s e l i b e r a t e d shrimp were i n an a r e a where p r e d a t o r s had not b e e n removed and where f e e d was n o t added. T h e r e f o r e , s u r v i v a l was low, and growth somewhat s l o w e r a t l e a s t u n t i l t h e shrimp grew l a r g e enough t o move about i n s e a r c h o f f o o d . Such d i f f i c u l t i e s were n o t e x p e r i e n c e d i n the marine l a k e s . Moreover, growth o f n a t u r a l foods i n c l o s e d systems c o u l d be s t i m u l a t e d by f e r t i l i z i n g the waters. Hence, o p e r a t i o n s i n the bay were improved b y c o n s t r u c t i n g s t a r t i n g ponds on the a d j a c e n t s h o r e . The p r o c e d u r e s used t o e n r i c h t h e n a t u r a l foods i n t h e s e pond w a t e r s , w h i l e a t the same time s u p p r e s s i n g u n d e s i r a b l e organisms, a r e t h o s e d e v e l o p e d b y Texas P a r k s W i l d l i f e Department ( 4 ) . I n a d d i t i o n a s u p p l e ment o f powdered p e l l e t f e e d i s s p r e a d on t h e waters f o r t h e baby shrimp. M a r i f a r m s conducted many t e s t s t o determine the s i z e t h a t shrimp must be t o be r e t a i n e d by n e t s o f v a r i o u s mesh s i z e s — o r s t r e t c h , as openings a r e termed by the f i s h i n g i n d u s t r y . M a r i f a r m s has found i t most p r o d u c t i v e t o r e t a i n baby shrimp b e h i n d pen n e t s o r w i t h i n d i k e d ponds u n t i l t h e y a r e a t l e a s t 0.3 gm i n s i z e . P o p u l a t i o n has t o be a d j u s t e d a t the



30.

BENTE

Shrimp Farming

497

o u t s e t so t h a t the shrimp do n o t exceed t h e p e r m i s s i b l e b i o - d e n s i t y under t h e o p e r a t i n g c o n d i t i o n s t h a t are e n c o u n t e r e d ( r a t e o f water exchange, temperature, oxygen s u p p l y , k i n d o f shrimp, c o n d i t i o n o f the bottoms, e t c . ) . When t h e shrimp become 0.3 gm i n s i z e t h e y a r e r e l e a s e d i n t o a much l a r g e r n u r s e r y e n c l o s e d b y a c o a r s e r n e t d e s i g n e d t o r e s t r a i n shrimp o f t h a t s i z e . Openings i n t h i s n e t a r e a p p r o x i m a t e l y 1/4" χ 1/4" (or 1/2" nominal s t r e t c h ) . By t h e time t h e shrimp exceed 0.8 gm i n s i z e , t h e y a r e r e l e a s e d i n t o s t i l l l a r g e r a d j a c e n t growing a r e a s c o n f i n e d b y a s t i l l c o a r s e r net s i z e d t o hold back these shrimp. This net has o p e n i n g s o f 5/16" χ 6/16" (or 21/32" nominal s t r e t c h ) . A f t e r the shrimp r e a c h 3.0 gm i n s i z e t h e y are r e l e a s e d i n t o the f i n a l growing a r e a which i s e n c l o s e d b y a n e t w i t h openings 7/16" χ 7/16" (or 7/8" nominal s t r e t c h ) . Shrimp behave v e r y d i f f e r e n t l y i n l a r g e growing a r e a s t h a n i n s m a l l e x p e r i m e n t a l ponds o f b u t a few a c r e s . White shrimp m i g r a t e i n s c h o o l s ? whereas brown and p i n k do n o t . Shrimp a l s o move t o f i n d n a t u r a l f e e d i n g g r o u n d s . As shrimp grow l a r g e r t h e y seek deeper water, b u t t h e y f r e q u e n t l y move back i n t o warm s h a l l o w waters t o f e e d on n a t u r a l foods t h a t seem t o abound where more s u n l i g h t r e a c h e s the bottoms. They g e n e r a l l y do not seek t o escape u n t i l t h e y a r e young a d u l t s , a t which time t h e y would norm a l l y move out t o sea w i t h t h e t i d e s . T h i s tendency o c c u r s j u s t p r i o r t o and d u r i n g h a r v e s t p e r i o d s . At s u c h times M a r i f a r m s a t t a c h e s a s p e c i a l l y d e s i g n e d supplementary c o l l a r o f f l o a t s t o the top o f i t s nets i n o r d e r t o s t o p t h e shrimp from swimming o v e r the top d u r i n g rough weather. M a r i f a r m s uses some 15 m i l e s o f n e t s . The h y d r o dynamics o f c o n s t r u c t i o n may be compared t o c o n s t r u c t i n g a suspension cable that i s subjected to f l u c t u a t i n g heavy l o a d s , i . e . , t i d e s moving back and forth. To h o l d t h e n e t s down on t h e bottom, a heavy c h a i n i s l a s h e d t o t h e n e t . V a r i o u s head r o p e s on which f l o a t s were p l a c e d have been t r i e d t o h o l d the net up t o the s u r f a c e . A l l t h e p l a s t i c t y p e r o p e s have caused t r o u b l e , b e c a u s e t h e y g r a d u a l l y e l o n g a t e permanently w i t h repeated s t r e t c h i n g by the t i d e s .


