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Evidence for adaptive differences in the ontogeny of osmoregulatory ability, current response and salinity… Birch, Gary J. 1987

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EVIDENCE FOR ADAPTIVE DIFFERENCES T H E ONTOGENY OF OSMOREGULATORY C U R R E N T RESPONSE AND SALINITY  ABILITY,  PREFERENCE  OF COHO SALMON, ONCQRHYNCHUS FROM C O A S T A L AND INTERIOR  IN  KISUTCH,  POPULATIONS.  by GARY J.  BIRCH  B . S c . ( H o n . ) , University of British Columbia,  1971  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF T H E REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in T H E F A C U L T Y OF G R A D U A T E STUDIES (Department of Zoology) We accept this thesis as conforming to required standard  the  T H E UNIVERSITY OF BRITISH COLUMBIA May 1987 (c)  Gary J.  Birch,  1987  In  presenting  this  degree at the  thesis  in partial  University  of  freely available for reference copying  of  department publication  this or of  his  or  the  requirements  British Columbia, I agree that the and  her  purposes may  representatives.  this thesis for financial gain  be It  shall not  granted  is be  The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date  June 18.  1987  advanced  by  the that  for extensive head  of  my  copying  or  allowed without my  Gary J . B i r c h  Zoology  an  Library shall make it  understood  permission.  Department of  for  study. I further agree that permission  thesis for scholarly by  fulfilment of  written  ii  ABSTRACT  This  thesis  examines  the  indicator  of  osmoregulatory  indicator  of  emigration  ontogeny ability),  timing)  salmon (Oncorhynchus kisutch).  and  of  plasma  current salinity  or  sodium  regulation  (an  response  (an  rheotactic  preference  in juvenile  coho  The purpose of the study was to determine  if there are inherited differences in the development of these traits between coastal  and  (Cold water  interior River)  British and  a  Columbia populations coastal  (Rosewall  of  coho.  Creek-Big  An interior  Qualicum  River)  population were monitored for the above traits throughout the year. wild and laboratory raised  groups  were included in the study.  Both  The laboratory  populations were divided into two incubation treatment  groups:  one  incubated under a coastal temperature regime, and the other incubated under an interior temperature regime.  There were no differences in the development of sodium regulatory ability between wild populations when the data were sorted by coho weight. coho,  Coastal  however, physiologically smolted after one year in the natal streams,  while interior coho smolted after at least two years of freshwater growth.  No  obvious differences were noted between wild resident populations in the timing of downstream movement or the shift in salinity preference from hypotonic to isotonic  and  hypertonic salinities.  Both of  these  behavioural responses  typically occurred in the spring (April-May) of each year. however,  Fyke net catches,  sugqested that, in addition to the spring emigrations observed in  both populations, (November).  a portion of the interior population migrated in the fall  iii  ABSTRACT  No  differences  observed  either  the  within  regulatory  ability  emergence,  and  (April-May).  in  (CONTINUED)  development  or  increased increased  between  of  laboratory  to a plateau to  sodium  smolting  in the  levels  regulatory  raised fall  ability  were  populations. and  d u r i n g the  winter  Ion  following  following  spring  There were differences between coastal and interior populations  i n the pattern of development of both nocturnal current responses and the preference coho  for isotonic or hypertonic salinities.  developed  negative  nocturnal rheotaxis  and  Interior laboratory a preference  raised  for isotonic  salinities about three months earlier (November) than laboratory raised coastal coho  (late  February-March).  Within  populations,  no  differences  were  observed i n the ontogeny of these traits in the groups reared under different temperature  regimes.  Because these interpopulation ontogenetic behavioural differences  persisted  i n fish reared under identical laboratory conditions, they probably have some genetic basis.  Such an innate component in behaviour implies an  adaptive  role and in juvenile coho these behavioural traits may allow populations to use a variety of habitats at different distances from the sea, even though a major physiological capabilities)  schedule  (in  this  case  the  development  appears to be fixed within the species.  