UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Factors affecting precocious sexual development in male rainbow trout Houston, Christopher James Gordon 1981

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1981_A6_7 H69.pdf [ 2.51MB ]
Metadata
JSON: 831-1.0095442.json
JSON-LD: 831-1.0095442-ld.json
RDF/XML (Pretty): 831-1.0095442-rdf.xml
RDF/JSON: 831-1.0095442-rdf.json
Turtle: 831-1.0095442-turtle.txt
N-Triples: 831-1.0095442-rdf-ntriples.txt
Original Record: 831-1.0095442-source.json
Full Text
831-1.0095442-fulltext.txt
Citation
831-1.0095442.ris

Full Text

FACTORS AFFECTING PRECOCIOUS SEXUAL DEVELOPMENT IN MALE RAINBOW TROUT by CHRISTOPHER JAMES GORDON HOUSTON B.Sc,  U.B.C.  1975  A THESIS SUBMITTED I N PARTIAL FULFILLMENT OF ' THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Department of Zoology) We a c c e p t t h i s t h e s i s a s c o n f o r m i n g t o t h e required standard  THE UNIVERSITY OF B R I T I S H COLUMBIA O c t o b e r 1981 c  C h r i s t o p h e r James G o r d o n H o u s t o n , 1981  In p r e s e n t i n g  this  thesis i n partial  f u l f i l m e n t of the  r e q u i r e m e n t s f o r an a d v a n c e d d e g r e e a t t h e of B r i t i s h Columbia, I agree that it  freely  the L i b r a r y  a v a i l a b l e f o r r e f e r e n c e and s t u d y .  agree that p e r m i s s i o n f o r extensive for  University  s c h o l a r l y p u r p o s e s may  for  financial  shall  of  The U n i v e r s i t y o f B r i t i s h 2075 W e s b r o o k P l a c e V a n c o u v e r , Canada V6T 1W5  DE-6  (2/79)  thesis  Columbia  my  It is thesis  n o t be a l l o w e d w i t h o u t my  permission.  Department  further  be g r a n t e d by t h e h e a d o f  copying or p u b l i c a t i o n of t h i s  gain  I  make  copying of t h i s  d e p a r t m e n t o r by h i s o r h e r r e p r e s e n t a t i v e s . understood that  shall  written  i i  ABSTRACT Rainbow  trout  (Salmo  n a t i v e t o B r i t i s h Columbia, were  reared  growth the  and a  varying  r a t e a n d body s i z e ,  from  two  non-native  conditions  useful  t o body w e i g h t  before  and  (Gonadosomatic  photoperiod  on  The r a t i o o f to  f o r s e p a r a t i n g mature and immature male f i s h and f o r  Premier  development.  lake f i s h t e s t i s  development  t h e expected date of spawning.  weight  the f i s h  strain  i n d e x ) was f o u n d  of  between t e n and twenty  s m a l l e r than t h i s  "critical"  (i.e.  no t e s t i s d e v e l o p m m e n t ) .  must  be  r e a c h e d by a c e r t a i n  one  that  p r e p a r a t i o n f o r spawning  the following  p h o t o p e r i o d regime  a  g r a m s , w h e r e a s most o f  size  remained  time of the year.  fish achieving  year  reached  immature  Apparently, this c r i t i c a l  'window' e x i s t s w h e r e i n  Altering  began  A t t h i s t i m e , s i g n s of  m a t u r a t i o n were e v i d e n t p r i m a r i l y among m a l e s body  stocks  t o examine e f f e c t s of  genetic stock,  determining the onset of gonadal In  wild  domestic  i n c i d e n c e and t i m i n g of t e s t i s development.  gonad w e i g h t be  under  gairdneri)  a  certain  size  Thus, a time size  begin  year.  d u r i n g t h e t i m e window h a d no  e f f e c t on t h e i n c i d e n c e o f s e x u a l p r e c o c i o u s n e s s , b u t d i d d e l a y spermatogenesis  by an u n d e t e r m i n e d  length of time.  iii  TABLE OF CONTENTS  ABSTRACT L I S T OF TABLES L I S T OF FIGURES ACKNOWLEDGEMENTS  i i iv v v i  INTRODUCTION  1  METHODS  8  I N I T I A T I O N OF T E S T I S DEVELOPMENT  8  EFFECTS OF GROWTH RATE AND DIFFERENT STOCKS  9  EFFECTS OF PHOTOPERIOD ON GONADAL DEVELOPMENT RESULTS  12 15  I N I T I A T I O N OF T E S T I S DEVELOPMENT  15  EFFECTS OF GROWTH RATES AND DIFFERENT STOCKS  25  EFFECTS OF PHOTOPERIOD ON GONADAL DEVELOPMENT  30  DISCUSSION  34  LITERATURE CITED  41  L I S T OF  Table  I . Arrangement of treatment  male rainbow t r o u t Table  TABLES  I I . Daily  Weight) ^ 1  3  groups  and  numbers  of  reared at various photoperiods  growth  slopes  v s Time f o r t h r e e  calculated  stocks  of  for  rainbow  14 (Body trout  held at d i f f e r e n t ration l e v e l s Table  I I I . P r o p o r t i o n s of p r e c o c i o u s  s t o c k s of rainbow t r o u t Table  IV.  slopes Table  26  Proportions  of  males found i n t h r e e  reared at three precocious  rations  males  and  28 growth  f o r rainbow t r o u t at three r a t i o n l e v e l s  V. C o m p a r i s o n o f mean w e i g h t s  male t r o u t  28  of mature and immature 30  V  L I S T OF  Figure  1.  Frequency  FIGURES  o f GSI v a l u e s i n r a i n b o w  s a m p l i n g p e r i o d J u l y 26, 1976 t o F e b r u a r y Figure  2. C h a n g e s i n mean GSI  rainbow 23, Figure  trout  values  for  trout  over  2 3 , 1977. maturing  16 male  d u r i n g p e r i o d J u l y 26, 1970 t o F e b r u a r y  1977  18  3. Mean t e s t e s w e i g h t  plotted against Figure  4.  (+1SE) o f m a l e r a i n b o w  trout  time  Relative  19  changes  i n gonad and s o m a t i c  growth  r a t e s l o p e s over time Figure  5. F r e q u e n c y  start rainbow  up  dates  trout  20  distributions and  body  of  sizes  back in  calculated maturing  male 23  vi  ACKNOWLEDGEMENTS I would l i k e and  particularly  Rempel  t o thank t h e s t a f f Messrs.  for their  of the Abbotsford  Bob L a n d , L a r r y M i t c h e l l  hatchery  and  Morley  considerable t e c h n i c a l assistance i n the f i s h  c u l t u r e , and a l s o S u z i n Crosby f o r h e l p w i t h t h e h i s t o l o g y . I would a l s o l i k e and for  moral support her  typing  review;  at the beginning and  considerable help  t o t h a n k Hugh S p a r r o w f o r b o t h  drafting  of the p r o j e c t ; Bing  skills;  i n machine p r o d u c t i o n  my s u p e r v i s o r Don M c P h a i l  Eric  the d a t a . Ministry  prodding  and  Parkinson  of t h e t h e s i s  Sanson forh i s and i t s  f o r h i s p a t i e n t support  a l o n g f i v e y e a r s ; a n d most p a r t i c u l a r l y , consistent  practical  A r t Tautz  over  f o rh i s  considerable assistance i n analyzing  The F i s h a n d W i l d l i f e of Environment provided  Branch of the B r i t i s h Columbia financial  support  for  this  project. Finally,  I  thank  encouragements, p r a c t i c a l work a n d much a p p r e c i a t e d  my  wife,  assistance  Jeannie, with  companionship.  for  tedious  constant  technical  1  INTRODUCTION The  f a m i l y Salmonidae  considerable  economic  remain  many  of  the  unexplored,  is  even  an  on  in  to  growth  (Campbell, which fish  fungal  (Nomura,  biology  areas  i t  has  the  cycle  important  undesirable  t h e r e i s an i n c r e a s e d invasions lies,  (Simpson, 1974),  lakes  reproductive  or  1976),  increased  might  side  reduced mortality  in flesh  quality  commercial  reproduction i s  commercial  cycle  life  susceptibility  l e s s d e s i r a b l e t o a n g l e r s and  u n n e c e s s a r y , as i n s t o c k e d over  life  have  f a r m e r s . T h e r e f o r e , i n c a s e s where n a t u r a l  control  of  management.  their  which  manager  1963;  the f i s h  and  controlling  1 9 7 1 ) , and a g e n e r a l d e t e r i o r a t i o n  makes  are  i n t e g r a l p a r t of the t r o u t ' s normal  D u r i n g spawning,  b a c t e r i a l and  salmon)  significance.  c y c l e , y e t f o r the f i s h e r y effects.  their  factors  c o m m e r c i a l a n d management Spawning  and  i m p o r t a n c e i n N o r t h A m e r i c a and t h e r e i s  a l a r g e body o f l i t e r a t u r e However,  (trout, char,  fish  allow  farms, f o r more  e f f e c t i v e management and h i g h e r r e t u r n s . The  reproductive cycles  interaction  of  hypothalamus, stimulating  various the  the  in fishes  factors.  pituitary  gland  development  1973).  development  also  However,  photoperiod  and t e m p e r a t u r e  de V l a m i n g ,  1972; de V l a m i n g ,  appears  Under  controlled the  Atz,  by  control  releases  (increase  gonads ( f o r r e v i e w s see P i c k f o r d and Donaldson,  is  the  of the  gonadotropins  i n gonad s i z e ) of t h e 1957;  Dodd,  1972;  t h e i n t e r n a l mechanism of g o n a d a l to  be  influenced  by  changes  ( f o r r e v i e w s see H a r r i n g t o n , 1974). Depending  on t h e  in 1959;  species,  2  either  of  these  c o n t r o l m e c h a n i s m s may be d o m i n a n t . I n b i r d s  and mammals t h e e n v i r o n m e n t reproduction fishes  remains  the  i s known t o a c t a s  primarily  environment  under  apparently  i n f l u e n c e on t h e r e p r o d u c t i v e c y c l e Experiments  manipulated.  For  environmental  stimuli  birds  does  not  endocrine  exerts (Dodd,  a  and  1971).  fish  c o n t r o l . In  more  powerful  1972).  i t has  with  an  However,  f o r the maintenance necessarily  but  demonstrated  of r e p r o d u c t i v e processes can  interact  (Schwassman,  responsible  trigger  w i t h p l a n t s , b i r d s and f i s h have  t h a t t h e t i m i n g and f r e q u e n c y  rhythm  a  of  explain  a  the  been  shown  internal  an  that  biological  endogenous  reproductive initiation  be  rhythm  behaviour  of  gonadal  d e v e l o p m e n t p e r s e , w h i c h must o c c u r a t some t i m e p r i o r  to the  onset of r e p r o d u c t i v e behavior. , In  mammals  variation and  rats),  there  to  be a r e s p o n s e  (Donovan  and  occurs  Swerdloff  (1) r e l e a s e  van  of  der  Werfften  sensitivity  in p i t u i t a r y For (increase  of  Bosch,  i n f a s t e r growing  suggest  an  initiation  puberty  is  t o maturation of the b r a i n - p i t u i t a r y  sooner  (1972)  The  three  inhibitory  to pituitary  1965),  which  individuals.  Odel  possible  mechanism  s t i m u l a t i o n o f t h e g o n a d by t h e p i t u i t a r y . gonadal  i s considerable  i n t h e time o f p u b e r t y , even under c o n t r o l l e d g e n e t i c  apparently and  and  environmental conditions.  