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Aquacultural Engineering 1 ( 1 9 8 2 ) 5 - 9

P H O T O E L E C T R I C M E A S U R E M E N T O F L O B S T E R ( H O M A R U SA M E R I C A N U S ) R E S P ONS E T O F E E D AT T R AC T ANT S

R O B E R T C . B A Y E R , ' ~ J O H N R I L E Y , $ J A M E S H . R I T T E N B U R G , ' ~D A L E F . L E A V IT T '~ a n d M A R G I E L E E G A L L A G H E R -~Departments o f tAnimal and Veterinary Sciences, and gAgricultural Engineering,University of Maine, Orono, Maine 04469, USA

ABSTRA CTThe apparatus described was designed to measure the speed and direction of lobsterresponse to feed attractants with minimal observer influence on the test animal.Lobster activity was monitored in an 84xlOx10in (213x25x25cm) plexiglastank based on interruption of photoelectric cells. Impulses from the photocells triggerthe pens o f a 6-channel event recorder. During its operation the apparatus is coveredwith an opaque plastic sheet. Lobster behavior was such that the animals alwayssettled in one of the chamber ends and the test material could be injected at the farend. The lobsters responded to a variety o f test materials.

I N T R O D U C T I O NSeveral methods have been used previously to study the reaction of lobsters to con-stituents in their environment. Mackie and Shelton (1972) designed a chamber witha shelter habitat and one-way mirrors for direct observation of lobsters' behavior whenexposed to potential attractants, without the observer influencing this behavior.McLeese (1972) blindfolded lobsters, tagged them with fluorescent paint, andrecorded movement using ultraviolet light. A photograph, taken with a three-minutetime exposure, traced the path of the lobster in its response to attractants. Allenet al. (1975) pumped water from a pre-soaked bait in a small tank into a larger tankcontaining a mature Dungeness crab (Cancer magister). Direct behavioral observationswere made of the crab's response.

The apparatus described in this paper was designed to measure and record thedirectional response of lobsters to feed attractants with minimal observer influenceon the test animal. 5Aquacultural Engineering 0 1 4 4 - 8 6 0 9 / 8 2 / 0 0 0 1 - 0 0 0 5 / 1 ; 0 2 . 7 5 O A p p l i e d S c i e n c e P u b l i s h e r s L t d ,E n g l a n d , 1 9 8 2P r i n t e d i n G r e a t B r i t a in

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6 BAYER et aLM A T E R I A L S A N D M E T H O D S

T h e a c t i v i ty m o n i t o r i n g s y s t e m i s b a s e d o n t h e i n t e r r u p t i o n o f l ig h t b e a m s b y t h em o v i n g l o b s t e r s. A t a n k 8 4 1 0 x 1 0 i n ( 2 1 3 2 5 2 5 c m ) w a s f a b r i c a t e d f r o m1 in ( 0 - 6 3 5 c m ) p l e x ig l a s , w i th a n g l e i r o n r e in f o r c in g a t t h e c o r n e r s , a n d a r i g id s u p -p o r t i n g b a se o f 3 i n ( 1- 9 0 5 c m ) p l y w o o d . S i x p h o t o e l e c t r i c c el ls w e r e m o u n t e d a l o n go n e s i de o f t h e t a n k a t e q u a l s p a c in g s w i th s i x l i g h t s o u r c e s a lo n g t h e o p p o s i t e s i d e ,e a c h b e i n g a i m e d a t i ts c o r r e s p o n d i n g p h o t o c e l l ; s ee F i g . 1.

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,N..~LE.J " ~ ~ ~ ~ ~f~/4"Plexiglas L I / 2 " x l / 2 " A n g l e ~ '5 /4 "P lywood

I~lO"-~lP H O TO C EL L . . . ~ K . . / L IG H T S O U R C E

Section A-AF i g , 1 . E x p e r i m e n t a l a c t i v it y m o n i t o r i n g a p p a r a t u s .

T h e o u t p u t s ig n al f r o m e a c h p h o t o c e l l o p e r a t e s t h e c o i l o f a r e la y , t h e o u t p u t o fw h i c h is c o n n e c t e d t o o n e c h a n n e l o f a 6 - c h a n n e l e v e n t r e c o r d e r . W i t h t h e p h o t o c e l lr e c e iv i n g li g h t f r o m t h e s o u r c e , t h e r e l a y c o n t a c t s a r e h e l d o p e n a n d n o s ig n al r e a c h e st h e r e c o r d e r . I n t e r r u p t i o n o f t h e l ig h t b e a m c a u se s t h e r e la y t o c l o se , a c t u a t i n g t h ee v e n t r e c o r d e r p e n f o r t h a t p a r t i c u la r c h a n n e l . W h e n th e li g h t b e a m i s r e s t o r e d , t h er e c o r d e r p e n r e t u r n s t o a c e n t ra l ' o f f ' p o s i t i o n . F i g u r e 2 s h o w s a sc h e m a t i c o f t h ei n s t r u m e n t a t i o n c i r c u i t r y .

