Seasonal Changes in Seawater Adaptability of the Hatcery Reared Juvenile Salmon, Oncorhycunsus Nerka

8/14/2019 Seasonal Changes in Seawater Adaptability of the Hatcery Reared Juvenile Salmon, Oncorhycunsus Nerka

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* b d>@?%, Sci. Rep. Hokkaido Salmon Hatchery, ( 45 ) : 25-33 (1991)

Seasonal Changes in Seawater Adaptability of the Hatchery RearedJuvenile Sockeye S a lm o n , Oncorhynchus nerka

M a s a t o s h i BAN*' a n d K o h e i YAMAUCHI* '

AbstractS e a w a t e r (33 ~) cha l l enge t e s t was pe r formed to a s ses s the deve lopment of s eawate r

a d a p t a b i l it y i n t h e u n d e r y e a rl i n g a n d y e a r l i n g so c ke y e s a l m o n , Oncorhynchus nerha f r o mJuly, 1989 to July, 1990. The body s i lvering were observed throughout the experimentalpe r iod , whereas the p igmenta t ion of b o t h d o r s a l a n d t a i l f i n m a r g i n s a p p e a r e d d u r i n gf rom Ju ly to Oc tober , 1989 , and f rom M ay to June, 1990. A surviv al ra te of 100% wasobse rved on the 7 th d ay a f t e r t r ans fe r in to s eawate r in Augus t and September 1989 , an din May and June , 1990. Se rum sod ium conten t s a f t e r t he 7 th day of t r ans fe r in to s eawate rwere low in Augu s t and September , 1989 and J une , 1990 . H igh g i l l Na+ , K+-ATPaseact ivi ties were observed in August , 1989 and J un e, 1990. These resul ts sugge s t tha t theundery ea r l ing an d yea r l ing sockeye s a lm on deve lop s eawate r adaptab i l i t y in Augus t andin June, respect ively.

IntroductionS m o l t i f ic a t i o n ( p a r r - s m o l t t r a n s f o r m a t i o n ) i n s a l m o n i d s is a very complex phenomenon

c o m p o s e d o f m o r p h o l o g i c a l , p h y s i o l o g ic a l a n d b e h a v i o r a l c h a n g e s ( H o a r 1 9 7 6 , 1 9 8 8 ) . In g e ne -r a l , a l m o s t t h e s a l m o n i d s s m o l t i f y i n t h e r iv e r a f t e r h a t c h i n g o u t , f o ll o w ed by m i g r a t i o n tot h e s e a . D u r i n g s m o l t i f i c a t i o n , s e a w a t e r a d a p t a b i l i t y d ev e lo p e s si m u l t a n e o u s l y w i t h t h e o c c ur -r e nc e o f b o t h b o d y s i l v e r i n g a n d p i g m e n t a t i o n of d o r s a l a n d c a u d a l f i n m a r g i n s ( K u b o 1 9 8 0 ;G o r b m a n e t a l . 1 9 8 2 ; Y a m a u c hi e t al. 1984) .

S o c k e y e s a l m o n , Oncorhynchus nerha, d i s p l a y t h e m o s t v a r i e d a n d c o m p le x l i f e h i s t o r i e sw i t h i n g e n u s 0ncodz.ynchus ; t h e i r l i f e p a t t e r n s a r e c la s s if i e d i n t o t h r e e c a t e g o r i e s : sea - , r i ve r -a n d l a k e - t y p e s ( W o o d e t a l . 1 9 8 5 ) . H o w e v e r , o n l y t h e l a k e - ty p e a m o n g t h e m h a s b e en r e p o r t e di n J a p a n . R e c e n t l y , trials f o r t h e r e l ea s e o f l a k e -t y p e s o c k ey e s a l m o n h a s b ee n p e r f o r m e d i no r d e r to produce a new resource of the f i sh . To i m p r o v e t h e s u r v i v a l r a t e o f t h e f i s h , i n f o r-m a t i o n s o n t h e p h y s i o l o g ic a l c h a r a c t e r i s t i c s i n c lu d i n g t h e d e v e lo p m e n t of s e a w a t e r a d a p t a b i l i t ya r e i m p o r t a n t . T h i s p a p e r d es c r ib e s t h e s e a s o n a l c h a n g e s a c c o m p a n y i n g t h e d e v e l o p m e n t ofs e a w a t e r a d a p t a b i l i t y in ha tche ry- rea red sockeye s a lm on.