thought axis  (humans  explanations; which  ( 2 ) an  prevents  increase  in  p r o d u c t s , o r (3) an i n c r e a s e  secretions.  f i s h the p i t u i t a r y in size),  i s r e q u i r e d f o r gonadal  but i t i s not c e r t a i n whether  development gonadotropin  3  is  necessary  spermatocytes  for  from  maturation  spermatogonia;  purposes,  i t is  essential  for initiation  probably gonadal  sufficient  separate  sexual  1969).  t o conclude  of  processes  authors  gonadal  primary  For  present  that the p i t u i t a r y i s development  control  gonadal  and  Dixon,  have  successfully  (Funk a n d D o n a l d s o n ,  1969; H i r o s e a n d D o n a l d s o n , difficult  gonadal  to  development  delay in  1972), but t h i s t e c h n i q u e fish  cultural  successful large  development and  induced  precocious  1972),  spawning. chinook  salmon  and  but i t i s a p p a r e n t l y retarded  (Bonham a n d  not  Similarly  i n p r e v e n t i n g spawning,  Marushige  X-irradiation  i s probably  programs.  1972;  useful  Donaldson, i n routine  hypophysectomy,  w o u l d be  though  impractical  on  a  scale, No  single  factor  has  d e t e r m i n i n g age a t f i r s t fish  size  could  been  identified  as  critical in  spawning i n s a l m o n i d s . Rate exert  an  influence  of  genetic  effects.  There  are  possibly  some s t o c k s m a t u r e a t l a t e r a g e s , se,  i . e . males  often  some  documented  stock differences  a s w e l l a s an e f f e c t  reach  growth  through  p h y s i o l o g i c a l maturation process but there a r e a l s o  per  that  development i n salmon and t r o u t w i t h p u r i f i e d e x t r a c t e d  salmon g o n a d o t r o p i n  or  Hoar,  of  maturation.  Numerous  more  (production  maturity  one  where  of  year  sex  before  females. In suggest  non-anadromous s a l m o n i d s , t h e r e that  fish  size  although i t i s d i f f i c u l t  influences  is age  some at  evidence  first  t o separate e f f e c t of s i z e  to  spawning,  from  growth  4  r a t e and g e n e t i c f a c t o r s . Lake were  found  growth  to  t r o u t which  although  within  tended  to  a  trout  size,  rapid  stock  than those which  slower  growing,  grew  smaller  m a t u r e a t a l a t e r age ( C a m p b e l l , 1971;  McFadden, 1965). A s i m i l a r , growth,  early  1 9 6 7 ) . However, brown t r o u t s t o c k s  w h i c h grew q u i c k l y d i d n o t m a t u r e e a r l i e r  individuals  matured  be l a r g e f o r t h e i r age a n d h a d e x h i b i t e d  (Hanson a n d W i c k w i r e ,  slowly,  had  relationship  between  rapid  early  a n d e a r l y m a t u r a t i o n h a s been shown f o r r a i n b o w  ( A i m , 1959; K a t o ,  1975; O o t a  e t a l . , 1965).  Among anadromous s a l m o n i d s t h e i n f l u e n c e o f s i z e on age o f first  maturation i s similar  species.  M a l e c h i n o o k salmon  growing as j u v e n i l e s that  sockeye  originated salmon  t o t h a t found  salmon  (Flain,  with  mature e a r l i e r  from  the  sea  f r o m l a r g e eggs ( w h i c h p r o d u c e d  accelerated  i f they a r e f a s t e r  1970), and B i l t o n  returned  non-anadromous  (1971)  suggested  earlier  i f  large fry).  For pink  i n heated sea-water, the s m a l l p r o p o r t i o n of  m a l e s w h i c h became s e x u a l l y m a t u r e w i t h i n t h e i r  first  somewhat  larger  (MacKinnon  Donaldson,  1976). Oota  identify  than  their et a l .  contemporaries (1965)  a maximum l e n g t h b e y o n d w h i c h  variability  in  factors  f e e d i n g b e h a v i o u r s , growth  size  as  at  MacKinnon salmon  this  emergence and  characteristic  and  Donaldson  reach a c r i t i c a l  t h e n m a i n t a i n e d under In  they  genetic  found  y e a r were  i t difficult  and to  f i s h always matured but is  expected  when  such  r a t e , time of h a t c h i n g ,  variation  are  considered.  (1976) p o s t u l a t e d t h a t when m a l e p i n k  s i z e gonad development  starts  and  is  environmental control.  e x a m i n i n g t h e g e n e t i c component o f m a t u r a t i o n , N a e v d a l  5  e t a_l. (1978) r e p o r t e d age  at  first  that for A t l a n t i c  spawning  was  primarily  f a c t o r s . More g e n e r a l l y , i n t e r s p e c i f i c exist  such as the v a r i a t i o n  with similar {4  years}  maturing  early l i f e salmon)  select  could  be  influenced  f o r a y o u n g e r age a t situation  is  Schaeffer  and  spawning  increases  Elson  first  postulated (1975)  ages  and  genetic  by  between  species  {2 y e a r s } and chum  5 - y e a r o l d ) and e a r l y  of  rainbow life  trout.  history  with  fishery  i s also likely fish.  Thus,  heritable  component  selective  forces  reproduction,  These  tactics.  that  the d i f f i c u l t y salmon.  The  to select against  there  are  several  o f age a t f i r s t operating  on  whereas  to the  for a declining population.  found  t h e anadromous A t l a n t i c  older  (4-  of  in  (1976) s u g g e s t s t h a t a g r o w i n g p o p u l a t i o n w o u l d t e n d  reverse  for  the r e s u l t  (e.g. pink  ( 2 - and 3 - y e a r o l d ) s t o c k s  differences Stearns  late  variation  d i f f e r e n c e s a r e known t o  i n spawning  histories  and  salmon,  mean  age  at  of upstream impact  first  migration  of  a  heavy  l a r g e r and  presumably  means  which  by  the  spawning might respond t o different  species  and  populations. Besides  endocrine,  genetic  and  growth  mechanisms,  e n v i r o n m e n t a l v a r i a b l e s a r e known t o i n f l u e n c e t h e  reproductive  c y c l e . However, v a r i a b l e s such as p h o t o p e r i o d have been c o n s i d e r e d spawning  rather  only  than  and  i n t e r m s o f t h e i r e f f e c t on t i m i n g o f  their  i n f l u e n c e upon t h e i n i t i a t i o n  gonadal development  a n d t h e r e f o r e age a t f i r s t  and  c o n c l u d e d t h a t t e m p e r a t u r e was  Orton  controlling  (1940)  temperature  gonad d e v e l o p m e n t  in Atlantic  spawning.  salmon,  Jones  important and  of  in  Titarev  6  (1974)  maintained  trout  that  development.  temperature development  is  temperature  However, not  (de  it  is  Vlaming,  1972).  in  r a t i o n , any  i n rainbow held  that  controlling  Since  on m a t u r a t i o n i s p r o b a b l y m e d i a t e d  growth  is  i n f l u e n c e of  sexual directly  temperature  t h r o u g h i t s e f f e c t on  growth  ( B r e t t e t a l . , 1969). Photoperiod,  however,  influences  more d i r e c t l y . H a z a r d and Eddy ( 1 9 5 0 ) photoperiod  hastened  summer. C o r s o n ( 1 9 5 1 ) was day  critical  generally  significant  r e l a t e d t o t e m p e r a t u r e and  rate  was  fish  to  a  constant  stimulation remained  found  similar  17  in  results,  h o u r s of l i g h t  by  green  changing  day  period  of  length  spawning  has  found t h a t a s i m i l a r c o n d i t i o n  However, f o r the purposes establish  whether  of t h i s  specific  to  acting  as  a  t o midAllison  as  7 hours  on  l o n g as  of  immature  not  stimulation  gonadal require  temperature  is  necessary  been c o m p l e t e d .  Henderson  seemed t o e x i s t  in trout.  study  it  was  photoperiod  trigger  and  found t h a t did  e s s e n t i a l a t t h e t i m e when gonad d e v e l o p m e n t opposed  and  photoperiod  sunfish  h i g h . However, p h o t o p e r i o d  one  accelerating  by s i x weeks by e x t e n d i n g t h e  i n f l u e n c e of  immature  that  spawning  p e r i o d from a f a l l  r e v i e w e d by Schwassman ( 1 9 7 1 ) , who  maturation  (1963)  obtained  ( 1 7 L , 7 D ) . The  is  once  (1955)  spawning  a b l e t o d e l a y spawning  length  darkness  the  the t i m i n g of  for  necessary  conditions was  to were  initiated,  the onset of  as  spawning  behavior. I n summary, t h i s variety  of i n t e r a c t i n g  r e v i e w of t h e l i t e r a t u r e factors are responsible  indicates that for  a  initiation  7  of  gonad  d e v e l o p m e n t and p o s e s a s e r i e s  be e x a m i n e d e x p e r i m e n t a l l y . F i r s t l y , and  at  what  development Secondly, size  size  by can  i t  is different  whether  and  evaluate  into  or  factors  the  initiate  gonadal  whether t h e average  s t o c k s ? I f t h i s were  maturity. Lastly, the  trout  the controversy  environmental  o v e r age a t f i r s t  i  energy  for different explain  a t what t i m e o f  rainbow  be e s t a b l i s h e d  i n d e p e n d e n t l y of e x t e r n a l on age a t f i r s t  male  redirecting  s u c h v a r i a t i o n may to  do  of q u e s t i o n s t h a t  can year gonad  biomass? critical the  case  i n the l i t e r a t u r e  genetic  effects  as  acting  are the predominant  influence  is i t  identify  possible  to  r o l e of p h o t o p e r i o d i n terms of i t s c o n t r o l spawning?  8  METHODS  I N I T I A T I O N OF T E S T I S DEVELOPMENT In t h i s experiment trout  was  examined  development. was 4500  to  yearling  Abbotsford  i n r e l a t i o n t o the annual  A second  related  t e s t i s development of maturing  rainbow  of i n d i v i d u a l  trout  (10—12g)  hatchery i n early July  f i b r e g l a s s tanks  (capacity  190 ) .  at  the  Kootenay  Trout  i f body  fish.  size  Approximately  were  received  at  1976 a n d p l a c e d i n 1.2m  oval  The  fish  Premier Lake i n e a s t e r n B r i t i s h Columbia staff  t i m i n g o f gonad  o b j e c t i v e was t o d e t e r m i n e  maturation  rainbow  originated  from  a n d h a d been r e a r e d by  Hatchery  near  Cranbrook  for  a p p r o x i m a t e l y one y e a r . The e x p e r i m e n t a l t a n k s h a d a f l o w o f 20 1/min  from a nearby  s p r i n g a t a constant temperature  F i s h were f e d s e v e r a l t i m e s e a c h day food.  Beginning  on  weeks u n t i l  February  sacrificed,  towel  removed.  