wickins 1987 aquacultural-engineering

7/28/2019 Wickins 1987 Aquacultural-Engineering

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Aqua cultural E ngineering6 (1987) 277-288

Fo od D i s tr ibut ion E qu ipm ent for Ind iv idua l ly -housedJ u v e n i le L o b s t e r s (Homarus pp.)J . F . W i c k i n s , E . J o n e s , T . W . B e a r d a n d D . B . E d w a r d s

Ministry of Agriculture, Fisheries and Food, Directorate of Fisheries Research,Fisheries Laboratory, Conwy, Gwynedd 1~l.q2 8UB, UK

A B S T R A C TT h e c o n s t r u c ti o n a n d o p e r a ti o n o f tw o s i m p l e m e c h a n i c a l fe e d er s , o n e f o ru s e w i t h d r y p e l le t s, t h e o t h e r w i t h a s u s p e n s i o n o f m y s i d s h r i m p s i n s e a -w a t e r, a r e d e s c r ib e d . B o t h f e e d e r s w e r e d e s i g n e d t o f a c i l i ta t e t h e f e e d i n g o fl ar g e n u m b e r s o f in d i v i d u a l l y - h o u s e d c r u s ta c e a n s h e l d i n l a b o r a t o r y a n dn u r s e ~ w a t e r t a b le s y s te m s .

T h e d r y f e e d e r d e l iv e r e d b e t w e e n 2 a n d 6 p e l l e ts t o 9 1 % o f t h e i n d i v i-d u a l c o m p o r t m e n t s w i t h le s s t h a n 2 % r e c e i v in g n o f o o d . T h e w e t f e e d e rd e l i v e r e d b e t w e e n 3 a n d 9 m y s i d s t o 7 3% o f t h e c o m p a r t m e n t s w i t h 2 "1 %r e ce iv in g n o f o o d . T h e d i s tr i b u ti o n o f e m p t y c o m p a r t m e n t s w a s r a n d o ms o t h a t it w a s u n li k e l y t h a t th e s a m e a n i m a l s w o u l d g o w i t h o u t f o o d a f te rt w o s u c c e s s i v e f e e d s .

I N T R O D U C T I O NTh e cul ture of juveni le lobsters ( H o m a r u s spp.) e i ther for s tock enha nce -ment t r ia ls (Wickins , 1983) or to produce market s ized animals (T.V.A.,1978 ; Bea rd e t a L , 1985 ) usual ly involves individual confinem ent to pre-vent f ight ing and canniba l i sm. Severa l conta inment methods have beenproposed for the cul ture of aggress ive or t e r r i tor ia l c rus taceans (VanOls t e t a l . , 1977; Micke l sen e t a l . , 1978; Richards and Wickins , 1979;Conkl in e t a L , 1981) but when la rge numbers of lobs te rs a re cu l tured ,feeding takes a cons iderable am oun t of s ta f f t ime or necess i ta tes thedevelopment of sophis t i ca ted and expens ive feeding equipment (Chap-man, 1983) .

Dry pe l le ted feeds a re more amenable to d i s t r ibut ion throughmechanica l feeders than a re mois t or f resh feeds but pe l le ted ra t ionsc la imed to be cap able of suppor t ing go od g rowth an d survival have onlyrecently been form ula ted (Co nkl in e t a l . , 1983) .277 Crown Copyright, 1987


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2 7 8 J . F . W i c k i n s, E . J o n e s, T . W . Be a r d a n d D . B . Ed w a r d sD u r i n g t h e p r o d u c t i o n o f j u v e n i l e l o b s te r s f o r s to c k e n h a n c e m e n tt ri a ls we r eq u i r ed r ap id m e tho ds fo r t he even d i s t r i bu t ion o f (a ) pe l l e ts

a n d (b ) f r e s h ly - t h a w e d m y s i d s h r i m p s N e o m y s i s i n t e g e r , ( 5 - 1 2 m m t o t a ll eng th ) t o ba t che s o f up to 10 000 juven i l es . T he dev ices had to ensu red e l iv e r y o f a b o u t 4 - 6 p i e c es o f f o o d t o e a c h r e a r in g c o m p a r t m e n t w i th -o u t t h e n e e d t o r e m o v e t h e c o m p a r t m e n t f r o m t h e r e a ri n g tr o u g hs .T h i s p a p e r d e s c r i b e s t h e c o n s t r u c t i o n a n d o p e r a t i o n o f t w o s i m p l em echa n ica l f eede r s , one fo r u se w i th d ry pe l le t s, the o the r fo r a suspen-s ion o f mys id sh r imps in s eawa te r . Bo th a r e su i t ab l e fo r app l i ca t ion tol a b o r a t o r y ' w a t e r t a b l e ' (C o n k l i n e t a l . , 1 9 8 1 ; M a l e c h a e t a l . , 1984) o r' sh a l lo w t r o u g h ' ( R i c h a r d s a n d W i c k in s , 1 9 7 9 ) c o n t a i n m e n t s ys te m s a n da re e spec i a l l y use fu l w hen l a rge num ber s o f an ima l s a r e be ing r ea red .