migratory timing and salinity preference  of  ion  regulatory  Perhaps variations in  in juvenile coho evolved to assure  s u r v i v a l in a relatively unstable and often severe environment by optimizing habitat use within the constraints of an o v e r r i d i n g physiological schedule.  iv  TABLE  OF C O N T E N T S  Page  ABSTRACT TABLE  ii  OF CONTENTS  LIST  OF T A B L E S  LIST  OF FIGURES  LIST  OF APPENDICES  iv vi vii ix  ACKNOWLEDGEMENTS  x  INTRODUCTION  1  PHYSIOLOGICAL STUDY  AND  BEHAVIOURAL C H A R A C T E R S STUDIED  STREAMS  COLDWATER RIVER  4 9  9  ROSEWALL CREEK  16  BIG QUALICUM RIVER  17  S T U D Y STREAM COMPARISON  18  METHODS  21  TERMINOLOGY  21  FIELD METHODS  22  Chemical and Physical Measurements  22  Adult Coho Capture and Egg Handling  23  Wild Coho F r y Capture and Handling  24  EXPERIMENTAL  26  GROUP MAINTENANCE  Incubation and Emergence  26  Rearing of Experimental F r y  27  V  TABLE OF CONTENTS  (CONTINUED)  Page  WEIGHT AND L E N G T H MEASUREMENTS AND AGEING PROCEDURES  31  EXPERIMENTAL TECHNIQUES  32  Plasma Sodium Regulatory Ability  32  Current Response  35  Salinity Preference  40  S T A T I S T I C A L METHODS  46  DESIGN AND C A L I B R A T I O N OF EXPERIMENTS  47  Plasma Sodium Regulatory Ability  48  Current Response  51  Salinity Preference  52  Potential Effects of Size and Growth  56  RESULTS  58  Plasma Sodium Regulatory Ability  58  Current Response  68  Salinity Preference  77  DISCUSSION  85  CONCLUSIONS  97  LITERATURE CITED  100  APPENDICES  113  vi  L I S T OF T A B L E S  Table  Table Title  Page  1  Fish species composition and average coho escapement (1970-1982) and spawning times for the study streams... 14  2  Physical and chemical data from the study streams  15  3  Comparisons between resident and migrant Coldwater River coho subyearling plasma sodium concentrations  61  Comparisons of weight and length measurements among groups of physiologically smolted coho  64  Seasonal Fyke net catches of coho in the Rosewall Creek and Coldwater River  69  Comparisons of current responses between resident and migrant coho subyearlings within illumination conditions and population  72  4  5 6  vii  LIST OF FIGURES  Figure  Figure Title  Page  1  The  Coldwater River study area  10  2  The  coastal streams study area  11  3  Seasonal discharge trends for the study streams  13  4  The Fyke net used for downstream migrant sampling in the Coldwater River (Photo 1) and Rosewall Creek (Photo 2)  25  5  Seasonal temperature changes in the laboratory and study streams  29  6  Current response channel design  36  7  Salinity preference channel design  42  8  Seawater challenge test results for wild Rosewall Creek coho Seawater challenge test results for wild Coldwater River coho  9  10 11 12  13 14  59 60  Wild coho seawater challenge test results sorted by size classes  63  Seawater challenge test results for 6°C incubation, laboratory reared coho  66  Seawater challenge test results for 2°C incubation, laboratory reared coho  67  Current response coho  trends for wild Rosewall Creek 70  Current response coho  trends for wild Coldwater River 71  viii  L I S T OF FIGURES  Figure  15  16  17  18  19  20  (CONTINUED)  Figure Title  Page  Current response trends for 6°C incubation, laboratory reared coho  74  Current response trends for 2°C incubation, laboratory reared coho  75  Salinity preference trends for wild Rosewall Creek coho  78  Salinity preference trends for wild Coldwater River coho  79  Salinity preference trends for 6°C incubation, laboratory reared coho  81  Salinity preference trends for 2°C incubation, laboratory reared coho  82  ix  L I S T OF APPENDICES  Appendix  1  Appendix Title  Page  Common and scientific names of fish species found in the study streams  113  Adult coho brood stock data from Rosewall Creek and the Coldwater River  114  Egg size, incubation temperature and incubation rate by population  114  F r y emergence dates, emergent rates, emergent numbers and length and weight data  115  5  Laboratory  115  6  Geometric functional regressions of standard length on fork length and total length on fork length for wild and laboratory raised coho juveniles  116  The observed flow regime in the current response channels over the 12 month study period  117  8  Design and calibration of experiments  118  9  Salinity preference distribution modes and MannWhitney U test comparisons between test and control distributions  143  2  3 4  7  rearing conditions  X  ACKNOWLEDGEMENTS  This study was  completed under the supervision of Dr.  advice, constructive criticism and appreciated.  support  number  of my  ability to design and  Louw, conduct  to consider graduate studies.  