JL. iS S b dxlLEj.tiffR%@%28* Hokkaido Salmon Hatchery, Fisheries Agency of J a p a n , 2-2Nakanoshima, Toyohira-ku, Sapporo*2Faculty of Fisheries, Hokkaido Universlty, 3-1-1 Minato, Hakodate 041 JAPAN L l l l f 3 @ * : j h g A y062 JAPAN H E@ 7k&Edk&S 3 9 * b AlL~:r)

7 k E W 3 )25


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aterialsand MethodsFish : Eggs w ere obta ined f ro m adu l t sockeye sa lm on, Oncorhynchus nerka, caught in Oc tober ,

1988 f rom the Abira R iver, Hokkaido . They were t r ansfe rred to Chi tose Branch, Hokka idoSa lmon H atchery and rea red in wel l wa te r indoor ponds(7-8 C) . Af te r ha tching ou t in Jan uaryof 1989 , they were ra ised in out doo r well wa ter ponds (7-8C) under na tu ral photoperiod unt i lJu ly of the same year . The fi sh were t r ansp or ted t o anothe r outd oor pond, and were samplesmon thly unt i l Ju ly , 1990. Rear ing wa te r tempe ra ture and photoper iod dur ing the pe r iodsampled the f ish were shown in Fig. 1. Food (dry pelle t : Taiyo Jir yo ) were supplied twice aday dur ing th e exper imenta l pe r iod .

J A S O N D J F M A M J J1989 1990- I+MonthFig. 1. Seasonal changes in day length ~ ) and watertemperature . - - . - - . . . . .) from July, 1989 to J u l y , 1990.Water temperature w as expressed as mean values of each

ten days.

Seawater challenge : To de te rmine sea wate r ada pta bi l i t y , seaw ate r cha l lenge te s t were pe r for -med (Clarke and Blackburn 1 9 7 7 ) . 50-100 f ish samples collected randomly were transfe rredin to a r t i f i c i a l s e a w a te r (33%, 11.O+l.O0C>. O n t h e 1st a nd 7 th da y a f t e r t he t r a ns f e r , a f t e ranesthetiz in g using tr icaine rnethanes ulfonate (MS2221 , the ir fo rk lengths were measured (Fig.2). Blood samp les were obtained fro m th e cauda l vein using a capil lary. Gill f i l la me nts wereimm ediately r insed in ice-cold hom ogenizing solution (250 m M Sucrose, 6 m M E D T A - 2N a ; 20mM imidazole , pH 6 .8) and f rozen immersed in the so lu t io n (20 t im es volume) unt i l Na+, KP A T P a se a s sa y . Serum obtained by centrifugation at 10,000g f o r 5 min were stored at -40Cunt i l sodium content a ssay .

Serum sodium concentrations : Serum sodium concent ra t ions in f reshw ate r and seaw ate r weremeasured us ing an Atomic Absorpt ion and F lame Emiss ion Spec t romete r (Shimadzu, AA-640-1 3 .

Na, Kf-AT Pase ac tiv ity : Gil l f i l laments were homogena ted in lmk' of the above so lu t ion ,26


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Ban and Yamauchi : Seawater Adaptability of Sockeye Salmon

140E

120 -r,- 1003

80

rnC0

160 I

O J1 . 1 1 1 1 1 1 1 1 1 1 1 1J A S O N D J F M A M J J+ 1989 1990

MONTHFig. 2. Seasonal changes in fork length of hatchery-reared

sockeye salmon from July, 1989 to July, 1990. Thevertical bars represent the meaniSE.

and 40 b Le of the homogena ted was incuba ted e i the r in 160 ut? of reac t ion mix ture A ( 250m M im ida z o le , 12 . 5 m M ATP2Na, 337.5 m M NaCl , 162.5 mM KC1, 50 mM MgC12) or 160

~ f r eac t ion mixture B ( reac t ion mixture A + 2 . 5 m M o u a b a i n ) f o r 2 0 m i n a t 37 C in ashaking incuba tor . The reac t ion was s topped by adding 4 d f i ron TCA solu t ion (100 g TCA,10 g th iou r e a , 30 g f e r r ou s a nm on ium s u l f a t e i n 1 l i t e r ) , F r e e Pi was measured according tothe method of Goldenberg and Fernandez (19 66) and pro te in concent ra tions were de te rminedby the m e thod o f L ow r y e t al. (1966) .