498

MARINE CHEMISTRY

The r e s u l t i s t h a t t h e n e t a t t h e top i s g r a d u a l l y s t r e t c h e d o u t , though not a t the bottom, u n t i l i t f i n a l l y t e a r s from top t o bottom. T h i s d i f f i c u l t y has now been overcome by u s i n g p l a s t i c c o a t e d g a l v a n i z e d s t e e l c a b l e s i n p l a c e o f head r o p e s . Nets o f t e n used i n t h e f i s h i n g i n d u s t r y do n o t have a b a l a n c e d c o n s t r u c t i o n — that i s a heavier n y l o n c o r d i s used i n one d i r e c t i o n t h a n i n t h e other. In Marifarms use when such n e t s t e a r , t h e y p a r t as i f b e i n g u n z i p p e r e d , b r e a k i n g the weaker s t r a n d s progrès s i v e l y and r a p i d l y . M a r i f a r m s has had i t s n e t s s p e c i a l l y made i n a b a l a n c e d c o n s t r u c t i o n . No m a t t e r what s i z e openings a r e used, the company has found, t h a t t o be s t r o n g enough, the n e t s must have a t l e a s t a pound o f n y l o n f o r e v e r y 25-30 s q . f t . of net. Nets a r e d i p p e d i n a p r o p r i e t a r y a n t i f o u l i n g m i x t u r e t o r e d u c e t h e i r p i c k i n g up b a r n a c l e s , h y d r o i d s , and o t h e r marine g r o w t h s . The d i p i s made up o f 84% copper o x i d e , 8% t r i b u t y l t i n , and 8% t r i p h e n y l t i n dispersed i n petroleum d i s t i l l a t e . I n a d d i t i o n n e t s must be washed e v e r y few days b y pumping many heavy j e t s o f water, under water, onto each s i d e o f t h e n e t . Equipment f o r d o i n g t h i s i s suspended from a b a r g e on w h i c h a r e l o c a t e d two pumps. T h i s i s one o f t h e " t r a c t o r s " o f the farm which had t o be d e v e l o p e d . I t t r a v e r s e s the n e t s from one end t o t h e o t h e r . A n o t h e r " t r a c t o r " o f the farm i s equipped w i t h a p a i r o f l a r g e r o t a t i n g n y l o n b r i s t l e b r u s h e s w h i c h can s c r u b t h e n e t s c l e a n i f more v i g o r o u s a c t i o n i s n e c e s s a r y . I n appearance t h e s e b r u s h e s l o o k l i k e t h e ones you see i n a c a r wash l i n e , b u t t h e y a r e much s t i f f e r . Without p e r i o d i c c l e a n i n g , t h e openings o f the n e t become so p l u g g e d t h a t the n e t s b r e a k under the s t r a i n o f heavy tides. A n o t h e r b a r g e t r a c t o r has b e e n d e v e l o p e d t o d e p l o y n e t s t o e n c l o s e a r e a s f o r shrimp f a r m i n g o p e r a t i o n s and t o s e t up o u t e r n e t s t o keep o u t f i s h . T h i s t r a c t o r can p u t o u t a m i l e o f n e t i n one day. The same b a r g e can remove the n e t s and t h e c h a i n w h i c h h o l d s the n e t s t o t h e b o t t o m . E v e r y w i n t e r a f t e r h a r v e s t i n g has been completed, t h e s e removal o p e r a t i o n s a r e done i n two s e p a r a t e s t e p s , f i r s t