Ovaries  characteristic attachment. enlarged  area  of  26,  in  sample  weighed,  immature  the  low  commercial  of  thirty  measured,  fish  enlargements under  a  fish  1976, a n d c o n t i n u i n g e v e r y two  23, 1977, a dried,  oval  Viewed  July  with  o f 9.5° C.  were  at  anterior  magnification,  was  and t h e gonads  distinguished  the  o v a r y was c l e a r l y  fish  by  point of  this  slightly  g r a n u l a r as compared  w i t h t h e smooth t e x t u r e o f t h e t e s t i s . After formalin  testes and l a t e r  were  removed,  weighed  were  stored  i n 10%  i n d i v i d u a l l y w e i g h e d t o t h e n e a r e s t O.OOlg.  No c o r r e c t i o n was made f o r w e i g h t were  they  only a f t e r  loss  i n formalin  t h e y h a d been s t o r e d  but  testes  f o r a t l e a s t two  9  w e e k s . I t was loss  assumed t h a t a f t e r  occurred.  The  gonadosomatic  t h e p e r c e n t a g e of t h e t o t a l material.  two weeks  no  further  i n d e x ( G S I ) i s a measure o f  body w e i g h t a t t r i b u t a b l e  As t h e t e s t e s m a t u r e  to  t h e y grow more r a p i d l y  r e s t o f t h e body a n d h e n c e t h e r a t i o o f body w e i g h t weight  changes.  calculated of  The  i n two  GSI  of a s e l e c t e d  t h e GSI  ratio  gonad x 2/body w e i g h t x 100 Robertson  difference  i n w e i g h t b e t w e e n t h e two  of  calculation  testes/body weight) x identify  mature  and  was  found  100.  The  growth  rainbow  there  was  t e s t e s and an  rate,  trout  latter  method  was  from  also  ration  designed and  genetic  development. two  wild  to  an e l e v a t i o n o f 914m, source  of  wild  H a t c h e r y . The  used  to  examine stock  During  h a s a TDS  other wild  of  rainbow s t o c k was  I79ppm  trout  and  on  July  domestic  wild stock  serves  Lake  30'  lake i s at  f o r the Kootenay  from Pennask  the  56'/H5°  r e g i o n o f B r i t i s h C o l u m b i a . The  stock  of  the  early  s t o c k s a n d one  f r o m P r e m i e r L a k e , a 229ha l a k e l o c a t e d a t 49°  i n the East Kootenay  l0%-20%  alternative  s t r a i n were r e c e i v e d a t t h e A b b o t s f o r d h a t c h e r y . One was  1972).  DIFFERENT STOCKS  i n c i d e n c e of p r e c o c i o u s male 1976,  that  Donaldson,  one  with time.  a b o v e e x p e r i m e n t was of  are  i m m a t u r e f i s h and e s t a b l i s h t h e p a t t e r n  EFFECTS OF GROWTH RATE AND  effects  &  be  recommended: ( t o t a l w e i g h t o f b o t h  t e s t i s and body w e i g h t c h a n g e s  The  f i s h can  t h a t b o t h gonads  Funk  However,  method  testis  i s d e t e r m i n e d as weight of  (as i n  (1958)  gonad  than the  to  individual  s e p a r a t e ways. A s s u m i n g  t h e same s i z e ,  weight  as  a  Trout  which  is  10  located TDS  a t 50°  00'/l20° 08'  o f 27.0ppm a n d  the p r o v i n c i a l Fish  a t an e l e v a t i o n  of  1418m. I t h a s  i s 961ha. Pennask i s a s o u r c e  of  eggs  for  h a t c h e r y a t Summerland.  from  b o t h Pennask and  Premier  l a k e s n o r m a l l y mature  a s t h r e e - y e a r - o l d s , b u t many m a l e s a r e a y e a r y o u n g e r a t spawning.  The  the t r i b u t a r y lake  in  several  the  spawning streams  fish  just  spring.  generations  characterized  by  The at  in  weight  fish of  from  oval  fibreglass  Each  the J u l y  8,  The incidence  tanks  growth  1976  day.  from each  (capacity  to February  i n the f a l l  levels,  Every  23,  Premier fish in  and  consisted  fish  f o r each  in  year. 10-12g  1.2m  r e c e i v e d from  o f 9.5°  C  year  throughout  period. examining  the  three s t o c k s fed at  ration/stock t a n k was  were t h e n hand f e d  treatment  calculated several  fish  was  a n e s t h e s i z e d , t o w e l d r i e d , wet  t h e y were t h e n  Pennask  eighteen  of  weeks a s a m p l e o f t w e n t y  tank, l i g h t l y  is  normally  and  of f l o w  rearing  each  ration  The  1977  the  were s i x m o n t h s  ) . W a t e r was  development with  The  two  190  in  been r e a r e d f o r  of t h e  at a temperature  design  precocious  once.  measured;  leaves  domestics  s u p p l i e d w i t h 20 /min  experimental of  appear  hatchery  r a t e s . The  older  s u p p l i e d water  measured out d a i l y .  and  Abbotsford  r e a r e d i n l o t s o f 250  t a n k was  ration  replicated  has  when r e c e i v e d i n e a r l y J u l y . The  a s p r i n g which  each  strain  ice  first  t h e t h r e e s t r a i n s were a l l a p p r o x i m a t e l y  E a c h g r o u p was  round.  20-40cm and the  were o n e - y e a r - o l d s w h i l e t h e d o m e s t i c  age.  three  from  after  domestic  the  rapid  range  shortly  spawn a s t h r e e - y e a r - o l d s and Fish  a  and  times removed weighed  r e t u r n e d t o t h e t a n k . From  their  11  mean w e i g h t a n d of  4%,  2%,  procedure sampled and  and  t h e number o f f i s h  i n the tank the d a i l y  1% body w e i g h t / d a y  was  the  same  as  was  for  c a l c u l a t e d . The  the  f i s h were s e x e d a n d c l a s s i f i e d  the t o t a l  February  1977  first  ration  sampling  experiments.  as mature  and  immature  number o f m a t u r i n g m a l e f i s h were r e c o r d e d when t h e  experiment  weights are given throughout  was  t h i s paper  terminated. w i t h one  The  A l l  standard  until mean error  i n b r a c k e t s (±1SE). Because of t h e i r the  above  s i z e and  experiments  that  combined i n t o n i n e groups for  space  remained  sacrificed  All  1977,  were moved t o  previously  described  p h o t o p e r i o d was  from  On May  1,  the  high  a  of  after  s a l m o n i c i d a , the c a u s a t i v e agent groups  new  procedures  the  and  m e a s u r e d . The and  Pennask  holding were  r a t i o n Premier group,  August  stock  o f f u r u n c u l o s i s . The  a l o s s o f 70 f i s h  domestic  facility  continued.  kept  were  remaining where A  the  natural  lights.  ( c . 4 0 % ) was  experienced  b u t no o t h e r  significant  On  August  f i s h were k i l l e d and  2 6 t h p e r i o d was  were  t h e d i s c o v e r y o f Aeromonas  l o s s e s o c c u r r e d d u r i n g the experiment. Premier  from  the m a t u r a t i o n r a t e s of  simulated with fluorescent 1977,  1977  (no r e p l i c a t e s ) . E a c h g r o u p was  fish.  on M a r c h 2 1 ,  the f i s h  on F e b r u a r y 23,  a v a r y i n g p e r i o d of time t o v e r i f y  the v a r i o u s treatment  six  limitations,  chosen  26,  1977,  l e n g t h s and so t h a t  s p r i n g s p a w n e r s c o u l d be e x a m i n e d t o g e t h e r .  a l l  weights  both  fall  12  EFFECTS OF PHOTOPERIOD ON GONADAL DEVELOPMENT The  third  of p h o t o p e r i o d  e x p e r i m e n t was d e s i g n e d  on t h e i n i t i a t i o n o f g o n a d a l d e v e l o p m e n t , w i t h a  view t o u s i n g photoperiod means  of  eliminating  development  t o examine t h e e f f e c t s  was  c o n t r o l i n p r o d u c t i o n h a t c h e r i e s as a  the  "window"  initiated.  The  during  which  sexual  o b j e c t i v e s of the experiment  were; 1. To a s c e r t a i n w h e t h e r o r n o t a d i f f e r e n c e i n t h e p a t t e r n o f d e v e l o p m e n t was o b s e r v e d lighting  which  (outdoor)  simulated  been k e p t  in  latter  the hatchery  on  the  Premier  the  disease  photoperiods.  at Abbotsford. artificial  and a f t e r a p e r i o d of and  to  groups  regime  for  periods  (June) c o u l d a f f e c t t h e  15, 1977, 1800 u n d e r y e a r l i n g r a i n b o w t r o u t  natural,  from t h e Kootenay  The f i s h  were  natural,  and  offsite  divided short  holding  to  a l l o w p r e p a r a t i o n of the treatment  were  kept  April on  1, a  holding p e r i o d , but the a r t i f i c i a l until April  had  development.  e x p e r i m e n t was s t a r t e d on length  7 l i g h t : 1 7 dark  L a k e s t o c k were s h i p p e d  the f a c i l i t y  light),  and n a t u r a l  development r a t e s f o r f i s h which  normal p l a n t i n g p e r i o d  On F e b r u a r y  groups;  natural photoperiod,  e x p e r i m e n t was t o i n d i c a t e i f h o l d i n g y e a r l i n g f i s h  i n c i d e n c e of p r e c o c i o u s  to  (fluorescent)  on v a r y i n g d u r a t i o n s o f 7 l i g h t : 1 7 d a r k  bracketing  the  a  artificial  photoperiods.  2. To e x a m i n e t e s t i s  The  between  1.) The a b o v e g r o u p s  1977.  7:17  (Note:  photoperiod  of  hatchery into  3  (seven-hour check  for  areas, the Short  day  during the  g r o u p was on a n a t u r a l c y c l e were  further  subdivided  as  13  outlined  in Table I.  Table I  Arrangement of t r e a t m e n t g r o u p s and numbers o f male rainbow t r o u t r e a r e d at v a r i o u s p h o t o p e r i o d s .  Group  Sub-Group  Mark  Natural  Replicate 1 Replicate 2  Untagged Untagged  Outdoors Outdoors  200 200  Artificial  Replicate 1 Replicate 2  Untagged Untagged  Fluorescent Fluorescent  200 200  Tagged Tagged Tagged Tagged Tagged  7:17 c o n s t a n t Outdoors/May Outdoors/June Outdoors/July Outdoors/Aug  -  Short  — — —  Treatment  Numb<  400 150 200 1 50 1 00  4 1 4 2  1800  Due  to  a  shortage  of  n e c e s s a r y t o mark i n d i v i d u a l groups  and  combine  outdoor fish  rearing  from  the  r e c o v e r y a t t h e end o f t h e e x p e r i m e n t .  was  desirable  individual  fish  that  could  be  Individual  where s i z e s  of  fish  at  various  f r o m t h e mean g r o w t h  f i s h were t a g g e d i n e a r l y May  tags attached to the d o r s a l  pond  marking r a t e of  then r e l a t e d t o t h e i r  T h i s p r o v i d e d a check  All  treatment  i t w o u l d p r o v i d e d a t a on t h e g r o w t h  development.  calculated  short  i t was  them i n a s i n g l e 2m o u t d o o r c i r c u l a r  for  since  space,  sexual  f o r the p r e v i o u s experiments critical  rate with  times  were  f o r each t r e a t m e n t small  Floy  back group.  