URGENT PROBLEMS O F MOLLUSKAN FARMING

V i c t o r L. Loosanoff l U n i v e r s i t y o f t h e P a c i f i c

P a c i f i c Marine S t a t i o n D i l l o n Beach, C a l i f o r n i a 94929

ABSTRACT

The a r t i c l e emphasizes some o f t h e most u r g e n t problems f a c - i n g molluskan farmers. Among them i s t h e need f o r deve loping methods t h a t w i l l r a p i d l y p u r i f y mol lusks f e e d i n g on t o x i c forms o f p lankton and t h u s becoming t o x i c themselves . i n g of t h e phys io logy o f n u t r i t i o n w i t h commercial mollusks, and development and a broad u s e o f s p e c i a l l y prepared foods are o t h e r urgent problems t o be s o l v e d . S t u d i e s of e p i z o o t i c s and d e v i s i n g means f o r t h e i r c o n t r o l i s a l s o an impor tan t f i e l d t h a t should be en larged on a n i n t e r n a t i o n a l b a s i s . Ques t ions of r a d i c a l changes i n laws r e f e r r i n g t o m a r i c u l t u r e , and t h e need f o r t r a i n i n g of f u t u r e m a r i c u l t u r i s t s are b r i e f l y d i s c u s s e d i n t h e a r t i c l e .

B e t t e r understand-

INTRODUCTION

It i s a n o l d s t o r y t o every mar ine b i o l o g i s t t h a t m a r i c u l t u r e i s an a n c i e n t a r t and t h a t i t has been p r a c t i c e d f o r over 2,000 years i n some p a r t s o f A s i a and Europe. What i s u s u a l l y not added t o t h i s s t a t e m e n t i s t h a t f o r t h e same 2,000 y e a r s i t made v i r t u a l l y no p r o g r e s s . True, i n t h e middle of t h e 19th century t h e c u l t u r e of o y s t e r s and mussels was somewhat updated, while i n t h e United S ta t e s and s e v e r a l European c o u n t r i e s e f f o r t s were made t o grow i n h a t c h e r i e s c e r t a i n s a l t w a t e r f i s h e s and a l s o t h e American l o b s t e r . Some o f t h e l o b s t e r h a t c h e r i e s l o c a t e d i n New England cont inued t o o p e r a t e u n t i l t h e e a r l y 1940 ' s when it was concluded t h a t t h e i r e f f o r t s d i d not h e l p t o i n c r e a s e t h e n a t u r a l

'Present a d d r e s s : 17 Los Cerros Dr ive , Greenbrae, C a l i f o r n i a 94904

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342 WORLD MARICULTLIRE SOCIETY WORKSHOP

p o p u l a t i o n , However, i n t h e c a s e of P a c i f i c salmon, which i s ana- dromous, r e s u l t s were more s u c c e s s f u l and h a t c h e r i e s became an impor tan t f a c t o r i n m a i n t a i n i n g t h e i r numbers.

I n t h e c u l t i v a t i o n of commercial mol lusks l i t t l e p r o g r e s s h a s been made s i n c e t h e days of t h e Romans. R e c e n t l y , however, be - cause of t h e a v a i l a b i l i t y of mechanical f a c i l i t i e s , e s p e c i a l l y power-driven b o a t s , i t became e a s i e r t o dredge o y s t e r s , c lams, and s c a l l o p s on n a t u r a l beds , and sometimes move them from one bottom a r e a t o a n o t h e r . This v i r t u a l l y ended "farming" p r o g r e s s except t h a t some s u c c e s s f u l e f f o r t s were r e c e n t l y made t o deve lop methods t o c o n t r o l s e v e r a l of t h e most d e s t r u c t i v e enemies of b i v a l v e s , such a s s t a r f i s h o r b o r i n g gas t ropods . (Loosanoff , 1961) .

Regard less o f a l a r g e number of s o - c a l l e d o y s t e r b i o l o g i s t s employed d u r i n g t h e f i r s t h a l f of t h i s c e n t u r y by d i f f e r e n t govern- ments and s t a t e s , r e l a t i v e l y l i t t l e p r o g r e s s was made i n b a s i c s t u d i e s l e a d i n g t o b e t t e r u n d e r s t a n d i n g of t h e p h y s i o l o g i c a l and e c o l o g i c a l requi rements o f commercial mol lusks . Even now we have r a t h e r incomple te knowledge of t h e n u t r i t i v e requi rements of t h e m a j o r i t y o f commercial s p e c i e s , a s i t u a t i o n which c l e a r l y demon- s t r a t e s our backwardness. Obviously, n e i t h e r c a t t l e b r e e d e r s nor ch icken fa rmers could have progressed t o t h e i r p r e s e n t s u c c e s s f u l economic s t a t u s i f t h e i r knowledge of t h e f e e d i n g requi rements of those animals were as l i m i t e d as o u r s i n r e l a t i o n t o mol lusks .