1


30. BENTE

Shrimp Farming

499

removing f l o a t s and n e t , and t h e n c h a i n which has been c u t f r e e . The n e t s a r e c l e a n e d , r e p a i r e d , c o a t e d w i t h a n t i f o u l i n g agents, r e b u i l t w i t h c h a i n and f l o a t l i n e , and p u t o u t f o r use a g a i n i n t h e spring. With p r o p e r c a r e , a n e t c a n be used f o r three years.


Multiple

Cropping

M a r i f a r m s has l e a r n e d enough about t h e a v a i l a b i l i t y o f mother shrimp and t h e h a t c h i n g and growing p a t t e r n s t o make i t p r a c t i c a l t o grow two c o n s e c u t i v e c r o p s o f shrimp i n t h e v e r y same a r e a s . The f i r s t c r o p i s brown shrimp. These a r e hatched i n F e b r u a r y and March, p l a n t e d i n t h e s t a r t i n g a r e a s i n A p r i l and May, moved p r o g r e s s i v e l y t h r o u g h t h e n u r s e r y and i n t o the grow-out a r e a s , and h a r v e s t e d i n June t o A u g u s t . The h a t c h e r y meanwhile s h i f t s t o w h i t e shrimp, w h i c h a r e hatched i n t h e May and June p e r i o d . These move p r o g r e s s i v e l y through t h e same a r e a s a r r i v i n g i n the grow-out a r e a s a f t e r the summer h a r v e s t o f brown shrimp has been completed. The w h i t e shrimp a r e t h e n h a r v e s t e d i n t h e O c t o b e r - December p e r i o d . While i t i s t h e o r e t i c a l l y p o s s i b l e t o r u n a t h i r d c r o p o f p i n k shrimp t h r o u g h t h e system, h a t c h i n g t h e s e i n July-August-September period, holding t h r o u g h t h e w i n t e r i n j u v e n i l e form w h i l e i t i s t o o c o l d f o r growth t o c o n t i n u e , and s u b s e q u e n t l y cont i n u i n g growth i n t h e s p r i n g and h a r v e s t i n g them t o g e t h e r w i t h t h e brown c r o p d u r i n g t h e next summer, t e s t s show t h a t w i n t e r i n g o v e r o p e r a t i o n s s h o u l d have f a i r l y deep h o l d i n g a r e a s so t h a t t h e water d o e s n ' t c o o l down as much as i t does i n s h a l l o w e r a r e a s d u r i n g c o l d snaps. S u r v i v a l i n t h e s h a l l o w pond a r e a s i n p a r t i c u l a r i s t o o low t o j u s t i f y such e f f o r t s . When water temp e r a t u r e drops below 1 0 C , s u r v i v a l f a l l s o f f markedly. A t 4°C. the e f f e c t i s l e t h a l . Operations f u r t h e r s o u t h ought t o make a t h i r d c r o p f e a s i b l e . Ô

Harvesting Procedures In hand.

for Quality

Product

shrimping a t sea, the c a t c h i s manipulated by Sometimes as l i t t l e as 10 p e r c e n t o f what i s