fingerling  s u r f a c e of the f i s h a n t e r i o r  to the  14  dorsal f i n . All  f i s h were grown u n t i l  S e p t e m b e r 6, 1977 a t w h i c h  point  t h e f i s h were s a c r i f i c e d , wet w e i g h e d a n d m e a s u r e d . T e s t e s were removed  from  minimum  of  examination  the three  m a l e s and f i x e d  i n Bouins f i x a t i v e . A f t e r  weeks,  selected  testes  for  histological  were embedded i n p a r a p l a s t . The c o o l e d b l o c k s were  s e c t i o n e d a t a t h i c k n e s s o f 7 m i c r o n s and s e v e r a l sections  mounted  on  a single  stage of development as  full  intact  s l i d e . Once d r y , t h e t i s s u e  s t a i n e d w i t h h a e m o t o x y l i n a n d e o s i n and t h e for  a  slides  was  classified  follows:  Stage  1 - only spermatogonia  present  Stage  2 - s p e r m a t o g o n i a , p r i m a r y and  secondary  spermatocytes Stage  3 - spermatogonia,  s p e r m a t o c y t e s and some  spermat i d s Stage  4 - spermatogonia,  s p e r m a t i d s a n d many  free  sperm i n t h e lumen o f t h e d u c t s Stage Those immature, considered fully,  5 - o n l y s p e r m a t i d s a n d f r e e sperm p r e s e n t fish  classified  whereas to  be  any  as  fish  mature  or  "stage  at  stages  maturing.  one" two Stage  were c o n s i d e r e d to  five  five  f u n c t i o n a l l y mature males w i t h f r e e f l o w i n g  fish  sperm.  were were  15  RESULTS  I N I T I A T I O N OF T E S T I S DEVELOPMENT This  experiment  dealt  a d d r e s s e d t h r e e p r o b l e m s . The time was  of year t h a t t e s t i s  only  with  first  p r o b l e m was  calculate  was  stock  and  to identify  the  d e v e l o p m e n t b e g a n . The s e c o n d p r o b l e m  t o d e t e r m i n e t h e l e n g t h of t h e  development  Premier  initiated,  the s i z e of the  time  and  fish  the at  period final  the  during  problem  time  they  which was  to  began  to  mature.  P r e v a i l i n g e n v i r o n m e n t a l c o n d i t i o n s were a l s o n o t e d i n  relation  t o the t i m i n g of the gonadal development.  To d i s t i n g u i s h b e t w e e n m a t u r e and frequency the GSI  plot  of the t o t a l  immature  a  GSI  sample of male f i s h measured  over  e x p e r i m e n t was made. A b o u t a t h i r d value  of  b e t w e e n 0.5 a n d 2.5 a  of the f i s h  (Fig.  examined  had  may  f i s h was c o n s i d e r e d  have a l s o  a  GSI  1). For the purpose of t h i s  a v e r a g e f o r t h e m a t u r e g r o u p s was with  fish  n a t u r e of the c u t - o f f number  of  fish  less  fish  to that which  i m m a t u r e f i s h among t h e m a t u r e . The a v e r a g e  f o r t h e i m m a t u r e g r o u p was 0.11  was  of  males,  i n c l u d e d w i t h t h a t g r o u p a few m a t u r i n g  would have i n c l u d e d  concern  a  analysis,  a l l immature  w i t h G S I ' s o f 0.25-0.50. T h i s e r r o r was p r e f e r r e d  GSI v a l u e  value  i m m a t u r e i f i t s GSI was  t h a n 0.5. T h i s method c o r r e c t l y c l a s s i f i e d but  (34%) h a d  l e s s t h a n 0.5 a n d w h e r e a s 6 3 % h a d G S I ' s o f more  t h a n 2.5. O n l y 3% o f a l l f i s h  therefore,  fish,  (3%)  5.6  (±.007),  while  the  (± . 3 ) . S i n c e t h e p r i m a r y  known t o be m a t u r i n g , t h e c o n s e r v a t i v e  value in  (GSI = 0.5) c o m b i n e d w i t h t h e s m a l l the  questionable  range  gave  an  16  0.2  >O LLI  O UJ  rr  0.1  LL.  0.02  0.01  0.05  0.1  G S I  Fig.  1.  0.5  2.5  5.0  7.5  10.0  V A L U E S  Frequency of occurrence of gonadosomatic index (GSI) v a l u e s i n r a i n b o w t r o u t ( P r e m i e r s t o c k ) s a m p l e d o v e r t h e p e r i o d J u n e 26, 1976 t o F e b r u a r y 23, l'§7 7. GSI v a l u e s o f 0.25 t o 2.5 i n d i c a t e onset of m a t u r i t y .  17  acceptable  method  of  classification .  External  1  changes  morphology  ( i . e . c o l o r a t i o n , head shape changes, e t c . )  associated  w i t h m a l e s p a w n i n g s a l m o n i d s were  this  early  least  5.0 c o u l d m a t u r e a n d i m m a t u r e f i s h be  basis  of  stage.  Indeed,  abdominal  p r a c t i c e and w i t h Several  not u n t i l  shape  and  not  in  normally  apparent  at  t h e GSI h a d r i s e n t o a t  then  separated  only  after  development  over  on  the  considerable  some e r r o r . .  patterns  of  GSI  time  are  t h e o r e t i c a l l y p o s s i b l e , d e p e n d i n g on t h e r e l a t i v e g r o w t h o f t h e somatic  and gonadal components a t d i f f e r e n t t i m e s of t h e y e a r .  Immediately a f t e r sampling increasing  and  high  began  July  ( 4 . 0 - 8 . 0 ) GSI v a l u e s  A u g u s t 2 4 , 1976 t h e a v e r g e GSI (8.3)  on  had  23,  1976  rapidly  were o b s e r v e d a n d by  reached  a  maximum  value  ( F i g . 2 ) . A t t h i s p o i n t , h o w e v e r , an o b v i o u s d e c l i n e  observed which continued The either  GSI d e c l i n e by  the  body g a i n i n g gonad  weight  late  with  time  to gain  at a lesser rate  indicated  continued  Therefore, decline  the testes in  GSI  is  that  sometime  September.  in early  weight-testis  explained  testis.  A  plot  of  i n maturing f i s h the peak  in  GSI  ( F i g . 3 ) . Thus, t h e t e s t e s underwent a  which  growth r a t e d e c l i n e d  be  weight a f t e r the August  of r a p i d growth beginning unt'il  could  l o s i n g w e i g h t , o r a l t e r n a t i v e l y by t h e  period  (body  August  w e i g h t more r a p i d l y t h a n t h e  t e s t i s continued albeit  t o 5.0 a t t h e e n d o f t h e e x p e r i m e n t .  after  testes  was  increased  d i d not  lose  explained  by  to  July  26,  Furthermore, as t h e t e s t i s  September,  weight)  prior  the  somatic  noticeably  weight changes  but in  growth  (Fig. 4). rather  growth  the rate  10.0 LU CO  8.0  + 1  II CO  6.Oh  LU  2.0  i  'i  -z. < 4.0 1  JUL 26  AUG 24  SEP 22  OCT NOV 21 17  DEC 15  JAN 12  FEB 9  D A T E Fig.  2.  Changes i n mean (+1SK) g o n a d o s o m a t i c i n d e x ( G S I ) f o r m a t u r i n g male r a i n b o w t r o u t ( P r e m i e r s t o c k ) d u r i n g t h e t i m e p e r i o d J u l y 26, 1976 t o F e b r u a r y 2 3 , 1977.  co  UJ  JUL 26  AUG 24  SEP 22  OCT 21  NOV 17  DEC 15  JAN 12  D A T E Fig.  3.  Mean t e s t i s w e i g h t (+1SE) o f m a l e r a i n b o w t r o u t ( P r e m i e r s t o c k ) p l o t t e d against time. T e s t i s weight i n c r e a s e s over the e x p e r i m e n t a l p e r i o d .  I-H  MAY 29  Fig.  4.  ^  1  JUL 26  1  AUG 24  :  I  SEP 22 DATE  :  I  OCT 21  I  NOV 17  Transformed (weight- 1/3) d a t a f o r g o n a d a l and s o m a t i c w e i g h t s s h o w i n g changes i n gonad growth r a t e ( s l o p e s ) o v e r t i m e . Cionadosomatic Index v a l u e s are a l s o i n c l u d e d f o r untransformed d a t a .  L_  DEC 15  relative (GSI)  21  d i f f e r e n c e s b e t w e e n t e s t i c u l a r and s o m a t i c The growth in  above a n a l y s i s  identified a rapid  d u r i n g J u l y and August,  the f i r s t  To  of  i n weight perform  transformation  This  necessitated  t o t h e changes i n somatic  back  calculation,  f o r somatic  weight  (1948) and l a t e r  and  a  testis  Iwama a n d T a u t z  ( w e i g h t / ) produced  good l i n e a r  weight  t r o u t growth,  although a l o g transform or instantaneous  r a t e s c o u l d h a v e been a s e a s i l y u s e d . The p r o c e d u r e mean w e i g h t s  and  t h e w e i g h t s , and then back c a l c u l a t e  testes  size  results for  t h e n was t o  a t any time p r i o r  to July  26 t o A u g u s t the  body  o f t h e i m m a t u r e f i s h was 0.11 (±.007), t h i s v a l u e was  to  identify  begun t e s t i s  d a t e when any o f t h e m a t u r e f i s h  development.  Spec i f i c a l l y ,  where  W  t  T  t  l / 3  l / 3  =  W /  =  T  1  + b t  3  G  1 0  /  w  3  + b t t  24, size  26. S i n c e t h e mean  GSI  the  growth  f o r t h e somatic and gonadal components of  t h e GSI d u r i n g t h e r a p i d g r o w t h p e r i o d o f J u l y linearize  was  ( i n press)  that  3  weight.  linearizing  demonstrated  1  an  t h e t i m e a t w h i c h t h e t e s t e s began  relative the  required. Haskell  measure  gonadal  s a m p l i n g showed t h a t g o n a d a l d e v e l o p m e n t was w e l l  t o 'back c a l c u l a t e '  increasing  period  b u t t h e h i g h GSI v a l u e s r e c o r d e d  underway a t t h e s t a r t o f t h e e x p e r i m e n t . attempt  tissue.  used  sampled had  22  W W  t  =  Somatic  weight at time t  D  =  Somatic  weight at time  0  T  t  =  T e s t i s weight at time t  T  Q  =  T e s t i s weight  t  =  Number o f d a y s  b  =  S l o p e of t h e r e g r e s s i o n of w e i g h t time  at time  0  was  o b t a i n e d . A p p r o x i m a t e l y 30% o f t h e f i s h  in  the  week p e r i o d  vs  (days)  U s i n g t h e above a n a l y s i s , a d i s t r i b u t i o n  first  1/3  two weeks o f J u n e a n d  of s t a r t i n g  started  to  o v e r 70% s t a r t e d  f r o m mid-May t o t h e end o f J u n e  dates mature  i n the  6-  It  was  (Fig. .5).  o b s e r v e d , h o w e v e r , t h a t t h e c a l c u l a t e d v a l u e s were s e n s i t i v e the  back  c a l c u l a t i o n p r o c e d u r e . T h i s was  n a t u r e of the i n c r e a s e ( p a r t i c u l a r l y very  small  results,  fish  The  d a t e s of J u l y  an  analysis  of  variance  this,  was  produced performed  average  times  for  s t a r t i n g dates  1976;  August  10,  each  sampling  bias related  significant differences  starting  26,  the  growth  t h e back c a l c u l a t i o n p r o c e d u r e  s i n c e t h e mean w e i g h t s were d i f f e r e n t  average  similar.  if  ANOVA s h o u l d h a v e d e t e c t e d any  s a m p l e p e r i o d s . No the  and  s t a r t i n g d a t e s and w e i g h t s as a f u n c t i o n of  p e r i o d . The of  weight)  limits.  determine  examining  geometric  d e f i n e d the p e r i o d of a c c e l e r a t e d gonadal  within acceptable  precise  gonadal  to the  s i z e o f t h e g o n a d s a t s t a r t up t i m e . D e s p i t e  the procedure  To  due  to  f o r the  were  to  size  different  observed  and  s a m p l e d a t e were v e r y  (±1SE) f o r t h e t h r e e s a m p l e 1976  and  August  24,  1976  0.3  O  Zo.