Stat is t ica l ana lys is : The da ta presented a re expressed as m e a ns iS E M . O ne - w a y a na ly s i s o fva r iance fo l lowed by the S tudent -Newman-Keul ' s mul t ip le r ange te s t were conduc ted .

ResultsExternal appearrance : Throughou t the exper imenta l pe r iod f rom June , 1988 to June , 1990,

body s i lve r ing was observed . In con t ras t , p igm enta t i on on the dor sa l f in margins of under-ye a r l i ng a nd ye a r l i ng f i sh w a s obse r ve d f r om Ju ly t o O c tobe r ( 1989 ) a nd f r om M a y to J u n e(199O), respectively.

Surv iva l ra te in seawater : S ur v ival r a t e o f f i sh on t he 7 th da y a f t e r t r a n s f e r t o s e a w a te rwas de te rmined (Fig. 3). The surv iva l r a te s in underyearl ing f i sh were 100% in August a n dO c tobe r ( 1989 ) . T he r e a f t e r the r a t e d r oppe d t o 33 , in November , fo l lowed by low surviva lr a t e s un t i l F e b r ua r y , 1990 . In Ma rch , the sur v iva l r a te of the yea r l ing f i sh inc reased , anda t t a ine d 100% in M a y a nd June , 1990 , f o ll ow e d by d r opp ing to 51% in Ju ly .

Serum sodium contents : Serum sodium contents in underyear l ing f resh wate r f i sh showedgradu a l ly inc reas ing leve ls : f r om 12 7 . 6 t 5 . 9 m E q /C in Ju ly t o 154 .9*1 .3 m E q / t? i n O c tobe r

27


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100 -5 7 5 -al-E2- 50=I.

25

0 -

Fig.3. Seasonal changes in the survival rate on the 7thday after transfer to seawater 3 3 x 0 ) from July, 1989to July, 1990.

1 1 1 , 1 , 1 1 ) 1 , 1 ~

220 -=U.2v

O 180E8Ee 160

5 140 --Uv5 120z

FW

-O J . 1 , , 1 , , , , , , ~J A S O N D J F M A M J J

MONTH1989 1990

Fig. 4. Seasonal changes i n serum sodium concentrationsof freshwater fish (1 and seawater fish (1on the 7th day after transfer to seawater (33x0) f romJuly, 1989 to Ju ly , 1990. The vertical bars representthe mean-+SE.


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B a n a n d Y a m a u c h i :S e a w a t e r A d a p t a b i l i t y of S o c k e y e S a l m o n( 19891 , f o ll ow e d by f l uc tua t i ng va lue s be tw e e n 140 . 013 . 4 m E q / t a nd 1 55 . 2 k1 . 1 m E q / l

un t i l M a y ( F ig . 4 . In Jun e and Ju ly , 1990, the leve ls dropped aga in to 136.4+2.7 and 139.31 3 . 4 m E q /k , r e spe c tive ly . In c o n t r a s t , t he c onc e n tr a t ions of s e r um sod ium in seawate r under -ye a r li ng f i sh w er e l ow in A ugus t ( 165 .5+2 .2 m E q / t ) a nd S e p te m be r ( 169 . 5k3 . 1 m E q / t ) ,show ing good se a w a te r a da p t a b i l i t y , f o ll ow e d by a gr a du a l de cr ea se i n a da p t a b i l i t y . A f t e r t hepeaked levels in February (19901, the sodium leve ls began to decrease , and a t ta ine d lower va lue

( 1 5 7 .5 k 1 . 9 m E q / t ) in June ( 1990 ) .In underyearl ing f i sh in Au gust , 1989 and y ea r l ing f i sh in June , 1990, t ime course changes

in se rum sodium concent ra t ions were inves t iga ted on the 1s t and 7 t h d a y a f t e r t r a n s f e r t oseaw ate r (F ig . 5 ) . Se rum sodium leve ls of Augu st underyearl ing f i sh in f resh wate r was 140.9k 1 . 9 m E q /k . T he sod ium c onc e n tr a t ions i nc re a se d t o 184 . 0k3 . 9 m E qM on the 1st d a y a f t e rt r a ns f e r t o s e a w a te r , w h ic h de cr ea sed t o 165 . 5+2. 2 m E q /k on t he 7 th da y a f t e r t r a n s f e r t oseaw ate r . In con t ras t , se rum sodium concent ra t ions in June yea r l ing f i sh in f res hw ate r showed13 6.4 k2. 7 mEq/k '. The levels on the 1s t day a f te r t r a nsf e r to seawa te r inc reased to 1 6 4 . 6 k6.3 m Eq / t which were lower in compar ison wi th th a t in August underyearl ing f i sh . The sodiumlevels on t he 7 th da y a f t e r t r a n s f e r t o s e a w a te r show e d low l e vel s , 157 . 5k1 . 9 m E q / t .