500

MARINE

CHEMISTRY

caught a r e shrimp. F i r s t o f a l l , the t r a s h f i s h and o t h e r marine l i f e a r e s o r t e d out by hand and thrown o v e r b o a r d . Then w h i l e t r a w l i n g c o n t i n u e s , the crew members squeeze t h e heads o f f the shrimp b y hand, p l a c e the t a i l s i n w i r e b a s k e t s , and f i n a l l y s t o r e t h e s e w i t h i c e below deck. When a l o a d i s accumul a t e d , the t r a w l e r r e t u r n s t o p o r t t o u n l o a d and s t o c k up on p r o v i s i o n s , and t h e n r e t u r n s t o f i s h i n g a t s e a . S h i p s s t a y o u t a week o r more a t a t i m e . By c o n t r a s t , M a r i f a r m s uses s i m i l a r t r a w l e r s , b u t s i n c e t h e farmed b a y waters c o n t a i n l i t t l e b u t shrimp, t h e r e i s no need t o s o r t the c a t c h by hand on deck. The c a t c h i s dropped on deck, s p r e a d o u t and l a y e r e d w i t h shaved i c e . D u r i n g t r a w l i n g the c a t c h i s g e n e r a l l y k e p t c o v e r e d by a c a n v a s . A f t e r a few hours o f t r a w l i n g , the b o a t has a l o a d o f s e v e r a l thousand pounds on i t s s t e r n deck. Then t h e b o a t r e t u r n s t o a dock a t s h o r e on the farm where the c a t c h i s unloaded b y a vacuum l i f t w i t h the a i d o f a heavy s t r e a m o f w a t e r . In t h e p r o c e d u r e used i n h a r v e s t i n g t h e farmed marine l a k e s , as t h e y a r e caught, the shrimp a r e p l a c e d i n t o a t r a n s f e r n e t on the s p e c i a l s k i f f used f o r the t r a w l i n g . E v e r y hour o r so t h e s k i f f s t o p s a t a d o c k i n g p o i n t so t h a t t h e t r a n s f e r n e t can be l i f t e d out and i m m e d i a t e l y emptied i n t o a tank o f i c e water mounted on a t r a i l e r . E v e r y few hours t h i s i s h a u l e d t o a vacuum l i f t f o r f i n a l u n l o a d i n g . The shrimp a r e d i s c h a r g e d from the l i f t i n t o a l a r g e a g i t a t e d tank o f i c e water from which t h e y a r e removed b y a m e t a l c h a i n l i n k t y p e conveyor b e l t . The shrimp on t h e conveyor p a s s a c r o s s an i n s p e c t i o n t a b l e where d e b r i s , and the r e l a t i v e l y few f i s h , c r a b s , e t c . , a r e removed by hand. (The c r a b s a r e accumulated and s o l d as a b y - p r o d u c t . Crab y i e l d i n 1974 was about 20,000 l b s . , l i v e weight.) A t t h e end o f the conveyor the shrimp a r e weighed i n t o s t a n d a r d f i s h boxes h o l d i n g 100 pounds e a c h . They a r e k e p t c h i l l e d b y p l a c i n g a l a y e r o f i c e on t h e bottom, i n the m i d d l e , and on the t o p o f each box o f shrimp. These boxes a r e l o a d e d i n t o a t r a c t o r t r a i l e r , and l o a d s o f 20,000 t o 30,000 pounds a r e h a u l e d o f f t o nearby p r o c e s s i n g p l a n t s w i t h i n a day o f b e i n g caught.


30. BENTE

Shrimp Farming

501

The shrimp a r e d e l i v e r e d untouched b y human hands. C o n s e q u e n t l y , t h e b a c t e r i a count i s low. The shrimp do n o t g i v e o f f a s t r o n g f i s h y s m e l l when cooked. They have a sweet t a s t e , d e v o i d o f t h e i o d i n e - l i k e f l a v o r o f t e n e n c o u n t e r e d i n o t h e r shrimp. Thus, t h e q u a l i t y o f the c u l t i v a t e d shrimp produced by M a r i f a r m s i s s u p e r i o r t o t h e s t a n d a r d p r o d u c t o f the market p l a c e .