colleagues,  assistance.  The  field  friends and assistance  family provided of  Clyde  field,  Murray,  lab  E.B.  and  techniques  Kate and  Shaw  experimental  particularly helpful. assisted  with  My  the  data  Murray and my  field  collection  Rick Taylor were  father, Trevor Birch,  for computer listing.  Alistair Blanchford  statistical analyses.  were  provided  Several friends and  comments of Dr.  contributed  design with Clyde  of  McPhail,  Dr. T.G.  particularly  to the organisation and  Margaret was  my  Without  Northcote,  appreciated.  library.  financially  was  (67-0976) awarded, in part, to Dr.  Dr. Their  N.J.  Wilimovsky  editorial  and  responsibility of the  supported  McPhail.  by  an  and  comments  readability of the final product.  positioning are the  study  direction for computer  advisors reviewed the thesis draft.  facing page numbering and This  Kevin  drive, I would never have completed this work.  Patrick Lavin and  Taylor  Discussions  lab technician during the latter stages of the study.  her help, support and  Rick  appreciated.  wife, Margaret Birch, and  summarizing  main field and  The  are  and  (Rick)  Taylor, Marvin Rosenau, Steve Cox-Rogers, Tim Slaney, Patrick Lavin, Loftus  His  were greatly  I would also like to acknowledge the interest of Dr. G.N.  experiments spurred me  clerical  McPhail.  throughout the study  University of Capetown, whose confidence in my  A  J.D.  Figure U.B.C.  N.S.E.R.C.  grant  1  INTRODUCTION  The  tendency  among  salmonids  for juveniles  to imprint  on their  natal  stream and for mature adults to return to this stream to spawn results in the formation of numerous Larkin  1972, Ihssen  population  units  maintained  through  reproductive  genetically discrete populations or stocks 1977, Horrall  that  show  1981).  temporal  recruitment  and  These  or spatial sustained  stocks  are intraspecific  integrity, through  and  at  isolation (Booke 1981, Ihssen et al. 1981).  (Simon and  that are  least  partial  Consequently, the  identification and definition of the functional characteristics of stocks are of interest  to fisheries  (Larkin Evans  managers,  aquaculturists,  1972 and 1981, Altukhov 1981).  1981, Krueger  Additionally, the stock may  evolution occurs  geneticists  and  ecologists  et al. 1981, MacLean and  be the population  (Ehrlich and Raven 1969), and therefore  unit at which  stock variation and  its adaptive significance are important in understanding the role of selection in the definition of population characteristics.  Stocks including  have  been  biochemical,  identified by  morphometric, meristic,  behavioural  characters  biochemical  or electrophoretic  provide  a  environment.  a variety  phenotypic  (Ihssen  of population calcareous,  et a l . 1981). data  description  Of these  (and possibly that  is  characteristics  physiological and traits,  cytogenetic  relatively  only the  information)  unaffected  by  Electrophoretic evidence of genetic differentiation among salmon  stocks is substantial and has been used to study relationships among stocks (Utter et al. 1973, Huzyk and T s u y u k i 1974, May 1975, Allendorf 1979).  Electrophoretic  and Utter  descriptions, however, are of little value if there are  no, or only small, differences in isozyme frequencies  among stocks.  Allendorf  2  and  Utter (1979) indicate that electrophoretic analyses  of  possible  amino  acid  substitutions  detect as little as 33%  and, i n salmonids  in  electrophoresis suggests generally low levels of heterozygosity 1980).  Indeed,  in  salmonids,  stocks  can  be  particular,  (Utter et a l .  electrophoretically  indistinguishable but still genetically differentiated and differentially adapted to their respective environments (Utter 1981).  In most characters  used  to define  stocks, the observed  variation is a  result of the interaction of genetic and environmental factors that determine phenotypic traits  (Ricker 1972, Ihssen  et a l . 1981).  together  Before the  adaptive significance of such traits and their importance to stock discreteness and  maintenance  can  be  investigated,  these  environmental  along  with  and  genetic  components must be recognized.  Morphometric and meristic characters,  calcareous  otoliths) zonation patterns often are useful and powerful discreteness and relationships among stocks.  (scales and  means of estimating  The observed variation i n such  characters, however, is not easily related to direct genetic differences and such traits can be largely a result of environmental factors and physiological constraints temperature, variation  (Martin  1949, Bock  salinity,  1980).  