P R I N C I P L E S O F D E S I G N A N D O P E R A T I O NB o t h f e e d e r s o p e r a t e o n t h e s a m e g e n e r a l p r i n c i p l e . A n e l o n g a t e dh o p p e r c o n t a i n i n g t h e f o o d s p a n s t h e w i d t h o f th e r e a ri n g ta b le . A s h a fta l o n g t h e b o t t o m o f th e h o p p e r b e a r s a s e ri es o f d ia m e t r i c a ll y - o p p o s e dno tc hes (d ry f eede r ) o r s lo ts (we t f eede r) . T he sha f t ro ta t e s a s t he hop pe ris p u s h e d f r o m o n e e n d o f th e r e a r in g t ab l e to t h e o t h e r a n d a t e a c h r e v o -l u t i o n f o o d is t ra n s f e r r e d f r o m w i t h i n th e h o p p e r t o s u c c es si v e ro w s o fr e a r in g c h a m b e r s b e l o w . T o a c h i e v e u n i f o r m r o t a t i o n t h e s h a f t b e a r s at o o t h e d w h e e l a t e a c h e n d w h i c h l o c a t e in t o t ra c k s f a s te n e d t o t h e e d g eso f each r ea r ing t ab l e (F igs 1 and 2 ).

( a ) . \ ( b )

) ~ , . . . , , , , ~ ~ ' ~ ( c ) "/

( d )

F i g . 1 . T h e g e n e r a l a r r a n g e m e n t o f t h e d r y ( p e ll et ) f e e d e r ; ( a) h o p p e r w a ll s; (b ) c e n t r esupp or t ; ( c) sha f t; (d ) t oo the d d r ive w hee l ; (e ) re t a in ing p l a t e ; (f ) end wa l l o f hoppe r .


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Food distribution equipm ent for juvenile lobsters 279

Fig. 2. Th e gene ral arrangem ent of the w et (my sid) feeder: (a) hopper tube; (b) baffles;(c) slots in hopper; (d) shaft housing tub e; (e) water distribution man ifold; (f) water inletpipe: (g) water feed to shaft housing (one of three); (h) water jet man ifold; (i) feed to waterjet m anifold: (j) ove rflow from hopp er; (k) retaining ring for screen ; (1) screen ; (m) spin-dle; (n) toothed drive wheel.

I n t h e c a s e o f t h e w e t ( m y s i d ) f e e d e r , t h e f r e s h l y - t h a w e d m y s i d s a r ek e p t i n s u s p e n s i o n b y a s e ri e s o f s m a l l w a t e r j e ts a i m e d i n t o t h e h o p p e rf r o m a n e x t e r n a l s u p pl y . A s e r ie s o f b a f fl e s w i t h i n t h e h o p p e r r e d u c e ss p l a s h i n g a n d a s s i s t s i n m a i n t a i n i n g a u n i f o r m s u s p e n s i o n a n d d i s t r i b u -t io n o f f o o d o r g a n i s m s . B o t h f e e d e r s w e r e m a d e t o t h e sa m e o v e r a lld i m e n s i o n s i n o r d e r t o f it o u r r e a r in g t ab l es w h i c h m e a s u r e d2 .9 4 x 0 . 51 0. 1 5 m d e e p . T h e i n d i v i d u a l c o n t a i n e r s o n t h e r e a r i n g t a b l em e a s u r e d 5 x 5 c m w h i c h m e a n t t h at fo o d d e p o s i t i o n h a d t o o c c u r e v e r y5 c m a l o n g t h e t ab l e. D i f f e r e n t s i z e d c o n t a i n e r s w o u l d , o f c o u r s e , r e q u i r ed i f f e re n t d i a m e t e r s h a ft s.

C O N S T R U C T I O N O F D R Y ( P E L I . E T ) F E E D E RT h e w a ll s o f t he h o p p e r w e r e c u t f r o m 1 2.7 m m u P V C s h e et a n d h e ldt o g e t h e r w i t h e i g h t O B A b r a s s b o lt s. A c e n t r e s u p p o r t w a s a d d e d t o g i v er ig id it y. T h e s h a ft w a s m a c h i n e d t o a d i a m e t e r o f 3 3 m m f r o m a so l idu P V C r o d 6 0 0 m m in le n gt h. A t e a c h e n d t he d i a m e t e r w a s r e d u c e d t o


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280 J. F. Wickins, E. Jones, T. W. Beard and D. B. Edwards2 0 m m f o r a d i st a nc e o f 2 0 m m to a c c o m m o d a t e a t o o t h e d d r iv e w h ee l.E i g h t d i a m e t r ic a l ly - o p p o s i n g p ai rs o f i n d e n t a t io n s ( 5 m m d i a m e t e r, 2 - 3m m d e e p ) w e r e d r i l le d 5 5 m m a p a r t t o c o i n c id e w i t h t h e s e p a r a ti o n o ft h e r e a ri n g c h a m b e r s . T h i s d i m e n s i o n a l l o w e d f o r t h e t h ic k n e s s o f th ec o n t a i n e r w a ll s.

T h e s h a f t w a s s u p p o r t e d a t b o t h e n d s b y T u f n o l b u s h e s ( 4 5 m mo .d . x 1 2 7 m m w i d e ) s et in t o t h e e n d s o f th e h o p p e r i n s u c h a w a y t h a tt h e s i d e w a l ls o f t h e h o p p e r a b u t t e d t h e s h a f t a lm o s t t a n g e n t ia l ly (F ig . 3).A g r o o v e (3 m m w i d e x 3 m m d e e p ) w a s m a c h i n e d 3 0 m m f r o m o n e e n do f th e s h a ft ; t h is a c c o m m o d a t e d a r e t a in i n g p la t e w h i c h w a s a t t a c h e d t oo n e e n d w a ll o f th e h o p p e r .