| UJ  a UJ  cc  o . i l  0  MAY 15  31  JUN 15  3 0  J U L 15  31  10  15  2 0  25  25  STARTING DATE  BODY WEIGHT (g)  Fig.  5.  +  F r e q u e n c y d i s t r i b u t i o n s o f b a c k c a l c u l a t e d s t a r t up d a t e s and body s i z e s i n m a t u r i n g m a l e r a i n b o w t r o u t ( P r e m i e r s t o c k ) ..  24  were  June  17  (± 3 d a y s ) ,  (±7 days),  June  16  (±6  days)  and  J u n e 17  respectively.  T h i s a n a l y s i s i n d i c a t e d t h a t t h e time p e r i o d a t which "decision" the date  t o spawn was made was a p p r o x i m a t e l y  of a c t u a l  calculated definite  spawning. F u r t h e r , the absence of  values  before  'window'.  This  May  back  1, i n d i c a t e d t h e p r e s e n c e  of a  window  was  further  of the proportion of maturing  sample.  was  reasoned  GSI  values  accelerated critical  size  controlled should  and  Examination  as  the fish  i n the p r o p o r t i o n of  lending  further  i n each  to  develop  f u n c t i o n of reaching a to  an  proportion passed  environmentally of  their  fish  maturing  critical  size.  support  fish  was  observed  with  t o the theory that a d e f i n i t e  time,  'window'  p r e s e n t d u r i n g t h e p e r i o d f r o m mid-May t o m i d - J u l y . With  the  determined,  presence  i t remained  the environmental same p r o c e d u r e calculated (Fig. 15.9g  date  of  the  immature  duration  time  that  t h e body s i z e s o f f i s h  Examination  the were  t h e GSI v a l u e was e q u a l t o 0.1  of  the  fish at this point immature  s i n c e t h e r e was no GSI v a l u e t o u s e  on w h i c h  i t s  c o n d i t i o n s t y p i c a l of that p e r i o d . Using  the  (± 0 . 9 8 ) .  and  t o d e s c r i b e t h e s i z e o f t h e f i s h and  o f back c a l c u l a t i o n ,  at  window  5 ) . The mean s i z e o f t h e m a t u r i n g  difficult  of  began  by  o f t h e d a t a , h o w e v e r , i n d i c a t e d t h a t no d e t e c t a b l e  increase  was  a  reference  then more  as  defined  f i s h present  i f fish  simply  without  'window',  increase  that  before  any  examination It  one y e a r  the  was  f i s h was more  as  a  reference  t o c a l c u l a t e body s i z e . A l s o , o n l y s m a l l numbers  fish  were  recorded  on  each  sample  date.  The  25  comparison  of mature  a n d immature  f i s h was f u r t h e r c o m p l i c a t e d  by t h e p o s s i b l e g e n e t i c a l l y c o n t r o l l e d r a t e w h i c h c o u l d e x i s t between In that:  differences  t h e mature  groups.  experiment  indicated  ( 1 ) t h e GSI began t o a c c e l e r a t e one date of spawning,  growth  a n d immature  summary, t h e r e s u l t s o f t h e f i r s t  actual  in  year  prior  t o the  (2) a d e f i n i t e window l a s t i n g p a r t o f  May, a l l o f J u n e a n d p a r t o f J u l y e x i s t e d , a n d ( 3 ) t h e weight of f i s h a t s t a r t i n g  average  t i m e was 15.9g (± . 9 ) .  EFFECTS OF GROWTH RATES AND DIFFERENT STOCKS The  purpose  of  this  i n c i d e n c e of p r e c o c i o u s limiting  growth  differences results  was  development  rates,  were  and  apparent.  confounded  "furunculosis" Nevertheless,  on  e x p e r i m e n t was t o d e t e r m i n e i f t h e could  secondly However,  be  to  controlled  by  determine i f stock  interpretation  of  the  by t h e p o s s i b l e e f f e c t o f t h e d i s e a s e  the  growth  differences  in  rate  of  growth  the  rate  Pennask  stock.  were a p p a r e n t f o r  h e a l t h y d o m e s t i c a n d P r e m i e r s t o c k s , a s w e l l a s f o r some  ration  groups  ration  (Table I I ) .  By A u g u s t  1977,  the  g r o u p grew t o an a v e r a g e s i z e o f 2 3 9 g , and  domestic  high  t h e medium g r o u p t o 178g  t h e low r a t i o n group t o I23g. T h i s c o n t r a s t s markedly  t h e s i z e o f t h e P r e m i e r s t o c k w h i c h was 4 7 . l g , 34.3g a n d for  corresponding  differences it  was  Thus,  f o r whatever  to  examine  as o r i g i n a l l y  the  incidence  33.8g  reason, large  i n g r o w t h r a t e were o b s e r v e d among some g r o u p s  possible  development  rations.  with  and  of  precocious  in  the  planned.  A n a l y s i s o f t h e p r e c o c i o u s male d e v e l o p m e n t  above  T a b l e I I . D a i l y growth s l o p e s c a l c u l a t e d f o r (Body Weight) held at d i f f e r e n t ration l e v e l s .  Stock Domestic  Pennask  Premier  Ration (% Body Wt/Day)  I n i t i a l Weight  (g) (± SE)  VS Time f o r t h r e e s t o c k s o f rainbow t r o u t  F i n a l Weight  (g) (± SE)  4.0 4.0 2.0 2.0 1.0 1.0  10.6 13.8 13.1 14.0 11.5 11.3  (1.3) (0.6) (0.9) (0.5) (0.4) (0.4)  4.0 4.0 2.0 2.0 1.0 1.0  10 10 10 9 8 10  6 9 2 0 .1  (1.3) (1.0) (0.6) (0.9) (0.9) (1.3)  20.3 17.0 18.5 17.8 13.8 16.1  ( 2.2) ( 2.0) (2.1) ( 2.7) ( 1.7) ( 3.0)  4.0 4.0 2.0 2.0 1.0 1.0  11 19 12 13 12 11  6 2 5  (1.2) (1.6) (1.5)  46.1 48.2 33.5  5  (1.5)  35.0  2 8  (1.3) (1.4)  29.8 37.9  ( ( ( ( ( (  8  249.5 (14.8) 228.2 (15:4) 170.6 (11.1) 185.4. ( 8.2) 136.6 ( 8.5) 110.2 ( 5.2)  6.6) 3.8) 4.3) 5.1) 2.0) 4.3)  Regression 1.65 1.65 1.38 1.45 1.25 1.16  X  X  -2 -2 -2 -2 10  1.73 1.31 1.92 2.00 1.95 2.16  x  1 0  4.05 4.86 3.41 4.39 4.11 - 4.20  X  X x X X  X X X X X  X X X  1  0  1 0  10  10  10  2  3 -3 -3 -3 10 1  0  1 0  1 0  1 0  3  1 0 1 0 1 0  1 0  -  -3 -3  -  X  1 0  X  10  3  Slope  (± SE)  (3.51 (6.88 (3.12 (4.04 (4.42 (6.20  X  (3.74 (3.31 (3.27 (4.60 (5.65 "(4.05  X  (8.32 (3.69 (4.35 (4 .26 (2.66 (4.03  V  x X X X x  X X X X X  X X X X X  -3, 10 -3| 10 -4! 10 10 10 -4: 10  >:!  10 10 -4 10 -4, 10 -4' 10 -4 10 10 10 •Si 10 .10 -4! 10 - 4 ! -4: 10  cn  27  groups III).  showed d i f f e r e n c e s d e p e n d e n t on s t o c k a n d The  contain  domestic any  experiment growth  strain (fall  maturing  on F e b r u a r y 23,  rates  were  at  1977,  several  fish.  This indicated  fish  was  of  fish  spawning)  either  the  was  (Table  found  not  t e r m i n a t i o n of t h e fact  that the  incidence  that  different  of  to  first their  that observed f o r the  much l e s s t h a n i n t h e w i l d  gonadal development  was  d e s p i t e the  times  ration  wild  precocious  s t o c k s or t h a t the  timing  i n these domesticated  fall  spawners. I n t h e s e c o n d p h a s e of t h e e x p e r i m e n t , t h e r e m a i n i n g from  the  Premier  and t h e d o m e s t i c  s t o c k were under  conditions  i n the Abbotsford f a c i l i t y  of  s t o c k s at t h i s time i n d i c a t e d  t h e two  stock  (c.60%)  a  observed to that fall  spawning  group, a w e l l  similar  defined  the  compared w i t h Clearly,  the  considerable  high 14%  markedly  relationship  between  rates  and  was  group  effect  confirmed  in  spring  spawning  initiated  wild  a  3%  the  Premier  growth  different  a t age  from  rate  1  the  and  matured  i n t h e low  was  between  development.  that the f a l l  the  ration.  spawners  relationship  manner  Whereas  was  (Table I V ) .  fall  apparent  strains.  gonad development  the  d i f f e r e n t . In t h i s  r a t e s of p r e c o c i o u s  From t h e s e r e s u l t s , i t was s t o c k behaved i n  Sampling  5 1 % of t h e male f i s h  the apparent  f a s t g r o w t h , o r body s i z e , and  domestic  observed  i n t h e medium r a t e s and  ration  for  23.  However, t h e d a t a  s t o c k was  i n c i d e n c e of s e x u a l development For  that  different  l e v e l of p r e c o c i o u s development  recorded e a r l i e r . domestic  u n t i l August  fish  than spring  approximately  spawning the  two  spawners one  year  28  Table I I I . P r o p o r t i o n s of p r e c o c i o u s males found i n groups of t h r e e s t o c k s r a i n b o w t r o u t r e a r e d f r o m J u l y 1976 a t three d i f f e r e n t ration l e v e l s . Ration (% Body Number wt/Day) S a m p l e d  Stock  Number of Males  Number of Precoc ious Males  %  Precoc:  Premier  4.0 4.0 2.0 2.0 1 .0 1 .0  75 75 75 75 75 75  37 53 46 50 56 44  22 45 28 34 33 25  59 85 61 68 59 57  Pennask  4.0 4.0 2.0 2.0 1 .0 1 .0  1 60 86 1 00 85 1 00 75  50 46 46 41 51 39  5 3 2 3 2 1  10 7 4 7 4 3  Domestic  4.0 4.0 2.0 2.0 1 .0 1 .0  80 80 80 80 80 80  36 54 45 45 56 44  0 0 0 0 0 0  0 0 0 0 0 0  prior  spawning,  to  the  fall  spawners  appear  d e v e l o p m e n t a t age 1.5 ( i . e . 6 months p r i o r both s t r a i n s different  developed  ages  and  during the spring at  a  different  spawning.  A second major  difference  size  the  relation  of  fish  discussed e a r l i e r . the  mean  in  I t was c l e a r  initiate  t o spawning).  of the  year,  Thus,  but  the  to  the  photoperiod  critical window  from t h e d a t a i n Table I I  sizes  of the low r a t i o n  110.2g) was w e l l  above t h e c r i t i c a l  at  time r e l a t i v e t o a c t u a l  related to  to  domestic size  groups  calculated  that  (I36.6g and f o r the  29  Table  IV.  P r o p o r t i o n s of p r e c o c i o u s male rainbow trout in groups f r o m two s t o c k s r a i s e d f r o m J u l y 1976 u n t i l August 1977 at three different ration levels. Growth slopes f o r the p e r i o d February 1977 t o A u g u s t 1977 a r e g i v e n . Ration (% Body wt/Day)  Stock Premier  Growth Slope (±1SE)  4% 2% 1%  Domestic  4% 2% 1%  Premier  stock  clearly  No. o f Males  No. o f Precocious Males  3.24 (1.10) 3.67 (1 .67) 3.60 (0.93)  34  20  59  91  57  63  63  38  60  13.70 (1.05) 75.40 (1.22) 4.75 (0.93)  35  18  51  29  4  14  39  1  3  % Precocious  ( l 0 - 2 0 g ) , y e t o n l y 3% o f t h i s g r o u p m a t u r e d .  indicated  a  stock  dependent  critical  This  s i z e of major  proportions. Throughout  the  above  analysis,  large  variation  observed  in  many f i s h  i n t h e low r a t i o n g r o u p s were l a r g e r t h a n  fish  the s i z e of f i s h w i t h i n groups t o the degree  i n t h e medium and h i g h g r o u p s .  