Outlook S i n c e 1970, t h e w o r l d c a t c h o f f i s h has d e c l i n e d . D e s p i t e g r e a t e r e f f o r t s and improved equipment and l a r g e r amounts o f f u e l b e i n g used, t h e c a t c h o f shrimp seems t o be r e a c h i n g a p l a t e a u . I n t h i s p e r i o d o f mounting c o n c e r n f o r p r o d u c i n g h i g h q u a l i t y , n u t r i t i o u s foods w h i l e a t t h e same time c o n s e r v i n g f u e l , i t i s i m p o r t a n t t o c o n s i d e r where shrimp m a r i c u l t u r e f i t s i n t o t h e p i c t u r e as food and f u e l consumption a r e compared f o r p r o d u c i n g v a r i o u s animals f o r f o o d . As T a b l e I I I shows, c u l t i v a t i n g shrimp uses much l e s s f e e d t h a n does r a i s i n g c a t t l e f o r b e e f . I t i s a l s o c o n s i d e r a b l y lower than f e e d consumed i n r a i s i n g hogs o r t u r k e y s , and i n f a c t i t f a l l s s l i g h t l y below t h a t needed t o r a i s e c h i c k e n s . The p e r c e n t a g e o f meat o b t a i n e d from whole shrimp i s a l s o h i g h e r t h a n t h a t o b t a i n e d from many a n i m a l s r a i s e d f o r f o o d . I t i s a l s o worth n o t i n g t h a t i n t h e c a s e o f r a i s i n g b e e f i t t a k e s about 960 days from s u c c e s s f u l f e r t i l i z a t i o n t o f i n a l s l a u g h t e r and i n t h e case o f p r o d u c i n g p o r k i t t a k e s 240 d a y s . However, i n t h e c a s e o f c u l t i v a t i n g shrimp, depending on v a r i e t y and season, i t t a k e s o n l y 120 t o 180 days, from day o f spawning t o day o f h a r v e s t . The d i r e c t and i n d i r e c t consumption o f f u e l i n shrimp m a r i c u l t u r e i s p r e s e n t l y about e q u a l t o t h a t f o r b e e f p r o d u c t i o n . However, when t h e m a r i c u l t u r e o p e r a t i o n s r e a c h normal c a p a c i t y , f u e l consumption w i l l f a l l t o h a l f t h a t needed t o r a i s e b e e f , and t o l e s s t h a n one f o u r t h t h a t needed t o c a t c h an e q u i v a l e n t amount o f shrimp a t s e a . Hence, development o f shrimp m a r i c u l t u r e i s i n k e e p i n g w i t h t h e demands and c o n c e r n s o f t h e time f o r c o n s e r v a t i o n i n the use o f


502

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f u e l and f o r more e f f i c i e n t use o f g r a i n s i n produci n g meat f o r human consumption. Table I I I Consumption o f C o m p e t i t i v e Feeds i n R a i s i n g A n i m a l s f o r Meat


L b s . Feed Consumed Per Animal 2,625 (a)

Cattle Swine Turkey Chicken Shrimp i n 1974 Shrimp projected

840 70 8 550,000 ( i )