Na+, K -ATPase ac t i v i t y : In the f reshw ate r f i sh , g i l l Na+, K+-ATPase ac t iv i ty peaked inA ugu s t , 1989 ( 16 . 6k 2 . 0 um o le s P i /m g p r o . /h r . ) ( F ig . 6 ) . T he r e a f t e r , t he a c t i v i t y de cr ea sedto 5 .5+0.6 um oles P i /mg pro . /hr . , and mainta ined the sam e levels (5-6 um oles P i /mg pro . /h r . ) u n t i l A p r i l ( 1 9 9 0 ) . In J u n e , t h e a c t i v i t y pe ak ed a g a i n ( 1 6 . 3 i 0 . 7 u m o l e s P i / m g p r o J h r . 1 .O n the o th e r ha nd , t he N a + , K + - A T P a se a c t i v i t y i n s e a w a te r f i sh show e d s im i l a r pa t t e r n s t o

200-WLuQ

180.-

160r0 )r

40.-,Q

E 120v

100

FW1 d i n S W

0 7 d i n S WT

AUG 1989) JUN 1990)O I+

Fig. 5. T i m e c o u r s e c h a n g e s in s e r u n i s o d i u mc o n c e n t r a t i o n s o n t h e 1 s t a n d 7 th d a y a f t e rt r a n s f e r t o s e a w a t e r (33 0) n u n d e r y e a r l i n g

( A u g u s t , 1989) a n d y e a r l i n g f i s h ( J u n e ,1990). T he ve r t i c a l bar s r e p re s e n t t h e m e a nk SE .

29


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- ]0 1 1 1 , 1 1 1 1 1 1 . 1 1 1J A S O N D J F M A M J J-@989 1990Month

Fig. 6. Seasonal changes in gil l Naf, K f - A T P a % activitiesin freshwater fish M)nd seawater f i s h (1on the 7th day after transfer to seawater (33 0). T h evertical bars represent the meankSE.

t h o s e o f f r e s h w a t e r f i s h . H o w e v e r , t h e a c t i v i t y in s e a w a t e r f i s h b e t w e en O c t o b e r ( 1 9 8 9 ) a n dA p r i l ( 1 9 9 0 ) w e re r el a t iv e l y h i g h e r ( 1 0 . 8 1 kO . 6 - 1 1 .7 1 0 . 5 f i m o l e s P i / m g p r o . /h r . ) t h a n t h o s eo f f r e s h w a t e r f i s h .

DiscussionIn g e n e r a l , s a l m o n i d s a r e k n o w n t o c h a n g e i n e x t e r n a l a p p e a m a n c e , s u ch as body s i lve r ing

a n d p i g m e n t a t i o n of t h e d o r s a l a n d c a u d al f i n m a r g i n s d u r i n g s m o l t i f i c a t i o n ( H o a r 1976,1988).In t h e p r e s e n t s t u d y , s o c ke y e s a l m o n s h o w e d b o d y si l v e r in g t h r o u g h o u t t h e e x p e r i m e n t a l p e r i o dd u r i n g b e tw e e n J u l y ( 1 9 8 9 ) a n d J u l y ( 1 9 9 0 1 , w h e r e a s p i g m e n t a t i o n of t h e d o r s a l a n d c a u d a lf i n m a r g i n s w a s o b se r ve d f r o m J u l y t o O c t o b e r, 1989, a n d f r o m M a y t o J u ne , 1990. Theoccurrence of th e p igm enta t io n co inc ided wi th the deve lop ment of s e a w a t e r a d a p t a b i l i t y w h i c hwi l l be desc r ibed in the fo l low ing d i s cus s ion . Hence , t he p igme nta t ion of dorsa l and cauda l f inm a r g i n s s e e m s to be a g o o d c r i t e r i a t o d e t e r m i n e t h e d e v e l o p m e n t of s e a w a te r a d a p t a b i l i t y i nsockeye s a lmon.