It would be a m i s t a k e , however, t o a s c r i b e t h e r e l a t i v e l a c k o f p r o g r e s s i n mol luskan fa rming and r e s e a r c h d u r i n g t h e l a s t 50 y e a r s s o l e l y t o t h e absence of i n i t i a t i v e o r d r i v e among b i o l o g i s t s working i n t h e s e f i e l d s . U n t i l about 25 y e a r s ago most of t h e s e people were working w i t h i n ex t remely l i m i t e d budgets .

Because c o n d i t i o n s f o r advancing molluskan farming have be- come more f a v o r a b l e d u r i n g r e c e n t y e a r s , p r i n c i p a l l y due t o t h e b e t t e r a t t i t u d e of f i s h e r y a d m i n i s t r a t o r s towards t h i s f i e l d , and because more money and t a l e n t a r e a v a i l a b l e now t o e x p e d i t e much needed r e s e a r c h , t h e q u e s t i o n n a t u r a l l y i s what d e f i n i t e a s p e c t s of m a r i c u l t u r e m e r i t o u r immediate a t t e n t i o n . Although I have d i s - cussed t h i s s u b j e c t b r i e f l y (Loosanoff , 1972) , I s t i l l f e e l t h a t c e r t a i n p o i n t s should be re-emphasized and brought a g a i n t o t h e a t t e n t i o n of m a r i c u l t u r i s t s . I s h a l l c o n f i n e myself on ly t o t h o s e t h a t should be a c t e d upon a s soon as p o s s i b l e .

DETOXIFICATION OF MOLLUSKS

One of t h e most s e r i o u s and u r g e n t t a s k s which f a c e s m a r i c u l - t u r i s t s , worldwide, i s t h a t of d e v e l o p i n g r a p i d , s imple , and i n - e x p e n s i v e methods $?or d e t o x i f i c a t i o n o f mol lusks which may c o n t a i n p a r a l y t i c s h e l l f i s h poison (P.S.P.) . T h i s t y p e of po isoning i s caused c h i e f l y by e a t i n g b i v a l v e s which have been f e e d i n g on d i f - f e r e n t s p e c i e s o f d i n o f l a g e l l a t e s be longing t o t h e genus of Gonyaulax, o r i n some i n s t a n c e s on r e l a t e d p l a n k t o n i c forms. E x c e l l e n t rev iews of t h e problem of p a r a l y t i c s h e l l f i s h poisoning

Problems of Molluskan Farming 34 3

were o f f e r e d r e c e n t l y by Quayle, 1969, and Prakash, e t a l . , 1971. The organism r e s p o n s i b l e f o r t h e accumula t ion o f P.S.P. i n s h e l l - f i s h of our P a c i f i c Coast i s Gonyaulax c a t e n e l l a , w h i l e Gonyaulax tamarens is i s t h e c a u s a t i v e organism of t h e A t l a n t i c Coast . Recent ly g. t a m a r e n s i s h a s been suspec ted of c a u s i n g outbreaks of P.S.P. i n s e v e r a l a r e a s of Europe, namely S c o t l a n d , P o r t u g a l , Norway, and B r i t a i n (Pzakash, e t a l . , 1971) .

Both g. t a m a r e n s i s and g. c a t e n e l l a may be p r e s e n t i n t h e water wi thout c r e a t i n g d e f i n i t e blooms but s t i l l be s u f f i c i e n t l y numerous t o r e n d e r some s p e c i e s o f s h e l l f i s h poisonous. By con- t r a s t , even s t r o n g l y pronounced blooms, o f t e n c a l l e d "red water , " may not be c a u s i n g t o x i c i t y of e d i b l e mol lusks .

D i n o f l a g e l l a t e blooms, some o f which may be poisonous, a r e o f wide occurrence and have appeared i n many a r e a s both nor th and south o f t h e e q u a t o r . These phenomena were r e p o r t e d long ago (Vancouver, 1798). It i s i n t e r e s t i n g t h a t one of t h e ea r ly w r i t t e n r e p o r t s was by C h a r l e s Darwin i n 1832 d u r i n g h i s voyage of H.M.S. Beagle a l o n g t h e c o a s t o f C h i l e .

Mass m o r t a l i t i e s o f o y s t e r s and mussels were r e p o r t e d i n 1891 i n A u s t r a l i a n w a t e r s n e a r Por t Jackson due t o "red water," probably caused by blooming d i n o f l a g e l l a t e s . Japanese r e c o r d s a l s o pro- vide numerous o u t b r e a k s o f "red water" which o f t e n k i l l e d l a r g e q u a n t i t i e s o f f i s h and s h e l l f i s h .