F i g . 3 .

(b ) )/

End view of the dry (pellet) feeder showing position of hopper walls relative tothe shaft. Key as in ca ption to Fig. 1 but with (d) om itted; (g) Tufn ol bush.

T h e t o o t h e d w h e e ls w e r e m a d e f r o m a 4 5 m m d i a m e t e r u P V C b la n k,1 4 m m w i d e, a n d m a c h i n e d t o t h e d i m e n s i o n s i n F ig . 4.

C O N S T R U C T I O N O F W E T (M Y SID ) F E E D E RT h e m a i n b o d y o f th e f e e d e r w a s m a d e f r o m t w o P e rs p ex t u b es ( 4 m mw a l l t h i c k n e s s ) g l u e d t o g e t h e r (F i g . 2 ). A l a r g e ( 7 0 m m o .d .) t u b e s e a l e dw i th tw o e n d c a p s f o r m e d t h e h o p p e r , a n d a s m a ll e r o p e n - e n d e d (3 0 m mo . d . ) t u b e h o u s e d t h e r o t a t i n g s h a f t . B e f o r e a s s e m b l y , f i a t s w e r em a c h i n e d o n e a c h t u b e t o f ac il it at e g lu in g . T h e t o p o f th e h o p p e r t u b e


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Fo od d is tr ibu t ion equ ipm ent for ]uvenile lobsters 281

Fig . 4 .

4 5 r a m

- r l m j 1 .5 m m R a d i u so n 3 7 r a m P C D

- >.

4 B A A l l e n s c r e w

Deta i ls of the too the d dr iv ing wheel f rom th e dr y (pel le t) feeder .

w a s o p e n e d b y c u t t i n g a n e l o n g a t e d s l o t (3 0 x 4 2 0 m m ) d i a m e t r i c a ll yo p p o s i t e t h e m a c h i n e d f la t a n d t h e t u b e s w e r e g l u e d t o g e th e r .E ig h t s em i -c i r cu l a r ba f f le s (5 m m th i ck ) were g lued a t app rox im a te ly4 5 m m i n te r v a ls w i t h in th e h o p p e r t o c o r r e s p o n d w i t h t h e d i m e n s i o n s o ft h e l o b s t e r r e a r i n g c h a m b e r s . E i g h t s l o ts ( 2 0 x 1 2 "7 m m ) w e r e m a c h i n e dt h r o u g h t h e b o t t o m o f t h e h o p p e r a n d i n t o t h e a b u t t i n g s h a f t h o u s i n g ,o n e i n t h e c e m r e o f e a c h c o m p a r t m e n t f o r m e d b y t h e b a ff le s. A f u r t h e re igh t s lo t s (10 x 15 m m) were cu t d i am e t r i ca l ly opp os i t e i n t he sha f thous ing .O n o n e s id e o f th e h o p p e r w a s a t t a c h e d a 2 3 m m i.d . w a t e r d i st ri b u -t i o n m a n i f o l d h e l d i n p o s i ti o n b y u P V C b a r s a t t a c h e d t o t h e h o p p e r e n dcaps (F ig . 5). Th i s m an i fo ld was b l ank ed o f f a t each en d a nd r ece ived

(u )

Fig . 5 . Deta i ls of the wate r f low sys tem of the wet (mysid) feeder . Ke y as in capt ion toFig . 2 bu t w i th (1), (m) and (n) om it ted; (o) bored out centre o f shaf t; (p) counter bor edslot: (q) hole to shaft cen tre (one o f three); (u) levell ing plate .


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2 8 2 J . F . Wickins , E . Jones , T . W. Bea rd and D. B . Edw ardsw at e r t h rou gh a ho l e (8 m m d i am e t e r ) cu t i n t he t op . W a t e r le f t t he m an i -fo l d t h rough t h ree f l ex ib l e p i pes w h i ch j o i ned on t o r i g id p i pes g l ued on t oone s i de o f t he sha f t hous ing . Pe r spex b l ocks w ere g l ued i n p l ace t o sup -po r t t he a t t ach m en t o f t he se p i pes . Tw o a dd i t i ona l p i pes l e ft t he m an i fo l dto p r o v i d e e i g h t j e ts o f w a t e r in t o e a c h c o m p a r t m e n t w i t h in th e h o p p e rt o k e e p t h e f o o d i n s u s p e n s io n .T h e s h a f t w a s m a d e f r o m t w o l e n g t h s o f 2 5 . 4 m m d i a m e t e r s o l i duPV C ba r . Each ba r w as bo red ou t a l ong i t s en t i r e l eng t h u s i ng a 9 .5d i am e t e r l ong - se r i e s d r i l l . A sp i go t - socke t j o i n t w as m ach i ned fo r cen -t r a li s ing t he t w o ha l ves w h i ch w ere t hen g l ued t oge t he r . T he com pl e t esha f t w as t hen m ach i ned t o f i t w i t h i n t he sha f t hous i ng . The ove ra l ll e n g t h o f t h e s h a f t w a s 5 3 0 m m b u t 9 . 5 - m m d i a m e t e r s p i n d l e s w e r ei n s e r te d i n t o e a c h e n d t o a c c o m m o d a t e t h e t o o t h e d d r i v e w h e e ls . T h esp i nd l e s i nc reased t he ove ra l l l eng t h to 66 5 m m . E i gh t s lo t s (12 x 2 m m )w ere cu t t h rough t he d i am e t e r o f t he sha f t a t i n t e rva l s t o co i nc i de w i t ht he s l o t s i n t he hoppe r and sha f t hous i ng . O ne s i de o f each s l o t w ascou n t e rb o re d (13 x 2 x 2 m m deep ) (F i g . 6 ). To r educ e f r i c t ion be t w eent he ro t a t i ng sha f t and t he sha f t hous i ng , s i x r eces se s w ere m ach i ned i nt he sha f t be t w een a l l bu t t he m i dd l e p a i r o f s lo ts .T h r e e h o l e s ( 4 m m d i a m e t e r ) w e r e d r i l l e d t h r o u g h o n e s i d e o f t h esha f t o r t ho gon a l l y t o t he p l ane o f the s l o ts t o l i nk w i t h the cen t r a l bo re .T h e s e t h r e e h o l e s c o i n c i d e d o n c e e v e r y r e v o lu t i o n w i th t h e t h r e e w a t e ri n l e t p i pes g l ued t o t he sha f t hous i ng . A l oca t i on g roove (5 2 m m deep )w a s m a c h i n e d a r o u n d o n e e n d o f t h e s h af t.