L b s . Raw Lean Meat Produced

Conversion Ratio C o l 2/Col 3

b

7.75< ) (38.6)< > 9.9 5.8 3.8 3.55

340 ( ) (68) 85 < > l (f) (g) e

2

2 < 1

152,500

c

d

2.8

(a) I n a d d i t i o n t o 10,875 l b s . o f f o r a g e . (b) S l a u g h t e r w e i g h t = 1050 l b s . Grade i s " h i g h good" t o " l o w - c h o i c e " . " C h o i c e " and "prime" r e q u i r e f e e d i n g more g r a i n . (c) F o r a g e e x c l u d e d from c a l c u l a t i o n . F o r a g e above a c c o u n t s f o r 2 72 l b s . o f l e a n meat, g i v i n g a c o n v e r s i o n r a t i o o f 40 t o 1. (d) G r a i n a l o n e a c c o u n t s f o r 68 l b s . o f l e a n meat, g i v i n g c o n v e r s i o n r a t i o o f 38.6 t o 1. (e) S l a u g h t e r w e i g h t = 240 l b s . (f) S l a u g h t e r weight = 20 l b s . (g) S l a u g h t e r weight = 4 l b s . (h) Gross weight o f c r o p = 305,000 l b s . , heads on. ( i ) I n the c a s e o f shrimp, t h i s f e e d s u p p l i e d f o r a m a r i c u l t u r e c r o p o f 21 m i l l i o n shrimp, a v e r a g i n g about 70 p e r pound, heads on b a s i s . I n a l l , M a r i f a r m s has expended o v e r 310 man y e a r s o f e f f o r t i n p i o n e e r i n g shrimp f a r m i n g . To d a t e , t h e company has h a r v e s t e d 2 m i l l i o n pounds o f shrimp (about 140 m i l l i o n s h r i m p ) , 825,000 pounds (65 m i l l i o n ) o f t h i s l a s t y e a r . The g o a l s a r e t o



30. BENTE

Shrimp Farming

503

more t h a n double t h i s i n 1975. The c a p a c i t y o f t h e farm i s e x p e c t e d t o b e about 5 m i l l i o n pounds p e r y e a r , based on two c r o p s p e r y e a r r a i s e d d u r i n g an 8-month p e r i o d . Marifarms c o n s i d e r s t h i s o n l y t h e beginning. I n another decade shrimp f a r m i n g has t h e p r o s p e c t o f i n c r e a s i n g about 100 f o l d . I t can spread t o d e v e l o p i n g c o u n t r i e s where a new s o u r c e o f food and a c a s h c r o p s h o u l d b e welcome. I n t e c h n i q u e s , m a r i c u l t u r e o f shrimp s t a n d s a t t h e t h r e s h o l d where a g r i c u l t u r e was one o r two g e n e r a t i o n s ago. B u t m a r i c u l t u r e o f shrimp w i l l grow r a p i d l y w i t h t h e advantages o f today's know-how i n marine b i o l o g y coupled with a v a i l a b i l i t y o f e s s e n t i a l m a t e r i a l s , t e c h n o l o g y , and e n g i n e e r i n g .

Abstract Commercial scale procedures are described which have been developed in pioneering the new industry of hatching, growing and harvesting shrimp in netted off tidal areas and in diked marine lakes with pumped water exchange. The technology described is a fusion of Japanese and U.S. developments in marine biology extended by a 7-year (310 man year) endeavor to commercialize shrimp farming. To date, harvests at the Panama City, Florida, farm have landed approximately 140 million shrimp, weighing nearly 2 million pounds, heads-on basis. Sequential steps in the hatching and growing operations are reviewed. Development of pelleted, dry feeds to supplement live food naturally available in the sea water is discussed, and conversion ratios are given. Unique harvesting procedures are also described which result in a product that is superior in quality to that generally available in commercial quantities. Literature

Cited

1.

Hudinaga, M. (No. 2), pp.

Japanese 305-393.

Journal

of Zoology

2.

Miyamura, M. U.S. Patent No. 3,473,509, to Marifarms, Incorporated, dedicated to public. (October 21, 1969).

(1942),

assigned the


504

MARINE CHEMISTRY

3.

Motosaku, M. U.S. Patent No. 3,477,406, to Marifarms, Incorporated, dedicated to public. (November 11, 1969).

4.

Texas Parks Wildlife Dept. Research, Project 2-169-R,

assigned the

Salt Water Pond Austin, Texas.


Acknowledgement The author extends credit for the progress reported in this paper to all the employees of Marifarms. Their combined, sustained efforts in the face of many unexpected difficulties made this pioneering accomplishment possible.


Marine Chemistry in the Coastal Environment - ACS Publications

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