On our P a c i f i c Coast d i s c o l o r a t i o n o f c o a s t a l w a t e r s from Santa Barbara t o San Diego h a s been r e p o r t e d on many occas ions . Occurrence o f Gonyaulax i n t h e w a t e r s o f c e n t r a l and n o r t h e r n C a l i f o r n i a , and e x t e n d i n g a l l t h e way t o Alaska, i s a l s o f requent . A t t h e p r e s e n t t i m e t h e f i s h a u t h o r i t i e s of C a l i f o r n i a , Oregon, Washington, Alaska , and B r i t i s h Columbia cont inuous ly monitor con- d i t i o n s o f t h e water and s h e l l f i s h d u r i n g summer months. Normally t h e season f o r some e d i b l e b i v a l v e s , e s p e c i a l l y musse ls , i s c losed during t h e p e r i o d when g. c a t e n e l l a i s p r e s e n t . The problem of c losed seasons i s , however, c o n s i d e r a b l y complicated because some mollusks, such as t h e b u t t e r clam (Saxidomus g i g a n t e u s ) may r e t a i n the poison accumulated from e a t i n g t o x i c d i n o f l a g e l l a t e s f o r more than a y e a r (Quayle, 1969).

I n a d d i t i o n t o many f i l t e r - f e e d i n g b i v a l v e s t h a t accumulate toxin from f e e d i n g upon poisonous d i n o f l a g e l l a t e s , some gastropods may s t o r e t o x i n i n t h e i r b o d i e s , e s p e c i a l l y i n t h e d i g e s t i v e gland. S e v e r a l o f t h e s e , such as s o - c a l l e d rough whelks (Buccinum undatum) a l a r g e c a r n i v o r o u s s n a i l , have d e f i n i t e l y been found respons ib le f o r i l l n e s s e s and even m o r t a l i t y i n humans due t o P.S.P. (Prakash, e t a l . , 1971). High l i g h t i n t e n s i t y and r e l a t i v e l y high water t e m p e r a t u r e s , combined wi th calm weather , a r e u s u a l l y favor- able f o r t h e p r o l i f e r a t i o n o f t h e s e d i n o f l a g e l l a t e s . Thus, genera l ly , t h e massive appearances of both G. t amarens is and G. c a t e n e l l a a r e summer phenomena.

344 WORLD MARICULTURE SOCIETY WORKSHOP

Some b i v a l v e s , e s p e c i a l l y musse ls , accumulate poison more r a p i d l y t h a n o t h e r s o f t h e same area. The degree of accumula t ion of t h e t o x i n u s u a l l y i s i n d i r e c t r e l a t i o n t o t h e abundance of t h e poisonous d i n o f l a g e l l a t e s . The r a t e of e l i m i n a t i o n of t h e t o x i n a l s o v a r i e s a g r e a t d e a l w i t h t h e s p e c i e s . Mussels go through t h i s p r o c e s s i n a compara t ive ly s h o r t t i m e , bu t o t h e r forms may remain t o x i c t h e y e a r around.

Perhaps t h e b e s t example of t h e s e r i o u s n e s s o f t h e o c c u r r e n c e of d i n o f l a g e l l a t e s r e s p o n s i b l e f o r r e n d e r i n g mol lusks t o x i c was l a s t summer a l o n g t h e A t l a n t i c Coas t o f North America. The t o x i c "red t i d e , " caused p r i n c i p a l l y by r a p i d p r o l i f e r a t i o n o f G. E- r e n s i s a l o n g t h e N e w England Coas t e a r l y i n September o f 1972, p e r s i s t e d u n t i l approximate ly September 25th when it v i r t u a l l y d i s a p p e a r e d , even though some c e l l s of Gonyaulax were s t i l l p r e - s e n t i n t h e water (James E . Hanks, p e r s o n a l communication). I n t h e United S ta t e s t h e a r e a s a f f e c t e d inc luded Maine, N e w Hampshire, and Massachuse t t s .

A l l b i v a l v e s and most of t h e e d i b l e gas t ropods were suspec ted of h a r b o r i n g P.S.P. The s o f t - s h e l l clam (* a r e n a r i a ) and t h e mussel (Myt i lus e d u l i s ) were cons idered most dangerouk. On Septem- b e r 1 5 t h an embargo was p laced by t h e s h e l l f i s h a u t h o r i t i e s o f Massachuse t t s on h a r v e s t i n g and s a l e of hard clams, s o f t - s h e l l c lams, s u r f c lams, s c a l l o p s , and musse ls . Other N e w England c o a s t a l s ta tes took s i m i l a r p r e c a u t i o n a r y s t e p s .

Approximately 20 c a s e s of p a r a l y t i c s h e l l f i s h poisoning were r e p o r t e d d u r i n g t h e middle o f September. The exc i tement c r e a t e d by r a d i o , t e l e v i s i o n and p r e s s r e p o r t s on t h e appearance o f t o x i c d i n o f l a g e l l a t e s and t h e danger of e a t i n g s h e l l f i s h immediately and r a d i c a l l y a f f e c t e d t h e i n d u s t r y . H a r v e s t i n g of mol lusks was d i s - cont inued , t h u s a f f e c t i n g t h e l i v e l i h o o d of many people , i n c l u d i n g s h e l l f i s h p r o c e s s o r s , d i s t r i b u t o r s , and r e t a i l e r s . Seafood res- t a u r a n t s exper ienced s e v e r e l o s s e s , and even s a l e s and consumption o f c r u s t a c e a n s , such as c r a b s and l o b s t e r s , and a l s o f i n - f i s h , were a f f e c t e d .