A l u m i n i u m - t o o t h e d w h e e ls (2 2 m m d i am e t e r) w e r e m o u n t e d o n e a c hend sp i nd l e . O ne w hee l w as a l l ow ed t o f l oa t on i t s sp i nd l e by v i r t ue o ff l a t s m ach i ned on t he sp i nd l e and w hee l t o com pensa t e fo r i r r egu l a r i t i e s

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( n ) " ' " ~F i g . 6 . D e t a i l s o f t h e s h a f t o f t h e w e t (m y s i d ) f e e d e r . K e y a s i n c a p t i o n s t o F i g s 2 a n d 5 ;

( r) f l a t m a c h i n e d o n s h a f t s p i n d l e ; (s ) r e t a i n i n g b o l t ; (t ) m a c h i n e d r e c e s s ( o n e o f si x) .


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Food distribution equipm ent for juvenile lobsters 283i n t h e g u i d e r ai ls a n d t r a c k s . A n y l o n b o l t w a s t h r e a d e d i n t o th e e n d o ft h e s p i n d l e t o p r e v e n t w h e e l lo s s.

A l e v el li n g p l a t e (8 0 8 0 m m u P V C ) w a s a t ta c h e d t o o n e e n d o f t h eh o p p e r a n d r o d e o n t o p o f t h e tr a c k t o p r e v e n t t il ti ng . T h e p l a t e w a sa t ta c h e d b y m e a n s o f n y l o n b o l ts a n d s p a c in g w a s h e r s t o a n a t ta c h m e n tp l a te ( 1 8 0 x 5 0 m m P e r s p e x ) g l u e d o n t o t h e h o p p e r e n d c a p . T h e h e i g h to f t h e l e v e ll in g p l a t e w a s a d j u s t a b le b y m e a n s o f s l o t t e d h o l e s t h r o u g hw h i c h t h e f i x i n g b o l t s p a s s e d . A c u t a w a y i n t h e l e v e l li n g p l a t e a l l o w e dc l e a r a n c e f o r th e p r o t r u d i n g s h a f t s p i n d le .

T R A C K I N GT h e t ra c k i n g s e rv e d b o t h t y p e s o f f e e d er a n d w a s m o u n t e d a l o n g e a c hs i d e o f t h e r e a r i n g t r o u g h s ( F ig . 7 ). E a c h l e n g t h o f t r a c k w a s m a d e b yr o u t i n g a c h a n n e l (5 m m w i d e b y 5 m m d e e p ) a l o n g o n e e d g e o f a p i e c eo f t i m b e r ( 3 0 0 x 5 0 x 2 5 m m ) . A 3 0 0 - m m l o n g s t ri p o f s q u a r e m e s h p l a s -t ic n e t t i n g (5 x 5 r am ) w a s c u t a n d s t a p l e d t o th e t i m b e r s o th a t a c o n t i n u -o u s r o w o f s q u a r e m e s h e s w a s a li g n e d o v e r t h e ch a n n e l . T w o l e n g t h s o f9 0 a n g l e p l a s t i c s t r i p w e r e t h e n s t a p l e d t o t h e s i d e s o f t h e t i m b e r t oc o v e r u p t h e c u t e d g e s o f t h e m e s h .

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Fig. 7. Th e tracking attached to a rearing trough: (a) rearing trough; (b) routed ch annelin timb er fram e: ~c) cut strip of plas tic me sh; (d) plastic edging strip.


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2 8 4 J . F , Wickins , E . Jones , T . W. Bea rd and D. B . Edw ardsO P E R A T I O N O F D R Y (P E L L ET ) F E E D E R

The hoppe r was f i l l ed a lmos t t o capac i ty wi th g raded pe l l e t s , 1 . 5 -2 . 0m m n o m i n a l siz e. T h e s h a ft w a s r o t a t e d m a n u a l l y u n t il t h e a l ig n m e n t o fth e inde n ta t ion s was su ch tha t t he f i rs t de l ive ry o f pe l le t s wo u ld o ccur i nt h e f ir st ro w o f r e a ri n g c o m p a r t m e n t s . T h e f e e d e r w a s t h e n p l a c e d a t o n ee n d o f th e t r a c k a n d p u s h e d s t ea d i ly f o r w a r d t o t h e o t h e r e n d .