A s id e f r o m c h a n g e s i n t h e e x t e r n a l a p p e a r r a n c e , s a l m o n i d s u n d e r g o p h y s io l o g ic a l c h a n g e sd u r i n g s m o l t i f i c a t i o n . A m o n g t h e m , s e a w a t e r a d a p t a b i l i t y d ev e lo p es d u r i n g s m o l t i f i c a t i o n

( H o a r 1988). I t is r e p o r t e d t h a t g i l l N a f , K + - A T P a s e a c t i v i t y i n c re a s e s d u r i n g s m o l t i f i c a -t ion in coho salmon (Zaugg and Wagner 1973 ; Folmar a n d Dickhoff 19801, steelhead trout

( Z a u g g a n d M c L a i n 1 9 7 1 ) , A t l a n t i c sa l m o n ( B o eu f e t a l . 1 9 8 5 ) a n d m a s u s a l m o n (Ban e tal. 1 9 8 7 a , b ) . T h e r e f o r e , g i l l N a f , K + - A T P a s e a c t i v i t y is k n o w n t o b e o n e o f i n d i c a t o r s o ft h e d e v e l o p m e n t o f s e a w a t e r a d a p t a b i l i t y i n s a l m o n i d s ( H o a r 1 9 7 6 , 1 9 8 8 ) . I n t h e p r e s e n t s t u d y ,h igh g i l l Naf , Kf -ATPase ac t iv i t i e s were obse rved in underyea r l ing and yea r l ing f i sh , co inc idedw i t h t h e h i g h s u r v i v a l r a t e in s e a w a t e r . F u r t h e r m o r e , s e r u m s o d i u m c o n c e n t r a t i o n on t h e 7 t h3


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B a n a n d Y a m a u c h i : S e a w a t e r A d a p t a b i l i t y of S ockeye Salmona f t e r t r a n s f e r to s e a w a t e r d e c r e a s e d w i t h a c o n c o m i t a n t i n c r e a s e in t h e g i l l N a f , K+ P A T P a s ea c t i v i t i e s .

F u r t h e r m o r e , s e a w a t e r c h a l le n g e t e s t is u s e f u l t o a s s e s s t h e d e v e l op m e n t o f s e a w a t e ra d a p t a b i l i t y in s a l m o n i d s ( C l a r k e a n d B l ac k b u r n 1 9 7 7 ) . I n t h e p r e s e n t s t u d y , s e r u m s o d i u mc o n c e n t r a t i o n s w h ic h w e re i n v e s t i g a t e d 7 t h d a y a f t e r t r a n s f e r t o s e a w a t e r d e c re a se d i n ac c o r dw i t h t h e i n c r e a s e i n g i l l N a + , K A T P a s e a c t i v i ti e s . T h e r e f o r e , g i l l N a f , K+ - A T P a s e a c t i v i -t ie s , a n d s e r u m s o d iu m c o n c e n t r a t i o n s a f t e r t r a n s f e r t o s e a w a t e r s e e m to b e g o o d i n d i c a t o r st o d e t e r m i n e t h e d e v e l o p m e n t o f s e a w a t e r a d a p t a b i l i t y i n s o c k e y e s a l m o n as well as i n o t h e rs a l m o n i d s .

T h e r e su l t s o n t h e s u rv i v a l r a t e a f t e r t r a n s f e r t o s e a w a t e r , s e a w a t e r c h a l le n g e t e s t a n dg i ll N a f , Kf - A T P a s e a c t i v i t y s u g g e s t t h a t t h e s e a w a t e r a d a p t a b i l i t y d ev e lo p i n b o t h u n d e r-y e a r li n g f i s h a n d i n y e a r li n g fi s h in A u g u s t, 1 9 8 9 , a n d J u n e , 1 9 9 0 , a l t h o u g h a d a p t a t i o n tos e a w a t e r i n t h e u n d e r y e a r l i n g f i s h w a s s l i g h t l y p o o r e r , c o m p a r e d w i t h t h a t o f t h e y e a r l i n gf i sh . Baggerma n (1960) and McInerney (1964 ) desc r ibed th a t s eaw ate r p refe rence obse rved int h e s o ck ey e s a l m o n f r y a f t e r h a t c h i n g o u t w a s m a i n t a i n e d u n t i l J u n e , f o l l ow e d b y a decrease,w h i c h d e v e lo p e d a g a i n i n M a y - J u l y o f t h e f o l l o w i n g y e a r . S i m i l a r l y , i n h a t c h e r y r e a r e d s o ck e yes a l m o n , K a e r i y a m a e t al. ( 1 9 8 7 ) d e s c ri b e d t h a t y e a r l i n g f i s h s h o w e d s e a s o n a l c h a n g e s in s e a -w a t e r a d a p t a b i l i t y . T h es e f i n d in g s m a y i n d ic a t e t h a t t h e d e ve l op m e n t o f s e a w a t e r a d a p t a b i l i t yo c c u r s e a s o n a l y i n b o t h t h e u n d e r y e a r l i n g a n d y e a r l i n g f i s h .