The g e n e r a l p u b l i c was so thoroughly f r i g h t e n e d and confused by t h e unfavorable p u b l i c i t y t h a t it was expec ted t o t a k e cons id- e r a b l e t i m e b e f o r e people , normally u s i n g s h e l l f i s h as a p a r t o f t h e i r d i e t , would a g a i n b e g i n t o e a t mol lusks . For example, t h e Howard Johnson Company, one o f t h e most famous seafood r e s t u a r a n t c h a i n s of N e w England, exper ienced a 50% drop i n t h e i r sales. The a c u t e s i t u a t i o n r e s u l t e d i n t h e s ta tes of Massachuse t t s and Maine be ing proclaimed d i s a s t e r areas. (James E. Hanks, p e r s o n a l communication).

This r e c e n t ou tbreak o f P.S.P. i n New England i l l u s t r a t e s remarkably w e l l t h e danger t o s h e l l f i s h e r i e s . This danger be- comes even more s e r i o u s i f i t i s taken i n t o c o n s i d e r a t i o n t h a t f a n n i n g of b i v a l v e s , e s p e c i a l l y musse ls , i s becoming a r a p i d l y - growing a q u a t i c i n d u s t r y throughout t h e world. I n Vigo, S p a i n , mussel f a n n i n g has i n c r e a s e d from l i m i t e d p r o d u c t i o n t o hundreds

Problems o f Molluskan Farming 345

of thousands of i n c u l t i v a t i n g t i l l u s t r a t i o n o f

t o n s p e r y e a r . The r i s i n g i n t e r e s t i n New Zealand : h e i r g r e e n mussel (Perna c a n a l i c u l u s ) i s another p r o g r e s s i n t h i s branch o f m a r i c u l t u r e . Moreover,

t h e r e are reasons t o b e l i e v e t h a t w i t h i n a few y e a r s t h e Japanese w i l l a l s o t r y t o deve lop i n t e n s i v e c u l t i v a t i o n o f s e v e r a l s p e c i e s of mussels as a new s o u r c e o f animal p r o t e i n . Cons ider ing t h e frequency o f t h e appearance.of.Gonyaulax, and p o s s i b l y o t h e r t o x i c forms, i n p r e s e n t l y u t i l i z a b l e a r e a s o f mol luscan farming, t h e s o l u t i o n o f t h i s problem d e s e r v e s a n e a r l y , i f n o t t h e f i r s t , p r i o r i t y on o u r l i s t .

True, methods f o r m o n i t o r i n g t h e o c c u r r e n c e o f dangerous d i n o f l a g e l l a t e s i n seawater have a l r e a d y been worked o u t and are q u i t e dependable (Prakash , e t a l . , 1971). T h i s , however, i s not a s o l u t i o n o f t h e problem; i t i s merely a s t e p t o p r o t e c t t h e pub- l i c , w h i l e t h e l i v e l i h o o d o f s h e l l f i s h fa rmers remains unpro tec ted . I n o t h e r words, so long as t h e musse ls , clams, and sometimes even o y s t e r s , remain t o x i c , t h e y cannot and should not be s o l d . There- f o r e , a real s o l u t i o n should c o n s i s t o f f i n d i n g a p r a c t i c a l method by means o f which t h e t o x i c mol lusks c a n be q u i c k l y and completely d e t o x i f i e d .

A t t h i s t i m e it may appear t o be i m p r a c t i c a l and t e c h n i c a l l y d i f f i c u l t t o deve lop a method f o r d e t o x i f i c a t i o n o f l a r g e volumes of poisonous mol lusks . Nevertheless ' , w e may s o l v e t h i s problem i f we wholehear ted ly d i r e c t o u r e f f o r t s toward t h i s goa l . It should be p o s s i b l e because w e a l r e a d y know t h e formula of t h e t o x i n and some o f i t s p h y s i c a l and chemical p r o p e r t i e s (Schantz , 1960; Schantz, e t a l . , 1966) . Moreover, it h a s been demonstrated t h a t P.S.P. as a compound can be comple te ly d e t o x i f i e d by c e r t a i n chem- i c a l approaches (Chin, 1970) . Recent ly P r i c e and Lee (1972 a and 1972 b ) have shown t h a t p a r a l y t i c s h e l l f i s h poison i s c l o s e l y re- la ted t o p a r t i c l e s o f melanin found i n t h e s i p h o n o f b u t t e r clams (Saxidomus g i g a n t e u s ) and t h a t c e r t a i n c a t i o n s , as f o r example Al*, may s i g n i f i c a n t l y d e c r e a s e P.S.P. bound by melanin. S a l t s o l u t i o n s c o n t a i n i n g 0.01-M Al-H+, M g f t , Caw, Ba+, Na+, o r K+ induced t h e d e s o r p t i o n o f P.S.P. bound t o melanin by 5 4 , 3 4 , 2 8 , 19, 11 and 4% r e s p e c t i v e l y .