O P E R A T I O N O F W E T (M Y SID ) F E E D E RBe fore f il li ng the h op pe r t he sha f t was ro t a t ed m anua l ly un t i l t he s lo t s inthe base o f t he ho pp e r w ere o cc lud ed ( sha f t s l o ts ho r i zon ta l ) so t ha t t hen e x t q u a r t e r r e v o l u t i o n w o u l d a l ig n t h e c o u n t e r b o r e d e n d s o f th e s h a f ts lo ts w i th t hose i n t he ho pp e r ba se i n o rd e r t o r ece ive the f i rs t cha rge o fm y s i ds . A p p r o x i m a t e l y e q u a l q u a n t i ti e s o f n e w l y - th a w e d , w a s h e d m y s i ds h r i m p w e r e t h e n p l a c e d i n e a c h o f t h e e i g h t c h a m b e r s f o r m e d b y t h ebaf f les , thus f i ll ing the ho pp er to th e ha l f -way leve l .T h e m a c h i n e w a s p l a c e d s q u a r e l y a t o n e e n d o f t h e t r a c k i n g a n d alow-pres su re s eawa te r hose (5 mm i . d . ) connec t ed to t he wa te r i n l e tm an i fo ld f rom a t ap sup p ly ing the w a te r t ab l e. A s the wa te r l eve l i n t heho pp e r be gan to r is e , j e t s i n to each c ha m ber k ep t t he m ys ids swi r li ng insuspens ion . A sc reen p reve n ted the l o s s o f mys ids t h roug h the ove r f lowpipe ( s) . As soo n a s the h op pe r was a lm os t fu l l o f wa te r t he m ach ine wasp u s h e d s t ea d i ly f o r w a r d o v e r t h e r e a r in g c o m p a r t m e n t s t o t h e f a r e n d o fthe t r ack ing and the wa te r fl ow was tu rne d o f f. A t ea ch r ev o lu t ion o f t hes h a ft m y s i d s a n d w a t e r f l o w e d in t o t h e c o u n t e r b o r e d e n d s o f t h e s h a fts lo ts by g rav i ty ; a s t he sha f t con t in ued to ro t a t e , the ex i t f rom the ho pp e rwas oc c lude d p rev en t ing fu r the r i ng re s s o f mys ids . Jus t be fo re t he s lo tsb e c a m e a l ig n e d w i t h th o s e a t t h e b o t t o m o f t h e s h a f t h o u s in g , t h e t h r e eho le s t o t he bo re o f t he sha f t li ned up wi th t he t h ree w a te r i n le t s a t t achedto the sha f t hous ing . Th i s momen ta r i l y app l i ed s l i gh t pos i t i ve p re s su rein to t he bo re o f t he sha f t wh ich a s s is t ed the dep os i t i on o f mys ids i n to t her e a r i n g c o m p a r t m e n t s a s s o o n a s t h e s l o t s c o i n c i d e d w i t h t h o s e a t t h ebo t tom o f t he sha f t hous ing . A t t he same t ime the s l i gh t pos i t i ve p re s su rei n th e b o r e a l so p r e v e n t e d e n t r y o f m y s i d s in t o t h e o p p o s i t e e n d s o f t h es lo ts i n the sha f t , i.e . t hose w h ich were no t cou n te rb ored . As the ro t a t i onc o n t i n u e d , t h e n e x t c h a r g e o f m y s i d s e n t e r e d t h e c o u n t e r b o r e d e n d s o ft h e s lo t s w h e n t h e y r e a c h e d t h e b o t t o m o f t h e h o p p e r a n d t h e c y cl e w a srepea t ed .


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Fo od distribution equ ipme nt for juvenile lobsters 285R E S U L T S

T o q u a n t i fy t h e r e li ab i l it y o f f o o d d e l i v e ry t h e f e e d e r s w e r e o p e r a t e do v e r n i n e tr a ys o f 80 c o m p a r t m e n t s e a c h a n d t h e n u m b e r o f p e l l e ts o rm y s i d s in e a c h c o m p a r t m e n t w e r e c o u n t e d . F r a g m e n t s o f f o o d r e t a i n e do n t h e 1 .5 m m m e s h f l o o r o f t h e c o m p a r t m e n t s w e r e c o u n t e d a s a va il -a b l e f o o d . T h e r e s ul ts f r o m e a c h t ra y r e c e i v in g p e ll e ts w e r e s u p e r -i m p o s e d ( T a b l e 1 ) a s w e r e t h e r e s u l ts f r o m t h o s e f e d m y s i d s ( T a b le 2 ).T h e m e a n n u m b e r s o f f o o d p a r ti c le s f o r e a c h c o m p a r t m e n t p o s i t io n int h e t r ay s w e r e d e t e r m i n e d a s w e r e t h e d i s t r ib u t io n s a n d n u m b e r s o f c o m -p a r t m e n t s c o n t a i n in g e i th e r n o f o o d o r p a r t ic l e s n u m b e r i n g m o r e o r l es st h a n 1 S .D . f r o m t h e o v e r a ll m e a n .