pH, oxygen  i n the phenotype  (Fowler  Environmental  tension  parameters such as  and latitude  1970, McGlade  a l l contribute to  1981), and occasionally  character differences are even traceable to the parental environment and  Lindsey  1978).  Until recently, morphological  (Dentry  traits i n salmonids were  rarely examined for their adaptive significance, although  the adaptiveness of  body morphology and f i n size has been i n f e r r e d i n Atlantic (Salmo salar) and coho salmon (Oncorhynchus kisutch) McPhail 1985a and 1985b).  (Riddell and Leggett  1981, Taylor and  3  Intuitively,  physiological  and  behavioural characters  should  be  closely  associated with the fitness of individuals and therefore should be particularly important  to  the  management  functional  (Ihssen  controlled  et  conditions,  application  al. 1981). the  of  the  Unless  genetic  and  stock  they  concept  are  environmental  different  are  unfertilized  gametes,  stocks and innate.  then  any  thus any observed  identical  sodium  latipes)  efflux  (Kado  et  and  Momo  al. 1977).  If, however,  starting  are  with  common  to  the both  differences in phenotype can be inferred to be has  been used  to examine  genetically  salt-water populations of medaka  1971),  temperature  (Morone americana) (Hall et al. 1978) (Refstie  effects  to  behavioural differences in fish in characters such  in fresh  and  conditions,  environmental  This experimental procedure  controlled physiological and as  under  under  contributions  behavioural phenotypes are often confounded. raised  fisheries  investigated  physiological and stocks  to  In  and  particular,  preference  in  (Qryzias  white  perch  age at smolting in Atlantic salmon this  method  has  proven  useful in  untangling stock specific migratory behaviour in sockeye salmon (Qncorhychus nerka),  rainbow  (Brannon  1967,  trout  (Salmo  Raleigh 1967,  gairdneri) Raleigh and  and  cutthroat trout  Chapman 1971,  (S.  clarki)  Kelso et al. 1981,  Northcote 1981).  Stock differences in coho salmon (O. kisutch) have been investigated using electrophoresis (May Wehrhahn  and  1975,  Powell  Allendorf and Utter 1979,  1987),  morphometric  and  Hjort and  meristic  Schreck  1982,  (Taylor  and  1987).  Of these studies, Taylor and McPhail (1985a and  and  McPhail  Schreck  data  Taylor and McPhail 1985a, Taylor 1986), swimming McPhail  1985b) and  (1987) attempted  agonistic  to look  behaviour  at the  (Rosenau  functional  1982,  (Hjort  and  performance and  McPhail  1985b) and  Rosenau  importance  of  the  4  characters studied and thus were able to comment on the adaptive significance of  these  characters.  differences  Taylor  and  McPhail  (1985a  and  1985b)  suggested  in morphology and swimming performance in juvenile coho were a  consequence  of the distance between spawning grounds and the sea.  and McPhail  (1987) postulated  differences  in agonistic  to either the presence of different  predator  habitat  Associated  space  characters,  and  productivity.  Rosenau  behaviour were related  species or differences physiological  and  in rearing behavioural  which may be equally important aspects of life history,  been studied. characteristics  have not  This thesis attempts to examine physiological and behavioural that  may  be  adaptive in the juvenile  life  history  phases of  spatially segregated stocks of coho salmon.  PHYSIOLOGICAL AND BEHAVIOURAL C H A R A C T E R I S T I C S STUDIED  A  literature  characteristics the  time  of  review  that  are  indicated  of  downstream  smolt  different  formation,  if  physiological  and  behavioural  primary importance to juvenile coho. migration  Inter population differences of  two  and  the  process  in migratory characteristics inherited,  could  reflect  of  smolt  These  are  formation.  and in the components  important  adaptations  to  environments.  Timing and direction of migration are the means whereby juvenile salmonids either reach nursery areas Raleigh  and  successfully Brannon between  Chapman  1971,  Brannon  1962 and 1981, 1972,  Kelso  Such  migratory  environment  and  activity  genome  of  Raleigh 1967 and  and  negotiate lake systems enroute to the sea  1982). the  (Northcote  Northcote  1971,  1981)  or  (Groot 1965, Quinn and  is  controlled  a  specific  by  stock  Brannon 1972, Kelso and Northcote 1981, Northcote 1981).  an  interaction  (Raleigh  1971,  5  Juvenile coho exhibit two  main periods of downstream movement and  periods have nocturnal peaks d u r i n g the first hours after dusk 1960,  Hoar 1976).  