One o f t h e s t a n d a r d methods f o r t r e a t m e n t of mollusks going t o market from s u s p e c t e d w a t e r areas may c o n s i s t merely i n keep- ing them i n l a r g e t a n k s c o n t a i n i n g a d e t o x i f i c a t i n g s o l u t i o n , t h e nature o f which w i l l n o t i n t e r f e r e w i t h t h e normal water pumping of t h e t r e a t e d mol lusks . P o s s i b l y a n a d d i t i o n o f p l a n k t o n i c food organisms may r e n d e r t h e t r e a t m e n t more e f f i c i e n t because t h e ingested ce l l s w i l l c a r r y a l o n g t h e s u b s t a n c e t h a t changes t h e chemistry o f P.S.P. I s t r o n g l y b e l i e v e t h a t t h e importance of t h i s problem, which i n v o l v e s n o t on ly s a f e t y t o human h e a l t h but also t h e s a f e t y and f u t u r e p r o g r e s s o f molluskan f a n n i n g a l l over the world, r e q u i r e s t h a t a ser ies of s t u d i e s be under taken a s soon as p o s s i b l e , and o n a l a r g e scale.

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FEEDING OF COMMERCIAL MOLLUSKS

The second problem t h a t needs t o be a t tacked most energe t - i c a l l y concerns our lack of knowledge on many a spec t s of feeding c m e r c i a l mollusks, e s p e c i a l l y t h e i r n u t r i t i o n a l requirements. This l ack of fundamental knowledge i s preva len t even wi th our most va luable mollusk i n t h e world, t h e American o y s t e r (Crassos t rea v i rg in i ca ) ,no t t o mention t h e ma jo r i ty of t h e o t h e r b iva lves (Loosanoff, 1971, 1972). My opin ion i s s u b s t a n t i a t e d by r e f e r r i n g t o t h e b ib l iography of o y s t e r s (Joyce, 1972) which shows t h a t even i n t h e case of t h a t group we have only a fragmentary knowledge regard ing t h i s sub jec t .

It should be c l e a r t h a t , as i s done i n animal husbandry, no s u b s t a n t i a l p rogress can be made i n molluskan farming u n t i l s u f f i - c i e n t knowledge i s acqui red concerning feeding requirements of t hese organisms, i nc lud ing physiology of d i g e s t i o n and a s s i m i l a t i o n of d i f f e r e n t foods. In a g r i c u l t u r e t h i s has been accomplished because v i r t u a l l y every count ry , and i n t h e United S t a t e s almost every s t a t e , main ta ins r e sea rch c e n t e r s t h a t work cont inuous ly on these problems, dev i s ing b e t t e r food formulas, i nc lud ing even those t h a t con ta in necessary pharmaceuticals t o c o n t r o l ep izoo t i c s .

I n sharp c o n t r a s t t o t h i s , I know of no c e n t e r s of t h i s type i n mar i cu l tu re , even though t h e r e have been e f f o r t s t o feed oys t e r s wi th corn s t a r c h and o t h e r m a t e r i a l s (Ga l t so f f , 1964; Haven, 1965; Dunathan, e t a l . , 1969). A t p re sen t , however, I a m not aware of any so-ca l led "break through" d i scove r i e s t h a t would r e a l l y he lp t o f a t t e n o y s t e r s o r o t h e r b iva lves by a r t i f i c i a l means. Y e t , a s s t u d i e s a t t h e Nat iona l Marine F i s h e r i e s Se rv ice Laboratory a t Mi l ford , Connect icu t , demonstrated, it was poss ib l e t o l e a r n much w i t h i n a r e l a t i v e l y s h o r t t ime about feeding r e - quirements of molluskan l a r v a e by employing a series of wel l - designed experiments (Loosanoff, 1954; Davis and Gu i l l a rd , 1958; Loosanoff and Davis, 1963).

Even though t o d a t e no food formulas u s e f u l t o molluskan farmers have been found, t h i s does not necessa r i ly i n d i c a t e unusual d i f f i c u l t i e s i n so lv ing t h i s problem but merely sugges ts , i n my opin ion , a d e f i n i t e l ack of e f # o r t . With modern technology it should not be d i f f i c u l t t o develop mixtures c o n s i s t i n g of d i f f e r - e n t i ng red ien t s acceptab le t o j u v e n i l e and a d u l t mollusks. Pro- mising r e sea rch i n a s i m i l a r f i e l d i s now c a r r i e d on by s e v e r a l groups, i nc lud ing Meyers and h i s a s s o c i a t e s a t Louisiana S t a t e Univers i ty who a r e determining food requirements of shrimps and are developing food formulas t o meet them. 1971; Meyers, et a l . , 1971). Probably some h igh ly pulver ized p repa ra t ions composed of p a r t i c l e s measuring only a f e w microns may be u t i l i z e d bi f i l t e r - f e e d e r s . We may a l s o f i n d food formulas t h a t w i l l h e lp t o r a i s e j u v e n i l e and a d u l t abalones and some o t h e r commercially u t i l i z a b l e gastropods.