TABLE 1Th e M ean Nu m ber and Standard Erro r o f Food Part icles Distributed by the Dry (Pellet)Feeder in to N ine Trays of 80 Com partmen ts4.11 3-22 4.00 3-67 3.44 3.89 3-22 3,11 3-33 4.00( 0 . 2 0 ) ( 0 . 4 0 ) ( 0 . 4 4 ) ( 0 . 6 0 ) ( 0 " 3 8 ) ( 0 . 4 2 ) ( 0 . 6 0 ) ( 0 . 5 4 ) ( 0 . 6 5 ) ( 0 . 6 0 )3.78 4.67 3-89 3-22 4.89 3.56 4.00 3"56 3"87 3.44i 0 . 4 3 ) ( 0 . 5 0 ) ( 0 . 6 5 ) ( 0 . 6 2 ) ( 1 . 1 0 ) ( 0 - 3 4 ) ( 0 . 2 9 ) ( 0 . 6 9 ) ( 0 - 4 3 ) ( 0 . 4 7 )3.78 3.56 3.22 3.44 3.33 3.78 3.78 3.56 3.78 3"56( 0 . 5 5 ) ( 0 . 7 7 ) ( 0 . 5 5 ) ( 0 . 6 3 ) ( 0 . 7 6 ) ( 0 . 4 0 ) ( 0 . 5 5 ) ( 0 . 6 9 ) ( 0 . 4 0 ) ( 0 - 3 4 )3-78 3.67 3.56 3.56 3.11 3.33 4.00 3-22 3.78 4.00~ 0 . 3 2 ) ( 0 . 6 0 ) ( 0 . 3 8 ) ( 0 . 7 7 ) ( 0 . 2 6 ) ( 0 . 6 0 ) ( 0 . 4 1 ) ( 0 . 6 4 ) ( 0 . 4 6 ) ( 0 - 6 7 )3.44 2-56 3.56 3.44 3.67 3.44 3"00 2.67 3-67 3.44( 0 .4 4 ) ( 0 . 4 1 ) ( 0 . 3 8 ) ( 0 . 5 6 ) (0 '5 8) ( 0 " 6 0 ) ( 0 . 1 7 ) ( 0 . 4 4 ) ( 0 - 5 3 ) ( 0 .5 6 )3.44 3.33 2.67 3"56 3.67 3.22 3.44 3.11 3.44 2.89(0 .3 4~ (0 .4 7 ) (0 .5 0 ) (0 '5 8) (0 .6 2 ) (0 .4 9 ) (0 "5 6 ) (0 . 3 5 ) (0 "2 9 ) (0"39 )3.56 3.78 3.22 3.00 3.78 3'56 3.67 3.67 4.33 3.33( 0 . 2 9 ) ( 0 . 3 2 ) ( 0 . 4 9 ) ( 0 . 4 1 ) ( 0 . 4 0 ) ( 0 - 4 4 ) ( 0 . 4 1 ) ( 0 . 2 9 ) ( 0 . 8 2 ) ( 0 . 4 4 )3.11 3.56 3.44 3.89 4.00 3.22 4.00 3"89 3.67 3.33(0 -3 1 ) (0 4 1 ) (0'5 0) (0 -5 4 ) (0 "6 2 ) (0 "6 4 ) (0 -4 1 ) (0 "1 1 ) (0 "4 1 ) (0"29 )

P e l l e t f e e d e r

T h e m e a n n u m b e r o f f o o d p a r t ic l es r e t a in e d o n t h e m e s h f lo o r o f t h ec o m p a r t m e n t s w a s 3 . 55 (S .E . = 0 .0 6 ) a n d 9 1 % o f t h e c o m p a r t m e n t s c o n -t a in e d b e t w e e n 2 a n d 6 p ar ti cl es . O n l y 1 7 c o m p a r t m e n t s c o n t a i n e d m o r et h a n 6 p a r t ic l e s ( 2 . 4 % ) a n d o n l y 1 4 r e c e i v e d n o f o o d a t a ll ( 1. 9% ) . T h ef e e d i n g ra t e a c h i e v e d i n o u r n u r s e r y u n i t w a s j u s t u n d e r 6 m i n p e r 1 0 0 0l o b s t e r s . T h i s t i m e i n c l u d e d a l l n e c e s s a r y p e r i p h e r a l o p e r a t i o n s s u c h a sl o a d i n g t h e h o p p e r a n d m o v i n g i t f r o m o n e r e a r i n g t a b le t o t h e n e x t.


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286 J . [ :. W i c k i n s , E . J o n e s , T . W . B e a r d a n d D . B . E d w a r d sTABLE 2The Mean Number and Standard Error of Mysids Distributed by the Wet (Mysid)Feeder into N ine Trays of 80 Com partments