sample,  the  compared  f o r groups having  fish  mean  weights  of  In  mature  significant  was that  the s m a l l e r  t h e , August  26,  1977  and  fish  were  immature  numbers  of  precocious  (Table V ) . This  analysis  confirms  the r e s u l t s  and more c l e a r l y d e m o n s t r a t e s t h e  very  f r o m t h e g r o u p means  large  differences  in  30  T a b l e V.  Comparison o f mean w e i g h t s o f m a t u r e and immature male t r o u t f o r groups h a v i n g s i g n i f i c a n t p r e c o c i o u s development.  Stock  Ration  Premier Premier Premier Domestic  High Medium Low High  Mean W e i g h t (g) M a t u r e (n) Immature (n) 91.27 87.88 73.09 755.32  (21) (60) (40) (17)  34.62 42.28 41.98 620.11  * p < .05  growth Thus, of  (12) (32) (25) (18)  this  ** p <  stocks related  growth  and  different  used  different  critical  for initiation  stage i n t h e i r  EFFECTS OF  whether  in  s t r a t e g y shown by f a l l  are  The  differences  life  5.07** 6.60** 5.06** 2.26*  development.  on g r o w t h r a t e o r body s i z e , to both h e r i t a b l e  dependence differences  capability size,  spawners  and  in  for  fast  finally  the  which  the  of gonadal development  history  relative  (calc)  .01  s e t of e x p e r i m e n t s d e m o n s t r a t e the s t r o n g  s e x u a l development  t  31 90 63 33  (even w i t h i n groups) which r e l a t e t o s e x u a l  between  cues  df  to  same  but a t a  spawning.  PHOTOPERIOD ON GONADAL DEVELOPMENT  first the  o b j e c t i v e of t h i s experiment incidence  and  was  to  s t a g e s of development  determine for natural  p h o t o p e r i o d and s i m u l a t e d n a t u r a l g r o u p s were t h e same. F o r t h e 200  fish  m a l e s was the  i n each of the f o u r groups, the p r o p o r t i o n of m a t u r i n g 27% and 34% i n t h e o u t d o o r t a n k s and 3 3 % and  indoor  simulated  treatments.  While  there  44%  were  in some  31  d i f f e r e n c e s between g r o u p s , expected Chi  variation  square  and  can  be  Although  understood  w e i g h t s o f t h e male f i s h with  were  not by  the  range  significant,  examination  of  of ina  these t h e mean  i n e a c h o f t h e f o u r g r o u p s . The  group  t h e h i g h e s t p r o p o r t i o n o f m a l e s a l s o h a d t h e h i g h e s t mean  weight  (44% p r e c o c i o u s and 26.0lg  groups  with the lowest p r o p o r t i o n s of  33%)  also  had  20.47g  (± 2 . 0 9 ) ,  these  groups  and  within  were n o t s i g n i f i c a n t l y d i f f e r e n t  analysis.  differences  they  the  lowest  (± 3 . 0 8 ) ) . S i m i l a r l y ,  mean  respectively.  mature  weights  The  22.63g  i n d i c a t e d no d i f f e r e n c e s  outdoor  groups,  respectively)  spermatogenesis.  In  analysis  the  later  summary,  of  i n stage of development a n d 44 s a m p l e s  almost a l l the i n d i v i d u a l s  showed  ( 2 7 % and  (± 2.22) a n d  histological  f r o m 32 s a m p l e s f r o m t h e i n d o o r g r o u p s  the  males  t h e two  stages  i t can  be  from  ( 9 1 % and 95%,  4  and  5  of  concluded that the  s i m u l a t e d n a t u r a l p h o t o p e r i o d t r e a t m e n t was i n a l l d i s c e r n a b l e ways s i m i l a r Major comparison light groups.  to the outside natural photoperiod treatment. differences  in  development  between f i s h m a i n t a i n e d  cycle  and  those  in  Some o f t h e t a g g e d  their  tags  during  still  available  to  the  on  a  expected  constant  on  natural  i n the  experiment,  seven-hour  group  but s u f f i c i e n t  comparison.  The  mature  fish  appeared  ( 1 9 % f o r seven-hour  lost  fish  incidence  u s i n g a C h i square a n a l y s i s even though photoperiods  a  seven-hour  p r e c o c i o u s d e v e l o p m e n t b e t w e e n t h e two t r e a t m e n t g r o u p s significant  in  t h e n a t u r a l and s i m u l a t e d n a t u r a l  fish  allow  were  fish  32%  for  of  was n o t raised  t o have s u b s t a n t i a l l y and  were  more  natural).  32  Similarly,  there  between  a l l  was  those  photoperiod  and  no  fish  later  is  difference treated  i n the percentage  with  a  mature  seven-hour  light  e x p o s e d t o n a t u r a l p h o t o p e r i o d , and  controls.  It  concluded,  therefore,  treatments  c o u l d n o t be d e m o n s t r a t e d  that  to a f f e c t  the  photoperiod  the  i n c i d e n c e of  p r e c o c i o u s sexual development. It se  was  and  p o s s i b l e t h a t p h o t o p e r i o d c o u l d a f f e c t growth  secondarily,  differences  in  precocious  frequency  which  development. were  However,the  observed  c o u l d not  e x p l a i n e d on t h e b a s i s o f s i z e a l o n e . Of a l l g r o u p s , raised  on  seven  41.06g (± 3 . 4 7 ) , precocious the f i s h  but  males  found  hours had  the  experiment  at  and  supports  the  (p  photoperiod  lowest  of the  end,  than  the  largest  fish  frequency  of  groups  experiment  were  immature  males.  does not  However,  significantly  a  the This  the p r e v i o u s s u g g e s t i o n t h a t mature f i s h faster.  be  fish  < .05), both a t the b e g i n n i n g of  l a r g e r o r a t l e a s t h a v e grown  of  second  t o be m a t u r e a t t h e end larger  light  were t h e s e c o n d  the  ( 1 9 % ) . Even s o , i n a l l n i n e t r e a t m e n t  significantly  further  of l i g h t  per  are  seven-hour  change the  incidence  examination  provided  p r e c o c i o u s sexual development. The  evidence change  results  of  the  histological  t h a t , a l t h o u g h a seven-hour l i g h t the  fish  f o u r and  five  not  i n c i d e n c e of p r e c o c i o u s development, i t does d e l a y  the p r o c e s s of spermatogenesis. control  p h o t o p e r i o d does  on  of  the  experiment  n a t u r a l p h o t o p e r i o d were p r i m a r i l y a t  (90-95%);  a r e p r e s e n t and  A t t h e end  that i s , large  numbers  the breakdown of the t e s t i s  of  stages  spermatids  s t r u c t u r e towards a  33  fully the  f u n c t i o n a l m a l e was fish  on  imminent or complete.  a c o n s t a n t seven-hour  light  By c o n t r a s t , i n  p h o t o p e r i o d none  r e a c h e d t h e s e s t a g e s and a l l m a t u r i n g males were a t s t a g e s and from  t h r e e . As e x p e c t e d , by t h e end seven-hour  were now  light  of August  those f i s h  t o a n a t u r a l p h o t o p e r i o d i n May  p r e d o m i n a t e l y a t s t a g e s f o u r and The  J u l y and A u g u s t  were somewhat b e h i n d and on a v e r a g e  Therefore,  t h r e e , and it  is  exposed  (71%  respectively).  s t a g e s two and  fish  five  u n d e r y e a r l i n g s on a s e v e n - h o u r  change  that  light  had  It  to successful  spawning  June 100%,  59%  h o l d i n g rainbow  photoperiod  delayed  i s n o t known f r o m t h e s e e x p e r i m e n t s  critical  and  at  five.  during  t h e p r o p o r t i o n of m a l e s which p r e c o c i o u s l y  Rather, such a p h o t o p e r i o d treatment  removed  and  t i m e t h a t a " d e c i s i o n t o spawn" t h e f o l l o w i n g y e a r was not  two  to a natural photoperiod in  41% a t s t a g e s f o u r a n d concluded  had  trout the  made d i d mature.  spermatogenesis.  whether such a d e l a y i s  the f o l l o w i n g  year.  34  DISCUSSION The  purpose  effects  of  o f t h e a b o v e e x p e r i m e n t s was  growth  on t h e i n i t i a t i o n  rate, ration,  of gonadal  m a t u r a t i o n of the t e s t i s The  first  development the  was  For  fall  the  six  period  for  in  at  an  f o r reaching  However,  the s p r i n g f i s h  which  form. which  gonad  spawners. gonad  For  weight  t h e p e r i o d b e t w e e n l a t e May fish  age  is  exactly  run o c c u r r i n g  of  final  spawners  1.5  one  in  years.  gonad s i z e was  a n d one y e a r  examination  and year  mid-June.  in  GSI  Thus,  the  a maximum o f  for  of the p a t t e r n  revealed a decline  upon f u r t h e r a n a l y s i s was  t e s t i s growth  subsequent  gonads began t o d e v e l o p a t a p p r o x i m a t e l y t h e  months f o r t h e f a l l  spawners.  fall  t h e r a t i o o f body w e i g h t t o  same t i m e o f y e a r b u t required  the  the p e r i o d during  peak o f t h e s p a w n i n g  spawners,  the  and p h o t o p e r i o d  and  s t a r t e d f o r b o t h s p r i n g and  began t o i n c r e a s e d u r i n g  to  examine  i n t o a f u n c t i o n a l l y mature  e a r l y J u l y , which f o r Premier Lake prior  stock  development  experiment d e f i n e d  s p r i n g spawners,  (GSI)  genetic  to  the  of  spring  development  after  August,  found t o r e s u l t from a d e c l i n e  r a t e , accompanied  by an  increase  in  somatic  growth r a t e . Thus, a p p r o x i m a t e l y a f o u r - t o six-month p e r i o d growth  was  required  b o t h s p r i n g and spring  fish,  fall  f o r the t e s t i s spawners.  The  to reach ultimate s i z e i n  d i f f e r e n c e was  that  t h e s i x - m o n t h p e r i o d o f g r o w t h was  in  effect energy  of  this  was  followed  strategy  i m m e d i a t e l y by  i s that  the  f o l l o w e d by a  s i x - m o n t h p e r i o d of r e l a t i v e dormancy whereas i n t h e f a l l gonadal development  of  fish,  spawning.  the f i s h are able  i n t o b o t h g o n a d a l and s o m a t i c growth d u r i n g  The  to d i r e c t  the  period  35  of  t h e y e a r when c o n d i t i o n s f o r g r o w t h a r e The  the  f a c t that the i n i t i a t i o n  period  from  seasonal  late  maximum  of  May  to  food  appropriate.  of development  early  July,  abundance,  occurs during  just  before  i s consistent with  g e o m e t r i c n a t u r e of growth of t h e gonads. In o t h e r words, energy  required  testis, early  the  f o r growth  i s a f u n c t i o n of  commencement  of  periods  of  pronounced stable  GSI  under  in  nature  t h e GSI  sufficient GSI  August  The  would not change  was  confirmed  by  proportion  change  during  Furthermore, apparent  many  critical  more  a  the  reality  r a t e s and  elevated  the somatic  growth  and  as  a  appreciably.  