(Meyers and Rutledge,

Problems o f Molluskan Fanning 347

MOLLUSKAN EPIZOOTICS

Molluskan e p i z o o t i c s and t h e i r c o n t r o l i s a n o t h e r problem of world-wide s i g n i f i c a n c e . They occur f r e q u e n t l y and are o f t e n h i g h l y d e s t r u c t i v e ( G a l t s o f f , 1964; Sindermann and Rosenf ie ld , 1967). For example, i n a compara t ive ly r e c e n t e p i z o o t i c caused by a pro tozoan , Minchin ia n e l s o n i , u p t o 90% of marke tab le o y s t e r s d ied w i t h i n a few months i n t h e mid-At lan t ic s ta tes . Y e t , wi th t h e e x c e p t i o n o f t h e N a t i o n a l Marine F i s h e r i e s S e r v i c e Laboratory a t Oxford, Maryland, which h a s been r e s p o n s i b l e f o r much of our newly acqui red knowledge i n t h e f i e l d of molluskan d i s e a s e s , t h e r e i s v i r t u a l l y no o t h e r i n s t i t u t i o n whose e f f o r t s are c h i e f l y de- voted t o t h e s t u d i e s of m o r t a l i t y o f commercial i n v e r t e b r a t e s , even though t h e r e are i n d i v i d u a l s and s m a l l groups of s c i e n t i s t s who pursue t h e s e s t u d i e s i n s e v e r a l s t a t e and u n i v e r s i t y l a b o r a t o r i e s .

W e u r g e n t l y need more w e l l - s t a f f e d and wel l - funded s c i e n t i f i c c e n t e r s t o c a r r y on badly needed r e s e a r c h t h a t may e v e n t u a l l y g i v e u s t h e methods o f n o t only c o n t r o l l i n g but a l s o prevent ing d i s e a s e s of s h e l l f i s h . I n t h e United S t a t e s , i n my opin ion , t h e F e d e r a l Government should m a i n t a i n a t . least t h r e e major c e n t e r s of t h i s n a t u r e , one l o c a t e d on t h e A t l a n t i c Coas t , a n o t h e r i n t h e Gulf o f Mexico, and t h e t h i r d i n t h e S t a t e of Washington on t h e P a c i f i c Coas t .

Labora tory personnel o f t h e c e n t e r s should moni tor c o n d i t i o n s of i n v e r t e b r a t e f i s h e r y r e s o u r c e s , l o o k i n g f o r t h e occurrence and outbreaks o f d i s e a s e d organisms. S imul taneous ly , every e f f o r t should be made t o deve lop methods t o c o n t r o l e p i z o o t i c s . These methods may i n c l u d e u s e of chemica ls , provided it i s p e r m i s s i b l e t o do so under a g iven set of envi ronmenta l c o n d i t i o n s . S t r o n g e f f o r t s should a l s o be d i r e c t e d toward t h e development o f d i s e a s e - r e s i s t a n t r a c e s , as i s now be ing t r i e d on a l i m i t e d scale f o r t h e American o y s t e r (C. v i r g i n i c a ) i n some o f our A t l a n t i c Coast l a b o r a t o r i e s (Longwell and S t i l e s , 1970; Longwell, 1971).

It i s d e s i r a b l e t h a t , i n a d d i t i o n t o t h e United S t a t e s , o t h e r c o u n t r i e s e s t a b l i s h s i m i l a r r e s e a r c h c e n t e r s , and t h a t a l l t h e s e i n s t i t u t i o n s work i n c l o s e coopera t ion . Only by i m i t a t i n g t h e s t e p s used f o r r a p i d and g e n e r a l p rogress i n a g r i c u l t u r e may we hope t o p l a c e m a r i c u l t u r e on a f i r m foundat ion.

During t h e l as t few y e a r s I have served as a c o n s u l t a n t t o t h e S t e e r i n g Comnit tee , P a c i f i c Coas t Oys ter M o r t a l i t y I n v e s t i g a - t i o n s , formed under t h e a u s p i c e s o f t h e N a t i o n a l Oceanic and Atmospheric A d m i n i s t r a t i o n . I n t h i s c a p a c i t y I came i n c o n t a c t wi th many people d e a l i n g w i t h d i s e a s e s of commercial mollusks. I was a l s o faced w i t h t h e o l d problem o f i n t r o d u c t i o n o f e x o t i c s p e c i e s and t h e danger i n h e r i t e d i f such i n t r o d u c t i o n s a r e c a r r i e d on w i t h o u t t a k i n g c e r t a i n p r e c a u t i o n s . As a n i l l u s t r a t i o n , many of u s are aware o f what happened t o t h e s h e l l f i s h i n d u s t r y o f Holland when C r e p i d u l a f o r n i c a t a w a s brought a long w i t h shipments of American o y s t e r s . It m u l t i p l i e d so r a p i d l y and spread SO

348 WORLD MARICULTURE SOCIETY WORKSHOP

widely t h a t it almost smothered t h e o y s t e r s and some o f t h e mussel beds, no t only i n Holland but a l s o i n o t h e r European coun t r i e s (Korringa, 1951).