Occur rence of s m o l t i f i c a t i o n i n s a l m o n i d s i n c l u d i n g s o c k e y e s a l m o n is j ud g ed f r o m t h ed e v e l o p m e n t o f s e a w a t e r a d a p t a b i l i t y a n d c h a n g e s i n e x t e r n a l a p p e a r a n c e ( H o a r 1 9 7 6 ) . I ng e n e r a l , a l m o s t all o f t h e s o ck e y e s a l m o n s m o l t i f y as year l ing f i sh(Mc1nerney 1964 ; K a e r i y a m ae t a l . 1987 ; W o o d e t al. 1 9 8 7 ) . A s d e sc ri b ed e a r l i e r , A u g u s t u n d e r y e a r l i n g f i s h as well as J u n ey e a r l i n g f i s h d e ve lo p e d s e a w a t e r a d a p t a b i l i t y c o n c o m i t a n t w i t h t h e p i g m e n t a t i o n o f d o r s a l a n dc a u d a l f i n m a r g i n s . S i nc e e n v i r o n m e n t a l f a c t o r s a f f e c t s m o l t i f i c a t i o n ( W e d e m e y e r e t a l . 1 9 8 0 1 ,i t s e e m s l ik e ly t h a t h a t c h e r y - r e a r e d s o ck e ye s a l m o n as u n d e r y e a r l i n g f i sh s m o l t i f y u n d e rr e a r i n g c o n d i t i o n a d o p t e d . T o a s c e r t a i n t h i s , f u r t h e r i n v e s t i g a t i o n s a r e re q u i r ed .

I n c o n cl u s io n , u n d e r a r t i f i c i a l r e a r i n g c o n d i t io n u se d i n t h e p r e s e n t s t u d y , u n d e r y e a r l i n gs o c k e y e s a l m o n m a y s m o l t i f y as well as year l ing f i sh . Thi s f ind ing m ay expla in th e occurrenceo f t h e v a r i e d a n d c o m p l e x l i f e h i s t o r i e s i n t h e s o c k e y e s a l m o n .

AcknowledgementsW e w i s h to e x p r e s s o u r a p p r e c i a t i o n t o Dr. O s a r n u H i r o i, H o k k a i d o S a l m o n H a t c h e r y f o re n c o u ra g e m e n t o f t h i s s t u d y . T h a n k s a l s o d u e t o s t a f f o f C h i t o se B r a n c h , H o k k a i do S a l m o n

H a t c h e r y f o r t h e i r e f f o r t r e a r i n g a n d s u p p l y in g t h e e x p e r i m e n t a l f i s h . T h i s w o r k w a s s u p p o r t e di n p a r t b y G r a n t - i n - A i d f r o m t h e M i n i s t r y o f E d u c a t i o n , S c ie n ce a n d C u l t u r e , a n d A g r i c u l t u r e ,F o r e s t r y a n d F i s h e r i e s R e s e a r c h C o u n c i l , t h e M i n i s t r y of A g r i c u l t u r e , F o r e s t r y a n d F i s h e r i e s ,J a p a n .

31


8/9

ReferencesRaggerman, B . (1960) : Salinity preference, thyroid activity and the sea ward mig rat ion of fou r

species of Pacific salmon (Oncorhynchus). J. Fish. Res. Bd. Can.17 (31, 295-332.Ban, M., K. Kasahara, and K . Yamauchi (1987a) : Physiological changes in the hatchery-reared

yearling mas u salmon Oncorhynchus masou) du ring smoltification. Sci. Rep. HokkaidoFish Hatchery, (42), 27-35. (in Japanese with English abstract)

Ban, M., K. Kasahara, and K. Yamauchi (1987h) : Physiological changes in the hatchery-rearedunderyearling masu salmon ( Oncorhynchm masou) during smoltification. Sci. Rep .Hokkaido Fish Hatchery. (42), 19-26. (in Japanese with English abstract)

Boeuf, G . and P. Prun et (1985): Measure ments of gi ll ( N a + - K + > -ATPase activity and plasmathyroid horm ones duri ng smoltification in Atlantic salmo n (Sa lmo salar L.) .Aquaculture,45, 111-119.