experiments s i n c e the significantly  during  In the w i l d ,  p r e s e n c e o f " t i m e window" f o r t h e i n i t i a t i o n  development  the  was  be e x p e c t e d t o d e c l i n e w i t h t h e t e s t i s g r o w t h t h e GSI  of  w e l l not i n c l u d e a drop i n  s o m a t i c g r o w t h . R a t h e r , as w i n t e r e n c r o a c h e s  result  since  must o c c u r  i n the h a t c h e r y i s not  p a t t e r n may  the  f o o d . However, i t  after  b r o u g h t a b o u t by d e c l i n i n g t e s t i s g r o w t h  would  size  development  these laboratory c o n d i t i o n s .  food r a t i o n a v a i l a b l e  in  the  growth phase i s t o o c c u r  warm t e m p e r a t u r e s and  i s p o s s i b l e t h a t the d e c l i n e  and  gonadal  i n the year i f the major  the  the of  the  results maturing  course  fish  which  were  size  later  in  of  observed the  year  of  of  testis  the  first  fish the to  did  not  experiment. reach  d i d not  the  develop  sexually. The  first  experiment  w h i l e the second the  factors  e s t a b l i s h e d t h e p r e s e n c e o f a window,  experiment  influencing  was  directed  the i n i t i a t i o n  towards  determining  of t e s t i s  development  36  d u r i n g the time  window.  Results  clearly  demonstrated  variable  a s s o c i a t e d w i t h development.  the  suggestion  the  of  of  the  importance  Mackinnon  ration  of  body  This  and  experiments size  gives  and  that  once  fish  Donaldson  development  is  initiated.  differences  in  the  reach  In  the  incidence  o b s e r v e d as a f u n c t i o n of r a t i o n the  other  ration  stocks  were  among g r o u p s  observed  differences  the  in  (1976)  of  mature  t r e a t m e n t was fish  size  and  1Og  20g  smaller  this  m a t u r e i f s i z e was The  due  domestic  was  for  fish,  l a t e May  Premier  f i s h and  as  Domestic  evidenced strains;  by  large  of  to early  different  the  larger average  of  ration  association  July.  of  f o r the  r a n g e was  betwen  Thus,  fish  n o t be e x p e c t e d  to  variable.  below  the  from  the  critical  i n c i d e n c e of m a t u r a t i o n  s t o c k s have d i f f e r e n t  comparison  the  these  that  s u p p o r t e d by t h e r e s u l t s  a v e r y low  of  in size  Back c a l c u l a t i o n s size  from  Despite  independent  the o n l y d e t e r m i n i n g  a b o v e c o n c l u s i o n was  gonad  Results  d i d support the concept  s i z e a t t h a t time would  observed. C l e a r l y ,  sizes  size.  stock.  P e n n a s k s t o c k s i n c e most o f t h e f i s h w e r e size  size  t o the f a i l u r e  t h a t the c r i t i c a l  f o r the p e r i o d  than  and body  t e s t i s development.  stock suggested  size  strain  u n e q u i v o c a l i n demonstrating the  with  that  be  the c o n s i s t e n t d i f f e r e n c e s  immature  to  o f p r e c o c i o u s d e v e l o p m e n t were  t o mature. A comparison  Premier and  critical  domestic  clear  the  evidence  f i s h were more l i k e l y size  less  treatments to produce  a  the  credence  p r e c o c i o u s s e x u a l d e v e l o p m e n t i n m a l e p i n k s a l m o n may related  as  between  the  critical  Premier  c o n s e q u e n t l y , t h e P e n n a s k f i s h may  and  a l l have  37  been w e l l b e l o w t h e data  there  i s no  however, t h a t this  escapements  as  and  While exists, the  critical  not of  genetic  example, i t  e t a l . (1976) and  most i n s t a n c e s , a p p e a r s as the  i f the  assertion  possible  i n d e p e n d e n t of  select  at  age  the  establish critical  manifestation  that  for  the The  to  and  i t is  at  least  is  to  separate  influences  within  that  age  the  at  a  given  of  g r o w t h r a t e , as  a heritable  first  suggested that  first  first  critical  spawning i s  s i z e as  in  a heritable  trait  would  under  selection  f a s t g r o w t h , an  for  and  in  glance,  size  verification is  strict i t is  required. not  early  just age  inherited  t o d e t e r m i n e i f the  s l o w g r o w i n g g r o u p s was  the  whether exposure to a n a t u r a l  a at  e x p e r i m e n t would have t o  be  growth  critical  size  addressed  was  same.  f i n a l q u e s t i o n t o w h i c h t h i s s t u d y was  investigate  time,  a p p a r e n t l y c o n f l i c t i n g view that  subsequently  f a s t and  annual  development c l e a r l y  designed to c l a s s i f y f i s h according to t h e i r potential  for  i n the  f o r f a s t e r g r o w t h . At  of a s i m u l t a n e o u s  s p a w n i n g and  appear,  for early maturation could,  s i m p l y s i z e r e l a t e d ; , however, f u r t h e r  first  present  these  5.0g  N a e v d a l e t a l . ( 1 9 7 8 ) , but  c o n c e p t of  that  with  than  experiments  size  which s e l e c t  also  genetic control  To  smaller  200g  in these  is  by  link  only  and  is inherited  it  not  s i z e f o r Pennask f i s h  possible  conditions  From  Domestic s t r a i n .  spawning  nature  s i z e was  a r e l a t i o n s h i p b e t w e e n s i z e and  effects  Moller  stock.  knowing f o r c e r t a i n . I t would  weigh  f o r the  i t was  s t o c k . For  size for that  p r e c o c i o u s males are  may  the  h i g h as  of  critical  since  apparent that not  way  the  s t o c k and  critical  photoperiod  during  38  the or  t i m e window when t h e t e s t i s  whether o t h e r mechanisms c o n t r o l l e d  development. Since the frequency significantly it  can  be  different safely of  photoperiod  conditions  probably  testis  precludes  a s an a p p r o p r i a t e sexual the  factors  whether  method  results  deVlaming  in  they  presented  et  the  This  manipulation incidence  of  the  internal  controlling  be g r o w t h r a t e , body s i z e o r some o t h e r i n f l u e n c e t h e age a t f i r s t have  also  confirmed  t h e a s s e r t i o n of  the i n i t i a t i o n  of environmental  spawning.  of  gonadal  factors.  plausible  of  t h e r e l a t i o n s h i p between body  precocious  physiological  development.  of  experiment.  the  m a t u r a t i o n , we a r e l e f t w i t h s e v e r a l o t h e r  a  The  critical  would correspond  quite  initiation  of  t h e onset  onset  could  the  i scontrolling  explanations. Clearly,  f i s h which  this  i t i s not p h o t o p e r i o d which  gonad  trout  r e a r e d f i s h and u n d e r l i n e s  of  (1974) t h a t f o r s a l m o n i d s  Since  reaching  hatchery  significance  d e v e l o p m e n t was i n d e p e n d e n t  the  in  not  groups,  independent  for controlling  i n h e r i t e d mechanism which The  is  was  and c o n t r o l  f o r rainbow  development applied  males  the u s e f u l n e s s of photoperiod  precociousness  considerable  of precocious  that  was e s s e n t i a l  the i n i t i a t i o n of t e s t i s  between t r e a t m e n t  concluded  initiation  of  began t o d e v e l o p  conceivably  of spermatogenesis  the p i t u i t a r y  gland  a l . ( 1 9 7 5 ) who f o u n d  development age  would  i s mandatory  size  indicate  t o the pubescent be  heritable.  years  that f o r a  individual of  the  This i s confirmed  variety  testis  humans  Furthermore,  appears t o r e q u i r e  (Dodd, 1 9 7 2 ) .  that  before  p h y s i o l o g i c a l age o f an  of  and  the  function by C r i m  salmonids  the  39  pituitary into  was  necessary  primary  f o r the t r a n s f o r m a t i o n of  spermatocytes.  w o u l d a p p e a r t o be t h e key testes  maturation.  pituitary  i s under  (Donaldson,  Therefore, gonadotropin  which  Since the  1973),  unlocks  the  gonadotropin  direct  it  is  spermatogonia  control  reasonable  to  r e q u i r e d a t t a i n m e n t o f a p h y s i o l o g i c a l age  inhibitors  release  of  the  control  Therefore, I conclude rainbow  trout  mechanism that  associated  time  rate prior  window,  is  to t e s t i s  time  t h a t t h i s a t t a i n m e n t of a often  associated  with  that certain  a  rapid  development.  from  there  p r o s p e c t i v e why  or  are an  That  good  reasons  start  testis  r e s u l t s of t h i s  t o d e v e l o p a t one some i n t e r n a l  question  a  i n d i v i d u a l upon r e a c h i n g t h e  s h o u l d not  e v e n l a t e r . The  t h e r e i s presumably period.  point  although  show t h a t f i s h o n l y s t a r t and  the  observed  r e q u i r e d p h y s i o l o g i c a l age November  to  t h i s o n l y e x p l a i n s the b e g i n n i n g of the  bioenergetical  in  matures  first  release.  the  axis  at  with  hypothalamic-  gonadotropin  age  the  i s , i n p a r t , a f u n c t i o n of t h e t i m e a t w h i c h  i s r e l e a s e d and  However,  that  in  t h r e s h o l d a t an e a r l y age growth  the  the  maturation  hypothalamic-pituitary gonadotropin  for  of  hypothalamus  the m a t u r a t i o n , t o a f u n c t i o n a l c o n d i t i o n , of the pituitary  from  believe is  activity  time  development study of  clearly  the  year  rhythm which d e f i n e s the  lends  itself  to  further  investigation. It  would  commercial  fish  appear,  t h e r e f o r e , t h a t t h e h a t c h e r y manager o r  f a r m e r may  w e l l be a b l e t o r e d u c e  of p r e c o c i o u s s e x u a l development  of  males  by  the i n c i d e n c e at  least  two  40  separate if  not c a u s a l ,  window For  methods. F i r s t l y ,  and  relationship  restrict  the commercial  costs  and  a  manager i t may Alternatively,  associative,  growth  the  result he may  their  capacity  in  will  lower  clearly  result  in  survivals  for  added fishery  stocked  fish.  s e l e c t i v e l y breed f o r l a t e maturing with  or  f o r growth.  be c l e a r l y e s t a b l i s h e d  independent  from  fish  concern  for  I n any e v e n t , i t i s d e s i r a b l e  whether the a s s o c i a t i o n  body s i z e a n d e a r l y  these experiments  time  t o m i n i m i z e t h e s i z e of h i s f i s h .  