Large annual shipments of Japanese seed o y s t e r s (Crassos t rea g i n a s ) p lan ted i n waters of our P a c i f i c Coast, r e s u l t e d i n t h e in t roduc t ion of many undes i r ab le s p e c i e s , inc luding o y s t e r d r i l l s , f l a t worms, and crus taceans which a r c enemies of o y s t e r s and many o t h e r b iva lves . Shipments of our A t l a n t i c coas t oys t e r s t o t h e waters of t h e P a c i f i c Coast a l s o contained many undes i r ab le forms, i nc lud ing a most d e s t r u c t i v e d r i l l , Urosalpinx c ine rea , flatworms, and bor ing sponges.

I n a d d i t i o n t o t h e i n t r o d u c t i o n of enemies of mollusks by t r a n s p l a n t s from one a r e a t o another , t h e r e i s s u f f i c i e n t evidence t o show t h a t s e v e r a l o y s t e r d i s e a s e s have a l s o been spread i n t h i s manner. This i n d i c a t e s , t h e r e f o r e , t h a t haphazard, unsupervised in t roduc t ion of e x o t i c s p e c i e s should be stopped. In s t ead , i n t r o - duc t ions should be made only wi th t h e knowledge and under super- v i s i o n of b i o l o g i s t s of t h e r e spec t ive a reas , us ing methods t h a t would prevent spread of p reda to r s , compet i tors , o r d i s e a s e s (Loosanoff, 1972). Long-term quarant ine of a d u l t s and juven i l e s must be a p r e r e q u i s i t e i n a l l cases because even though they may be hea l thy they s t i l l may be ca r ry ing on o r w i th in t h e i r s h e l l s some dangerous organisms. Theore t i ca l ly , it i s even poss ib l e t o in t roduce i n such a way t h e h ighly undes i r ab le t o x i c d i n o f l a g e l l a t e - G. tamarensis from waters of t h e A t l a n t i c i n t o t h e s h e l l f i s h - producing a reas of our P a c i f i c Coast. This i n t roduc t ion may occur e i t h e r by b r ing ing l i v i n g organisms t h a t su rv ive shipment o r by t h e i r spores which, accord ing t o Prakash, e t a l . (1971), a r e formed where t h e masses of G. t amarens is d i sappear from t h e water l a t e i n t h e f a l l , which i s t h e usua l t i m e f o r o y s t e r shipments from t h e A t l a n t i c t o t h e P a c i f i c coas t . The same reasoning may be appl ied t o t h e p o s s i b i l i t y of i n t roduc t ion of G. c a t e n e l l a from our P a c i f i c Coast t o t h e waters of t h e A t l a n t i c . What would r e s u l t i s d i f f i c u l t t o p r e d i c t , bu t c e r t a i n l y such b i o l o g i c a l acc iden t s should cons iderably complicate t h e a l ready d i f f i c u l t problem of p a r a l y t i c s h e l l f i s h poisoning.

I want t o emphasize t h a t I am not opposed t o t h e in t roduc t ion of promising e x o t i c spec ie s . A predominate ma jo r i ty of p l a n t s and animals which w e use a s food i n t h e United S t a t e s were i n t r o - duced from o t h e r con t inen t s o r i s l a n d s . Personal ly , I w a s involved i n br inging two spec ie s t o our waters. The f i r s t was t h e European o y s t e r (Ostrea e d u l i s ) brought t o t h e United S t a t e s from Holland i n 1949 (Loosanoff, 1955). The in t roduc t ion was made wi th t h e knowledge and permission of American a u t h o r i t i e s . A t p resent 0. e d u l i s i s we l l e s t a b l i s h e d i n waters of t h e S t a t e of Maine. P r i o r go shipment, t h e o y s t e r s were examined and t r e a t e d by D r . P e t e r Korringa, t h e recognized s h e l l f i s h a u t h o r i t y o f Europe, by be ing immersed i n a s o l u t i o n of o rgan ic s a l t of mercury s u f f i c i e n t l y s t r o n g t o k i l l t h e organisms l i v i n g both w i t h i n t h e s t r u c t u r e of t h e o y s t e r s h e l l s and on t h e i r o u t s i d e su r - faces . These included organisms r e spons ib l e f o r so-ca l led

Problems of Molluskan Farming 349

"she l l -d isease ," and a l s o a l l t h e a l g a e a t tached t o t h e oys t e r s h e l l s , i nc lud ing Codium f r a g i l e .