In the s p r i n g and summer immediately  (MacDonald  following emergence,  coho f r y are displaced downstream either as a result of increased velocities  (Hoar  1954)  Chapman 1965). cases two Scholz  or  Smith  and  1985).  1982,  and  Peterson  Mason  coho actively migrate downstream (Hasler Between these  two  (Gribanov  of  fall movements into overwintering habitat such as s p r i n g fed beaver ponds and  Elliot 1974, 1982,  Bustard  Peterson  and  and  riverine ponds (Skeesick  Narver 1975,  Reid 1984,  Cederholm and  Scarlett and  have evolved as a redistribution behaviour severe  This  u p r i v e r overwintering  behaviour  and  1948 cited by  1970,  Scarlett  Cederholm 1984).  Some of these latter movements are for extensive distances downstream, may  and  periods, coho exhibit both  downstream feeding migrations  t r i b u t a r i e s , sidechannels, Dinneford  1962,  current  From late A p r i l to early June of the following year, i n some  localized upstream and Smith 1985)  biological interactions (Chapman  years later, smolted  1983,  both  assures  conditions  increased  and  that acts to buffer the impact  (Cederholm and  s u r v i v a l by  Scarlett  1982).  dispersing interior coho into  accessible overwintering tributaries in the lower reaches of large Pacific coast r i v e r systems.  Smoltification is recognised as a dynamic process that transforms what have been freshwater animals into marine animals.  This process involves numerous  physiological,  changes  1980,  and  morphological  Wedemeyer et a l . 1980).  territorial  stream  streamlined and age  behavioural  resident  Through the smolting process,  parr  are  transformed  silvery migrant smolt (Hoar 1976).  of smoltification and  (Folmar and  into  the  Dickhoff  cryptic  and  gregarious,  Genetic variation i n the  i n the relative sequence of component changes  has  6  been demonstrated  in both Atlantic and  Pacific salmon  (Ricker  1972,  Refstie  et al. 1977).  Of the many changes that take place during the smoltification process, the increase in osmoregulatory ability that allows marine survival and growth is of prime importance. been  suggested  different  Variation in the osmoregulatory ability of coho smolts has  by  salmon  Wedemeyer et a l . (1980).  races  may  have  These  inherently  authors indicate that  different  smolt  levels  of  the  ATPase enzyme which is important in univalent ion regulation.  Seasonal  changes  that  reflect  juvenile coho development  ion  and  osmoregulatory  suggest a rapid  capacity  during  increase in capacity in the first  months following emergence (Conte et a l . 1966,  Otto 1971) with either limited  or  then a transition  no  reversion  during fall and  capabilities  the  following  Blackburn  1978,  Scholz  increase  in  1980,  development  et a l . 1981).  (Zaugg  Folmar  capacity,  is thought  Dickhoff 1980) after which further  spring  osmoregulatory  tolerance or survival,  winter, and  and as  to be  McLain  Dickhoff  indicated  an  are restrained  1972,  Clarke  1981).  by  The  increased  "acclimative" phase  survival in seawater may (Canagaratnam  and early  seawater  (Folmar  and  be high but growth and 1959,  Otto  1971,  Clarke  In situations where a reversion in osmoregulatory capacity has  been observed during winter, it may enzymes  and  to smolting  controlling  ion  regulation  be due (Giles  to a decrease in the activity of and  Vanstone  1976).  The  ion  regulatory capabilities of coho smolts in the spring following emergence are a function of a preadaptive increase in hormonal activity and enzyme production (Hoar This  and  Bell  1950,  Baggerman  apparently prepares  the  1960,  juvenile  Dickhoff et a l . 1978, coho  Scholz  for the transition  to  1980).  seawater  7  (Zaugg  and McLain  1972, Giles and Vanstone  1976,  Folmar and Dickhoff  1979,  Hasler and Scholz 1983).  Of  the behavioural changes  salinity  preference often  associated with smolting in coho,  are  seen  as  during migration (Mclnerney 1964)  and  an  or  index  of migratory disposition  Mclnerney  1970).  an  important  changes in  orientation  mechanism  salinity preference has been used as capacity  (Baggerman  1960,  Otto  and  There is also evidence for genetic variation in the timing  of preference shifts, at least within a population.  Otto (1971) alluded to the  possibility of such genetic differences between presmolt and within one stream.  smolt emigrants  This observation might explain the apparent stage specific  differences in seawater tolerance.  The  development  correlated 1964,  and  up  Mclnerney 1957,  a  preference for hypertonic seawater  with the onset of seaward  Otto  salinities  of  Mclnerney  migration (Baggerman  1970).  