7"78 5"78 7"11 7"56 6"89 5-00 5"67 7"67 5"89 6"89(1 "2 2) ( 1 "1 4 ) ( 0 "9 6 ) ( 0 "9 1 ) ( 0 "7 3 ) ( 1 "0 4 ) ( 0 "5 5 ) ( 0 "7 1 ) ( 0 "8 1 ) ( 0 ' 3 9 )6"67 8"33 7-89 6-56 6"11 7"11 7"22 6"67 7-78 8'00( 1 '3 4 ) ( 1 "1 8 ) ( 1 "4 4 ) ( 1 "0 7 ) (1 "1 6 ) ( 0 "7 3 ) ( ! "1 6 ) ( 0 ' 6 9 ) ( 1 - 0 5 ) (1 "0 3)5'22 7-33 5-89 6-89 6'4 4 6-67 7"22 6"78' 7"78 6"89(0 "6 8) ( 1 "1 8 ) ( 0 "8 7 ) ( 1 "3 5 ) ( 1 ' 1 3 ) ( 1 "0 3 ) ( 1 "0 8 ) ( 0 "8 9 ) ( 0 "7 8 ) ( 0"72 )4"56 5"89 5"78 4"33 6"44 6"44 5-56 4"78 5"67 5"78( 0 "6 7 ) ( 1 "3 4 ) ( 0 - 6 6 ) ( 1 "1 1 ) ( 1 "4 2 ) ( 1 "3 9 ) ( 0 "6 9 ) ( 0 ' 5 2 ) ( 1 ' 0 3 ) ( 1 ' 0 4 )7"11 5"33 4"33 7"33 5"67 6'11 6-22 7"00 5'33 6"56( 0 "8 7 ) ( 0 "6 9 ) ( 0 "6 7 ) ( 0 "8 8 ) ( 0 "9 4 ) ( 0 "8 7 ) ( 1 "3 4 ) ( 0 "8 3 ) ( 0 ' 8 8 ) ( 0 ' 7 8 )4-00 5"11 5"22 5-67 5"44 5"33 4"89 5"89 5"22 6"00( 1 . 1 5 ) ( 1 . 4 7 ) ( 1 . 0 8 ) ( 0 . 9 1 ) ( 1 . 2 6 ) ( 0 . 6 9 ) ( 0 . 9 0 ) ( 1 . 0 6 ) ( 1 - 5 3 ) ( 1 . 2 9 )6.22 6-44 6.11 6.44 5"89 6-44 6.78 5.67 7.78 6.44( 1 . 0 8 ) ( 0 . 8 4 ) ( 0 . 6 1 ) ( 1 . 0 2 ) ( 1 . 1 2 ) ( 0 - 9 4 ) ( 0 . 9 4 ) ( 0 . 6 9 ) ( 1 . 1 8 ) ( 1 . 4 3 )6.33 5-33 4.44 4.67 4.89 4.78 4.56 4.67 5.11 3.56( 0 . 7 3 ) ( 1 . 1 4 ) ( 0 . 9 3 ) ( 0 . 9 7 ) ( 0 . 9 8 ) ( 1 . 3 4 ) ( 0 . 9 6 ) ( 0 . 8 5 ) ( 1 - 1 7 ) ( 1 . 0 0 )

M y s i d f e e d erT h e m e a n n u m b e r o f m y s i d s d e l i v e r e d w a s s li gh tly g re a t e r t h a n t h a t fo rp e l le t s a n d w a s 6 "0 9 ( S .E . -- 0 .1 1 ) p e r c o m p a r t m e n t . S e v e n t y - t h r e e p e rc e n t c o n t a i n e d b e t w e e n 3 a n d 9 m y s i d s a n d o n l y 15 c o m p a r t m e n t s w e r ee m p t y (2 .1 % ) w h i l e 1 02 c o m p a r t m e n t s c o n t a i n e d m o r e t h a n n i n e p i e ce so f f o o d ( 1 4 ,2 % ) . T h e f e e d i n g ra t e w a s j u s t u n d e r 1 7 m i n p e r 1 0 0 0 l o b -s t e r s . T h i s t i m e i n c l u d e d a l l o p e r a t i o n s e x c e p t t h a w i n g a n d w a s h i n g t h em y s i d s .

B o t h f e e d e r s s h o w e d s i m i l a r v a r ia b i li ty in t h e n u m b e r s o f f o o d p a r ti -c le s w h i c h t h e y d i s tr i b u te d t o e a c h c o m p a r t m e n t . T h e c o e ff ic ie n ts o fv a r i a t i o n w e r e 0 . 4 0 f o r t h e p e l l e t f e e d e r a n d 0 . 4 9 f o r t h e m y s i d f e e d e r .A p p l i c a t i o n o f th e o n e - s a m p l e r u n s t e st ( se e S i eg e l, 1 9 5 6 ) i n d i c a t e d t h a tt h e d i s tr i b u ti o n o f e m p t y c o m p a r t m e n t s i n e a c h t ri al w a s r a n d o m( P ~< 0. 62 ).

C O N C L U S I O N ST h e t w o f e e d i n g m a c h i n e s f u l f i l l e d t h e i r p r i m a r y f u n c t i o n w e l l i n p e r -m i t t i n g s u b s t a n t i a l s a v i n g s i n t h e t i m e s p e n t b y s t a f f f e e d i n g l a r g e n u m -b e r s o f i n d i v i d u a l l y - h o u s e d ju v e n i l e l o b s te r s . F e e d i n g t o o k a l it tl e l o n g e r