Clarke, W . C. and J. Blackhurn (1977) : A seawater challenge test to measure smolti ng in juvenilesalmon. Fish. Mar Seru. Tech. Rep. (7051, 1-11.

Folmar, L. C. and W . W . Dickhoff (1980) : The parr-smolt transformation (smoltification) andseawater adaptation in salmonids. A Review of selected literature. Aquaculture. 21, 1-37.

Goldenberg, H. and A. Fernandez (1966) : Simplified method for the estimation of inorganicphosphorus in body fluids. Clin. Chem., 12 , 871-882.

Gorbman, A., W . W.Dickhoff, J . L.Mighel1, E. F.Prentice, and F. W. Waknitz (1982): Morpho-logical indices of developmental progress in the parr-smolt coho sa lmo n, Oncorhynchuskisutch. Aquaculture. 28, 1-19.

Hoar, W . S. (1976) : Smolt transformation : evolution behavior and physiology. J . Fish. Res. BdCan. 33, 1234-1252.

Hoar , W . S. (1988) : The physiology of smolting salmonids. In Fish physiology. (W. S. Hoar andD . J . Ran dell , ed.), pp. 275-343. Academic p ress New Yor k.

Kaer iyama, M. , I . Shimizu, and H. Kakizakl (1987) : Seasonal changes in seawater adaptation ofsockeye salmon reared in the freshwater. Sci. Rep Hokkaido Salmon Hatchery, (411,129-135. (in Japanese with English abstract)

Kubo, T . (1980) : Studies on the life history of Masu salm on (Oncorhynchus masod in Hokkaido.Sci. Rep. Hokkaido S alm on Hatchery, (341, 1-95. (in Japa nese with English abs tract)

Lowry, 0 H . , N . J Rosebrough, A. L. Farr, and R. J Randa ll (1951): Protein measurementwith the Fohn phenol reagent. J. Biol. Chem., 193, 265-275.Mclnerney, J . E. (1964) : Salinity preference : an orientation mechanism in salmon migration. J.Fish. Res. Bd Can., 21 51, 995-1018.

Wedemeyer, G . A., R. I,. Saunders, and W . C. Clarke (1980) : Environmental factors affectingMarine Fisheriesmoltification and early marin e survival of anad rom ous salmonids.

Reuiew. 42 (61, 1-14.Wood, C. C . and B. E. Riddell, and P. T. Rutherfo rd(1985): Alternative juvenile life histo ries of

sockeye sal mon Oncorhynchus nerka) and their contributlon to production in the StikineRiver, Northern British Columbia. p. 12-24. In H. D . Smith, L. Margolis, and C. C . Wood

(ed.) Sockeye salmon ( Oncorhynchus nerka) population biology and future management.32


9/9

Ban and Yamauchi : Seawater Adaptability 0f SOckeye SalmonCan. Spec. Pub1. Fish. Aquat. Sci., 96.

Yamauchi, K., N. KOide, S. Adachi, and Y. Nagahama 1984): Changes fn seawater adaptabilityand b100d thyroxine concentrations during smoltification Of the masu salmon, Oncorhyn-chus mason, and amago salmon, Oncorhynchus rhodu.rus. Aquaculture, 42, 256-274.

Zaugg, W. S. and L. R. McLain 1971): Changes In gill ATPase activity associated with parr-smolt transformation fn steelhead trout (Salmo gairdneri), coho salrnon (Oncorhynchuskisutch) and spring chino0k salmon (0. tshawytscha.) J. Fish. Res. Bd. Can. 19, 167-171.

Zaugg, W. S. and H. I1. Wagner 1973): Gill ATPase activity related to parr-smolt transformationand migration tn steelhead trout (Salmo gairdnert): influence 0f photoperiod and tempe-rature. COmp. Biochem. Physio1., 45B, 955-965.

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Seasonal Changes in Seawater Adaptability of the Hatcery Reared Juvenile Salmon, Oncorhycunsus Nerka

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