T h e l ig h t s o u r c e s a n d p h o t o c e l l s w e r e d e s i g n e d to o p e r a t e u p t o 1 8 0 c m a p a r t .A t t h e 6 0 c m s e p a r a t i o n i n t h is a p p l i c a t i o n t h e a m o u n t o f l i gh t r e c e iv e d is f a r g r e a t e rt h a n t h a t n e e d e d t o g e n e r a t e a si gn a l s t r o n g e n o u g h t o o p e r a t e t h e r e l a ys . I t w a s f e l tt h a t t h e l e v el s o f l i g h t i n g i n t h e t a n k s h o u ld b e k e p t a s l o w a s p o s s ib l e , p r im a r i l y t or e d u c e d i s t r a c t io n t o t h e l o b s t e r , b u t a l so b e c a u s e t h e lo b s t e r i s b y n a t u r e n o c t u r n a la n d w o u l d b e m o r e l i k e l y t o r e s p o n d n a t u r a l l y i n a r e l a t i v e l y d a r k e n v i r o n m e n t . T h el i g h t s o u r c e s w e r e t h e r e f o r e p a r t i al l y c o v e r e d s o t h a t o n l y a t h i n ve r t ic a l b e a m w a sp r o j e c t e d . T h e t a n k w a s f il le d w i t h w a t e r d y e d t o s i m u l a t e t h e p o o r e s t v i s i bi li ty , d u et o s u s p e n d e d s il t, l i k e ly t o b e e n c o u n t e r e d , a n d t h e s i ze o f t h e l ig h t b e a m w a sg r a d u a l l y r e d u c e d u n t i l f u r t h e r r e d u c t i o n a c t u a t e d t h e r e la y a n d e v e n t r e c o r d e r . T h e s et e s ts w e r e c o n d u c t e d w i t h t h e t a n k c o v e r e d b y b l a c k p o l y e t h y l e n e f il m s o t h a t t h ee f f e c t s o f a m b i e n t l i g h t o n t h e p h o t o c e l l s w o u l d b e r e d u c e d a s m u c h a s p o s s ib l e .

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LOBSTER RESPONSE TO FEED ATTRACTANTS 7

, , 5 V AC ~ ~ ' ~ '~ '~ '[~ L I G H T S O U R C E S( S I G M A S E R I E S 8 )

+ 1 2 V D C ~ ( D A Y T O NSPOT)- 1 2 V D C E V E N T R E C O R D E R1 1 5 V A C ( E S T E R L I N EA N G U S )( R E C O R D E R R I V E ( 8 - C H A N N E L

Fig. 2 . Schem at ic of inst rum entat ion ci rcui t ry of act iv i ty mo ni tor ing apparatus.

T h e t a n k w a s p r o v i d e d w i t h w a t e r i n l e t a n d o v e r f lo w c o n n e c t i o n s . T o p e r f o r m af e e d i n g re s p o n s e t e s t , t h e i n l e t w a s c o n n e c t e d t o a s u p p l y o f s e a w a t e r , t h e t a n k w a sf i ll e d , a n d t h e n t h e f l o w r a t e w a s a d j u s t e d t o g i ve th e d e s i r e d fl o w t h r o u g h t h e t a n k .T h e t e s ts w e r e c o n d u c t e d u s i n g l o b s t e r s w e i g h i n g 4 0 0 - 5 0 0 g ; t h e y w e r e f a s te d f o r2 - 4 w e e k s p r i o r to t h e t e s t s , s in c e M a c k i e a n d S h e l t o n ( 1 9 7 2 ) h a d s h o w n t h a t f a s t e dl o b s t e r s w e r e m o r e r e s p o n s iv e t o a t t r a c t a n t s . T h e l o b s t e r s w e r e p l a c e d i n th e t a n k a n dg i ve n 1 5 m i n t o a c c l i m a t e a s s e a w a t e r f l o w e d t h r o u g h t h e t a n k .

A f t e r t h is w a i t i n g p e r i o d , w a t e r f l o w w a s s t o p p e d a n d t h e t e s t s u b s t a n c e w a si n j e c t e d i n to t h e w a t e r i n l e t t u b e . T h e i n l e t v a lv e w a s th e n o p e n e d f o r a p p r o x i m a t e l y1 s to f o r c e t h e t e s t s u b s t a n c e i n t o t h e t a n k , t h i s t i m e b e i n g d e t e r m i n e d b y e a r li e r d y ei n j e c t i o n t e s t s a i m e d a t d e l i v e ri n g t h e d y e t o t h e p o i n t w h e r e t h e i n le t p i p e j o i n e dt h e t a n k .