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Foo d distribution equ ipmen t or juvenile lobsters 287w i t h t h e w e t ( m y s i d ) f e e d e r b e c a u s e t h e h o p p e r c a p a c i t y w a s s m a ll a n dr e fi ll in g w a s n e c e s s a r y a f t e r e v e r y 3 2 0 l o b s t e rs ( t h e n u m b e r o f in d i v i -d u a l s i n o n e r e a r i n g t r o u g h ) . A l a r g e r c a p a c i t y h o p p e r w o u l d h a v er e q u i r e d s t r o n g e r t r ac k i n g an d g r e a te r h e a d r o o m b e t w e e n t h e st ac k s o ft r o u g h s i n o u r s y s te m . T h e e v e n n e s s o f t h e d i s t r ib u t i o n o f f o o d p a r t ic l e sa m o n g t h e r ea r in g c o m p a r t m e n t s b y b o t h m a c h i n e s w a s g o o d a l th o u g ht h e m y s i d f e e d e r w a s s l ig h t ly m o r e v a r i a b le t h a n t h e p e l l e t f e e d e r . O n l y as m a ll n u m b e r o f c o m p a r t m e n t s d i d n o t r e c e iv e f o o d a n d t h e ap p a r e n t l yr a n d o m d i s tr i b u t io n o f t h e e m p t y c o m p a r t m e n t s m e a n t t h a t i t w a su n l i k e ly th a t t h e s a m e l o b s t e r s w o u l d g o w i t h o u t f o o d t w i c e i n s u c ce s -s i on .

T h e d i s ta n c e b e t w e e n t h e f o u r t ra y s in e a c h o f o u r w a t e r tr o u g h s w a sv a r i a b le a n d t h e r e w a s t h e r e f o r e a c h a n c e t h a t a l i g n m e n t o f th e s l o tsc e n t r a l l y w i t h i n t h e r o w s o f r e a r i n g c o m p a r t m e n t s w o u l d n o t a l w a y so c c u r i n t h e s e c o n d , t h i r d o r f o u r t h t r a y s . I n p r a c t i c e , a s t h e r e s u l ts i n d i -c a te d , i t w a s r a r e f o r a n y r o w t o b e m i s s e d c o m p l e te l y .

R E F E R E N C E SBeard, T . W. , Richards , E R. & W ickins , J . E (1985) . Th e techn iques and prac t i -cabi l i ty of year- round product ion of lobs te rs , H om ar us gam m ar us (L), inlabora tory rec i rcula t ion systems. Fi sh R es. Tech. Rep. , M A F F Direc t . Fi sh.Res., Lo w estoft , (79), 1 -22 .Ch apm an, E (1983) . Co r re spo nd enc e conce rn ing Saunde rs Assoc i a te s Inc .Aqu acul ture Diges t, 8 (8) , 12-1 3 .Co nkl in , D. E . , Bo rdne r , C . E . , Garre t t , R . E . & Coffe l t, R . J . (1981 ). Im pro ve dfaci l i t ies for experimental cul ture of lobsters . J . Wld Maricult . Soc., 12 (1),5 9 - 6 3 .Conkl in , D . E . , D 'Abramo, L . R . & Norman-Bondreau , K . (1983) . Lobs t e r

nutri t ion. In: H an db oo k o f Mariculture, 1. Crustacean Aq uacu l ture, ed. J. EMcVey, CR C Press Inc ., Boca Ra ton , F lor ida , pp . 413 -23 .M alecha , S . R . , M ason o, S . & O nizaka , D. (1984) . Th e feasibi lity o f measur ingthe her i tabi l i ty of growth pa t te rn var ia t ion in juveni le f reshwater prawns ,Macrobrachium rosenbergi i (de M an). Aquacul ture , 3 8 , 3 4 7 - 6 3 .Micke lsen, R . W. , Infranger , R . C . & Heckmann, R . A. (1978) . Cul tur ing theA m e r i c a n l obs t e r (Homarus americanus) using a vert ical ly stacked cagesystem. Pro c. 9th A nn . Meet . Wld Maricult . Soc., At lan ta , Georg i a , US A, 3 -6Janua ry , pp . 723- 30 .Richards , E R. & W ickins , J . E (1979) . Minis t ry of Agricul ture , Fi sher ies andFood. Lobste r Cul ture Research. Lab. Leaf l . , MAFF Direc t . Fi sh. Res . ,Low estof t , (47) , 1-3 3.Siegel, S. (1956). Nonp arametric Statistics fo r the Beha viou ral Sciences,M cGraw-H i ll , Ko gakusha L td ., Tokyo , 31 2 pp .


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288 J.F. W ickins, E. Jones, T. W. Beard and D. B. Ed wardsT.V.A. (1978) . W astehea t u t i l iza t ion fo r ag r icu l tu re and aquac u l tu re , Tennes seeVa l l ey Au th o r i ty an d E lec t r i c Po wer Resea rch In s t i t u t e , Tech . Rep . , B-1 2 ,1 - 4 0 5 .Va n Ols t , J . C., Car lberg , J . M . & Ford , R . E (1977). A desc r ip t ion o f in tensivecu l tu r e sy s t em s fo r th e Am er ican lo b s t e r ( H o m a r u s a m e r i c a n u s ) a n d o t h e rcann iba l i s t ic c rus taceans . Proc . 8 th An n . W ksho p W ld Mar icu lt . Soc . , S anJo s6, Co s ta Rica , 9 - 1 3 Jan u a ry , p p . 2 7 1 -9 2 .Wick ins , J . K (1983) . On the t rack o f p rof i t s f rom lobste rs . Fish Farmer , 6 (1),2 0 - 1 .

wickins 1987 aquacultural-engineering

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