lower p r o d u c t i o n c a p a b i l i t y , and f o r the  in association  growth or large  d e p e n d upon t h e  b e t w e e n body s i z e d u r i n g  farm, t h i s  either  it  he may  m a t u r a t i o n as  i s s t r i c t l y associative  or a l s o  between  that rapid  observed causal.  in  41  LITERATURE CITED A l l i s o n , L.N. 1951. D e l a y o f s p a w n i n g o f e a s t e r n b r o o k t r o u t by means o f a r t i f i c a l l y p r o l o n g e d l i g h t i n t e r v a l s . P r o g . F i s h . C u l t . , 13:111-116. Aim,  G. 1959. C o n n e c t i o n s b e t w e e n m a t u r i t y , s i z e a n d age i n f i s h e s . I n s t . F r e s h w a t . Res. D r o t t n i n g h o l m , 40:5-145.  B i l t o n , H.T. 1 9 7 1 . A h y p o t h e s i s o f a l t e r a t i o n o f age o f r e t u r n i n s u c c e s s i v e g e n e r a t i o n s o f Skeena r u n sockeye. J . F i s h . Res. B d . C a n a d a , 2 8 : 5 1 3 - 5 1 6 . Bonham K. a n d L.R. D o n a l d s o n . 1972. Sex r a t i o s a n d r e t a r d a t i o n of g o n a d a l d e v e l o p m e n t i n c h r o n i c a l l y gamma-irradiated c h i n o o k s a l m o n s m o l t s . T r a n s . Am. F i s h . S o c , 101:428434. B r e t t , J.R.; J . E . _ S h e l b o u r n ; C T . Shoop. 1969. G r o w t h r a t e a n d body c o m p o s i t i o n o f f i n g e r l i n g s o c k e y e s a l m o n , i n r e l a t i o n t o temperature and r a t i o n s i z e . J . F i s h . Res. Bd. C a n a d a , 2 6 : 2 3 6 3 - 2 3 9 3 . C a m p b e l l , R.N. 1 9 7 1 . The g r o w t h o f brown t r o u t , Salmo t r u t t a L., i n n o r t h e r n S c o t t i s h l o c h s w i t h s p e c i a l r e f e r e n c e t o t h e i m p r o v e m e n t o f f i s h e r i e s . J . F i s h . B i o l . 3:1-28. C o r s o n , B.W. 1955. F o u r y e a r s p r o g r e s s i n t h e u s e o f a r t i f i c a l l y c o n t r o l l e d l i g h t t o induce e a r l y spawning of b r o o k t r o u t . P r o g . F i s h . C u l t . , 17:99-102. C r i m , L.W., E.G. W a t t s ; D.M. E v a n s . 1975. The p l a s m a gonadotropin p r o f i l e during sexual maturation i n a v a r i e t y o f s a l m o n i d f i s h e s . Gen. Comp. E n d o c r i n o l . , 27:62-70. Dodd, J.M. 1972. The e n d o c r i n e r e g u l a t i o n o f g a m e t o g e n e s i s a n d gonad m a t u r a t i o n i n f i s h e s . Gen. Comp. E n d o c r i n o l . S u p p l . , 3:675-687.  42  D o n a l d s o n , E.M. 1973. R e p r o d u c t i v e e n d o c r i n o l o g y o f f i s h e s . Amer. Z o o l . 13:909-927. D o n o v a n , B.T. a n d J . J . v a n d e r W e r f f t e n B o s c h . 1965. P h y s i o l o g y o f P u b e r t y . I n : 'Monographs o f t h e p h y s i o l o g i c a l s o c i e t y ' (No. 1 5 ) , e d s . H. B a n c r o f t , H. Dawson, W.D.M. P a t o n . F l a i n , M. 1970. P r e c o c i o u s m a l e q u i n n a t s a l m o n ( O n c o r c h y n c h u s t s h a w y t c h a ) i n New Z e a l a n d . New Z e a l a n d J . M a r . F r e s h w . Res., 4:217-222. F u n k , J.D. a n d E.M. D o n a l d s o n . 1972. I n d u c t i o n o f p r e c o c i o u s s e x u a l m a t u r i t y i n male p i n k salmon. Can. J . Z o o l . , 50:1413-1419. G a r d n e r , M.L.G. 1976. A r e v i e w o f f a c t o r s w h i c h may the sea-age and m a t u r a t i o n o f A t l a n t i c salmon s a l a r ) . J . F i s h . B i o l . 9:289-327.  influence (Salmo  H a n s o n , J . A . a n d R.H. W i c k w i r e . 1967. F e c u n d i t y a n d age a t m a t u r i t y o f l a k e t r o u t i n L a k e T a h o e . C a l i f . F i s h & Game, 53:154-164. H a r r i n g t o n , R.W. 1959. P h o t o p e r i o d i u m i n f i s h e s . I n ' P h o t o p e r i o d i s m a n d r e l a t e d phenomena i n p l a n t s a n d a n i m a l s ' , E d . R. W i t h r o w . Amer. A s s o c . A d v . S c i e n c e P u b . No. 5 5 . W a s h i n g t o n , D.C. H a s k e l l , D.C. 1948. G r a p h i c a l method o f p r e s e n t i n g d a t a on t h e growth of t r o u t . Prog. F i s h . C u l t . 10(2):59-61. H a z a r d , T.P. & R.E. E d d y . 1950. M o d i f i c a t i o n o f t h e s e x u a l c y c l e i n t h e b r o o k t r o u t ( S a l v e l i n u s f o n t i n a l i s ) by c o n t r o l o f l i g h t . T r a n s . Am. F i s h . S o c , 80:158-162. H e n d e r s o n , N.E. 1963. I n f l u e n c e o f l i g h t a n d t e m p e r a t u r e on t h e r e p r o d u c t i v e c y c l e of t h e e a s t e r n brook t r o u t ( S a l v e l i n u s f o n t i n a l i s ) . J . F i s h . R e s . B d . C a n a d a , 20:859-897. H i r o s e , K. & E.M. D o n a l d s o n . 1972. B i o l o g i c a l s t u d y on o v u l a t i o n i_n v i t r o o f F i s h - I I I . The i n d u c t i o n o f i n v i t r o o v u l a t i o n of O r y z i a s l a t i p e s o o c y t e s u s i n g salmon p i t u i t a r y g o n a d o t r o p i n . B u l l . J a p . S o c S c i . F i s h . , 3897-100.  43  H o a r , W.S. Vol. N.Y. lies,  1969. R e p r o d u c t i o n . I n : F i s h P h y s i o l o g y pp. 1-72, 3, E d s . W.S. H o a r a n d D.J. R a n d a l l . A c a d e m i c P r e s s . and London.  T.D. 1974. The t a c t i c s a n d s t r a t e g y o f g r o w t h i n f i s h e s . In "Sea F i s h e r i e s R e s e a r c h " . E d s . F.R. H a r d e n - J o n e s , p p . 331-345. E l e k S c i e n c e s , London.  Iwama, G.K. a n d A.F. T a u t z . 1981. A s i m p l e g r o w t h model f o r s a l m o n i d s i n h a t c h e r i e s . T r a n s . Am. F i s h . S o c . ( I n press) . J o n e s , J.W. & J.H. O r t o n . 1940. The p a e d o g e n e t i c m a l e c y c l e i n Salmo s a l a r L. P r o c . Roy. S o c . L o n d . S e r i e s B. B i o l . Sci., 128:485-499. K a t o , T. 1975. The r e l a t i o n b e t w e e n t h e g r o w t h a n d r e p r o d u c t i v e c h a r a c t e r i s t i c s of r a i n b o w t r o u t (Salmo g a i r d n e r i ) . B u l l . F r e s h w a t r . F i s h . Res. Lab. Tokyo, 25:83-99. M a c K i n n o n , C.N. & E.M. D o n a l d s o n . 1976. E n v i r o n m e n t a l l y i n d u c e d p r e c o c i o u s s e x u a l development i n t h e male p i n k salmon. J . F i s h . R e s . Bd. C a n a d a , 3 3 : 2 6 0 2 - 2 6 0 5 . M a r u s h i g e , K. & G.H. D i x o n . 1969. D e v e l o p m e n t a l c h a n g e s i n chromosal composition template a c t i v i t y during s p e r m a t o g e n e s i s i n t r o u t t e s t e s . D e v e l o p . B i o l . , 19:397414. M c F a d d e n , J . T . 1965. Some e f f e c t s o f e n v i r o n m e n t on egg p r o d u c t i o n i n brown t r o u t . L i m n o l . O c e a n o g r . 10:88-95. M o l l e r , D.; G. N a e v d a l ; M. Holm; R. L e r o y . 1976. V a r i a t i o n i n g r o w t h r a t e and age a t s e x u a l m a t u r i t y i n r a i n b o w t r o u t . FAO T e c h . R e p t . F I R . AQ/Conf. 1976. E. 6 1 . N a e v d a l , G.; M. Holm; 0. I n g e b r i g s t e n ; D. M o l l e r . 1978. V a r i a t i o n i n age a t f i r s t s p a w n i n g i n A t l a n t i c s a l m o n ( S a l m o s a l a r ) . J . F i s h . R e s . Bd. C a n a d a , 35:145-147.  44  Nomura, M. 1963. S t u d i e s on r e p r o d u c t i o n i n r a i n b o w t r o u t w i t h s p e c i a l r e f e r e n c e t o e g g - t a k i n g . 5. D e v e l o p m e n t o f gonads and s i z e o f f i s h spawned f i r s t l y . B u l l . J a p . S o c . S c i . F i s h . , 29:976-984. O o t a , I . ; K. Yamamoto; K. T a k a n o ; T. S a k a g u c h i . 1965. S t u d i e s on t h e m a t u r i n g p r o c e s s i n r a i n b o w t r o u t ( S a l m o g a i r d n e r i ) . 2. M a t u r a t i o n o f t h e t e s t i s o f a 1-year o l d f i s h . B u l l . J a p . Soc. S c i . F i s h . , 31:597-605. O d e l , W.D. a n d R.S. S w e r d l o f f . 1972. R o l e o f t h e g o n a d s i n sexual m a t u r a t i o n . I n : ' C o n t r o l of the onset of puberty' pp 3 1 3 - 3 3 3 , E d s . M.M. Grumbach, G.D. G r a v e , F.E. M a y e r . W i l e y a n d S o n s , N.Y. P i c k f o r d , G.E. & J.W. A t z . 1957. P h y s i o l o g y o f p i t u i t a r y of f i s h e s . New Y o r k Z o o l . S o c . New Y o r k .  gland  R o b e r t s o n , O.H. 1958. A c c e l e r a t e d d e v e l o p m e n t o f t e s t i s a f t e r u n i l a t e r a l g o n a d e c t o m y w i t h o b s e r v a t i o n s on n o r m a l t e s t i s o f r a i n b o w t r o u t . U.S. F i s h & W i l d l i f e S e r . F i s h . B u l l . , 127:9-30. S c h a e f f e r , W.M. & P.F. E l s o n . 1975. The a d a p t i v e s i g n i f i c a n c e of v a r i a t i o n s i n l i f e h i s t o r y among l o c a l p o p u l a t i o n s o f A t l a n t i c salmon i n N o r t h A m e r i c a . E c o l o g y , 56:577-590. Schwassman, H.O. 1971. B i o l o g i c a l Rhythms. I n : ' F i s h P h y s i o l o g y ' , p. 3 7 1 - 4 2 8 , v o l . 6, E d s . W.S. H o a r , D . J . R a n d a l l , A c a d e m i c P r e s s . N.Y. a n d L o n d o n . S t e a r n s , S.C. 1976. L i f e h i s t o r y t a c t i c s : a r e v i e w i d e a s . Q u a r t . Rev. B i o l . 51(1):3-47. S i m p s o n , T.H. 1976. E n d o c r i n e a s p e c t s o f s a l m o n i d P r o c . Roy. S o c . E d i n . ( B ) , 7 5 : 2 4 1 - 2 5 2 .  of the  culture.  T i t a r e v , Y e . F. 1975. A c c e l e r a t i o n o f m a t u r a t i o n i n r a i n b o w t r o u t (Salmo g a i r d n e r i ) under t h e i n f l u e n c e of i n c r e a s e d w a t e r t e m p e r a t u r e . J . I c h t h y o l . , 15:507-509.  d e V l a m i n g , V.H. 1972. E n v i r o n m e n t a l c o n t r o l o f t e l e o s t reproductive cycles: a b r i e f review. J . F i s h . B i o l . , 4:131-140. d e V l a m i n g , V.H. 1974. E n v i r o n m e n t a l a n d e n d o c r i n e c o n t r o l o f t e l e o s t r e p r o d u c t i o n . I n " C o n t r o l o f sex i n f i s h e s " , Ed C.B. S c h r e c k . E x t . D i v . , V i r g i n i a P o l y t e c h n i c I n s t . , S t a t e Univ. B l a c k s b u r g , Va. Wagner, H.H. 1974. P h o t o p e r i o d a n d t e m p e r a t u r e r e g u l a t i o n o f s m o l t i n g i n s t e e l h e a d t r o u t ( S a l m o g a i r d n e r i ) . Can. J . Z o o l . , 52:219-234.  

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0095442/manifest

Comment

Related Items