A s t h e t e s t lo b s t e r m o v e d d o w n t h e t a n k in r e s p o n s e t o t h e f e e d i t s m o v e m e n t w a st r a c e d o n t h e r e c o r d e r a s a s e ri e s o f e v e n t s c o r r e s p o n d i n g t o e a c h i n t e r r u p t i o n o f al i g h t b e a m . T h e s e q u e n c e o f e ve n t s t h u s a l l o w e d d e t e r m i n a t i o n a s to t h e r e b e i n g ap o s i t iv e o r n e g a t i v e re s p o n s e t o t h e f e e d o r a t t r a c t a n t , a n d t h e s p a c i n g o f th e e v e n t sa l l o w e d a c o m p a r i s o n o f t h e r a te o f t h e r e s p o n s e . K n o w i n g t h e d i s t a n c e b e t w e e n t h ep h o t o c e l l s a n d t h e s t r ip c h a r t p a p e r s p e e d , q u a n t i t a t i v e v a lu e s f o r th e s p e e d o fr e s p o n s e c o u l d b e o b t a i n e d i f n e c e s sa r y . F i g u r e 3 s h o w s a s a m p l e o f r e c o r d e r c h a r t f o ra p o s i t iv e re s p o n s e i n w h i c h t h e l o b s t e r m o v e d d i r e c t l y f r o m o n e e n d o f th e t a n k t ot h e o t h e r e n d a t w h i c h t h e a t t r a c t a n t w a s l o c a t e d .

A l o b s t e r w a s u s e d f o r th r e e o r f o u r t e s t s u b s t a n c e s a n d t h e n r e p l a c e d . A l o b s t e rh e m o l y m p h i n j e ct i o n i n t o t h e t a n k a f te r th i s n u m b e r o f t es t s p r o d u c e d a n e g a ti v er e s p o n s e , i n d i c a t i n g t h a t t h e a n i m a l w a s f a t i g u e d o r c o n d i t i o n e d i n s o m e w a y ; l o b s t e rh e m o l y m p h h a s b e e n s h o w n t o b e a p o t e n t n a t u r a l a t t r a c t a n t .

A t t r a c t a n t s o f v a r i o u s t y p e s w e r e t e s t e d . A m i n o a c i d s w e r e t e s t e d a s h a d p r e v i o u s l yb e e n d o n e b y M c L e e s e ( 1 9 7 2 ) , M a c k i e a n d S h e l t o n ( 1 9 7 2 ) , a n d o t h e r s , a l o n g w i t h

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8 BAYER e t a l .

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Fig. 3 . Sa mple st r ip c ha r t r e cor d ing showing move m e nt o f l obs te r s f r om one e nd o f t a nk t oa no the r .

T A B L E 1Summa r y o f r e sponse o f l obs te r s t o t e s t a t t r a c t a n t s

T e s t s u b s t a n c e D a y r e s p o n s e N i g h t r e s p o n s eXanth ine + +Fish flav or a + -B alanineTaur ine + -Glut ami c ac id - -Gua nin e +_Lysin e + +L obs t e r he mol ymph + +Anis e a - +Uric acid - -A r ge n ine +H o m o c y s t i n e +Choco la te f lavor a +Chic ken fat f lavor a - -/- leucine +L ys ine a nd t r ime t hy l a m ine +Her r ing meal solubles +Glyc ine +Liver f lavor aWhole egg her r ing oi l emuls ionCheese f lavor a +Musse l ext rac t ++ Indica tes pos i t ive response ; - indica tes nega t ive response ; a blank indica tesnot t r ied, a Kem in Indust r ies , Des Moines , Iowa, USA.

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LOBSTER RESPONSE TO FEED ATTRACTANTS 9some amino acid metabolites. Synthetic food flavors, animal feed flavor additives,sea water soluble extracts of feed ingredien ts and fish oil emulsions were also tested.

RESULTS AND DISCUSSIONSince observations of lobsters indicated that they were more active at night, both dayand night trials were condu cted . Table 1 summarizes the results of the trials. It can beseen that lobsters demonstrated different responses to the same substance dependingon whether the test was performed during the day or at night.

The ap paratus itsel f proved to be simple to use and relatively trouble-free. Alth oughmost of the testing was done inside a laboratory, the apparatus was designed to beportable. It could be transported by station wagon to a lobster pound or other remotelocati ons, a nd a small gasoline generator could be used to powe r a circulating pump ,the light sources and the event recorder.

REFERENCESAllen, W. V., Frederick, E. C. & Wong, R. (1975). Experiments on the development of an artificialbait for Dungeness crab, C anc e r m ag i s t er . Se a G ran t Bu l l e t i n , HSU-SG-7.McLeese, D. W. (1972). Orientation of lobsters ( H o m a r u s a m e r i c a n us ) to odor. J. Fish . Res . Bd.Can., 30,839-40.Mackie, A. M. & Shelton, R. G. J. (1972). A whole-animal bioassay for the determination of foodattractants of the lobster, H om arus gam m arus . "Mar. B io l . , 14 , 2 17 - 21 .