The second mollusk, introduced more r ecen t ly , i s t he so- c a l l e d green mussel (Perna cana l i cu lus ) which we brought from N e w Zealand i n October, 1971. This i n t roduc t ion was made, of course, wi th t h e knowledge and approval of t h e S t a t e of Ca l i fo rn ia and New Zealand f i s h e r y a u t h o r i t i e s . The mussels were placed upon a r r i v a l i n quarant ine i n troughs of running seawater a t t h e P a c i f i c Marine S t a t i o n of t h e Univers i ty of t he P a c i f i c , located near Tomales Bay, Ca l i fo rn ia . A l l water t h a t e n t e r s these troughs i s discharged i n a s p e c i a l dry-well loca ted more than 1500 f e e t from t h e shore. This method prevents i n t roduc t ion of undes i rab le organisms t h a t may have come wi th t h e mussels.

I s t rong ly support formation of n a t i o n a l and i n t e r n a t i o n a l committees t o d e a l wi th in t roduc t ions of e x o t i c spec ie s throughout t he world. These groups should develop as soon a s poss ib le bas i c r u l e s and r egu la t ions aimed a t prevent ing unnecessary spreading of d i seases , p a r a s i t e s , competitors, and o t h e r undes i rab le forms, poss ib ly even d i f f e r e n t spec ie s of Gonyaulax.

OTHER NEEDS

The f i r s t need i s t o r e v i s e our S t a t e and Federa l laws and r egu la t ions so t h a t fns tead of p re sen t ing obs t ac l e s t o maricul- t u r i s t s , they a i d t h e i r a c t i v i t i e s . This i s not a simple matter, however, as has been i l l u s t r a t e d by t h e r ecen t attempt t o grow salmon i n s p e c i a l cages i n h g e t Sound. According t o Pacey (1972): "The S t a t e of Washington had t o pass a s p e c i a l r egu la t ion on s a l - mon aquacul ture before Domsea could use Puget Sound. Although v ice-pres ident Jon Lindberg (son of t h e famed a v i a t o r ) i s a l s o chairman of t h e execut ive committee of t h e S t a t e ' s Oceanographic Commission, t h e concern had t o ob ta in numerous permits and l i censes , inc luding a shore l i n e management permit. The l a t t e r was i ssued by t h e S t a t e Department of Ecology a f t e r approval by the U. S. Navy and s i x s t a t e agencies (E.P.A., I n t e r i o r , Commerce, Natural Resources, F i s h e r i e s , and Ki t sap County), Also required were such i tems a s a cons t ruc t ion permit from t h e U. S. Corps of Engineers, and a wholesale f i s h d e a l e r s ' l i c e n s e from t h e Bureau of F i s h e r i e s .It Obviously, such complexity of laws and regula t ions discourages people from e n t e r i n g t h e f i e l d of mar icu l ture . Radical changes t o amel iora te t h i s s i t u a t i o n are u rgen t ly needed.

The f i n a l po in t t o emphasize i s t h a t mar icu l ture , e spec ia l ly molluskan farming, needs leaders . A t p resent , co l l ege graduates who a r e broadly t r a i n e d i n mar i cu l tu re a r e few s ince most of t he i n s t i t u t i o n s of h igher l ea rn ing i n t h e United S t a t e s g ive l i t t l e or no a t t e n t i o n t o t h i s branch of aqua t i c sc ience . t h e i r c l e a r l y p r a c t i c a l na tu re , o f f e r i n g of courses i n mar icu l ture i s discouraged by some f a c u l t y members who s t i l l th ink t h a t only research of a pure ly t h e o r e t i c a l value should be c a r r i e d on by i n s t i t u t i o n s of h igher learn ing .

Because Of

350 WORLD MARICUL'IURE SOCIETY WORKSHOP

Regardless of t h e l ack of support and unders tanding of our a i m s , t h i s i s t h e t i m e when we should begin t o t h i n k i n terms of e s t a b l i s h i n g s p e c i a l schools where f u t u r e a q u a c u l t u r i s t s can be t r a ined . Such schools , wi th courses r equ i r ing approximately s i x o r seven years , can f u l f i l l t h e urgent need f o r i nd iv idua l s wi th broad t r a i n i n g and background t o be employed by indus t ry , s t a t e , f e d e r a l , and even i n t e r n a t i o n a l a u t h o r i t i e s . (Paul ik , 1968; McHugh, 1968). I s t rong ly suggest t h a t we m a r i c u l t u r i s t s , who a r e a l r eady working i n t h i s f i e l d , should i n s i s t t h a t i n i t i a l s t e p s f o r c r e a t i n g such c e n t e r s of t r a i n i n g be taken imnediately.

ACKNWEDGEMENTS

I want t o thank D r . James E. Hanks, D i r e c t o r of t h e National Marine F i s h e r i e s Se rv ice Laboratory of Mi l ford , Connecticut, f o r provid ing m e wi th t h e informat ion concerning t h e occurrence of t h e "red t i d e " along t h e New England Coast du r ing t h e s u m e r of 1972. I a l s o thank Mrs. Alva H. Olson f o r h e r h e l p i n t h e p repa ra t ion of t h i s manuscript .

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