to a concentration  Coho  subyearlings  slightly  Mclnerney  saline water, mechanism  Subsequently, estuaries,  appear  to  a  1970).  in  an  movement Thus,  offered a gradient of 0-13  to  of exposure  migration (Baggerman increasing  increasing into when  prefer  (Houston  1957,  (Houston  (1964) suggested that the development of  independent  during  exposure  results  consequently Mclnerney  Mclnerney  1964), whereas smolted coho prefer hypertonic seawater  Baggerman 1960).  orientation  1960,  corresponding to isotonicity  a preference for saline water is a biphasic process. for  in coho is  full coho  salinities,  Initially, a preference  to seawater, 1960, such  preference for seawater  Mclnerney as  (Mclnerney  salinities  1964,  and  ppt seawater, Otto and Mclnerney  1964).  encountered  higher  f r y in December  acts as an  Otto  January  in and and  were  (1970) observed  8  a  shift  in preference  from 4-5  ppt  included in the gradient (4-19 January  but shifted to 13-14  to 6-7  ppt.  When freshwater  ppt), preferences ranged from 4-8  ppt in January and  in juvenile coho salmon.  response followed British were  and  salinity  in wild and  These are  preference.  laboratory raised  for  differences in the  their  similarity  distance from  in  the  severity of overwintering habitat.  changes  coho from  Columbia streams to document any chosen  osmoregulatory  Seasonal  (Taylor and  three  was  traits  conditions  to  differences. rates on  McPhail  monitored  determine  current  traits  were  interior  ontogenetic differences.  Streams  spawning  parameters  grounds to the  sea and  and the  At least the former parameter apparently  1985a and  genetic  swimming performance in  1985b). The reared  ontogeny of  these  under identical laboratory  contribution to  any  observed  stock  To examine possible effects of geographic variation in incubation  the ontogeny of the characters studied, the laboratory populations  were divide into  two  treatment  groups:  one  group  was  coastal temperature regime, while the other group was temperatures.  My  hypothesis  was  that  the  incubated incubated  physiological  characteristics mentioned above are adaptive and, observed  ability,  coastal and  physico-chemical  in populations  the  ppt before  behavioural  in these  both  contributes to adaptive variation in morphology and coho salmon  not  February.  This thesis investigates the ontogeny of three physiological and traits  was  and  under  a  at interior behavioural  therefore, any differences  between coastal and interior populations should be inherited.  9  S T U D Y  Two  streams,  (B.C.),  were  criteria  used  available  S T R E A M S  one in the interior  selected  British  Columbia  as sources for the experimental populations.  to select  previous  and one in coastal  these  streams  background  were  studies,  year-round  and  road  similarities  The  accessibility,  in the general  biophysical and chemical parameters of rearing habitat.  Interior streams were  arbitrarily  River  defined  as those  upstream  of the Fraser  canyon,  coastal streams were viewed as those draining the coastal mountains  while  into the  Strait of Georgia.  The  interior  stream was the Coldwater  River  (Figure 1) and the coastal  stream was Rosewall Creek on the east coast of Vancouver Island Hatchery  raised  Qualicum  River, were also used in the study.  15  km  southwest  transplanted 1980). available  juvenile  coho  of Rosewall  between  from  an alternative  Creek  Previously collected for all three  stream,  the  Big  The B i g Qualicum is located  (Figure  the two systems  coastal  (Figure 2).  2), and  (Bilton  coho  1978, Bilton  have  been  and Jenkinson  bio-reconnaissance data and survey reports are  drainage systems  (Smith  1969, Fraser  et al. 1974,  Wightman 1979, Whelen et al. 1983).  THE  COLDWATER  The Cascade  Coldwater Mountains  RIVER  River is part of the Fraser system and originates in the of southern B.C.  It first flows east and then north to  join the Nicola River near the town of Merritt  (Figure 1). The headwaters  flow through the interior Douglas fir biogeoclimatic zone but below  Kingsvale  10a  Figure 1.  The  Coldwater River study area.  Sampling was confined to the area upstream of the canyon located between the confluence with Brook Creek and Brodie. This map details access roads at the time of the study (1980-83).  10  11a  Figure 2.  The coastal streams study area.  Adult coho access is limited by fences associated with the hatcheries, and by a waterfall on Rosewall Creek and flow control facilities on the B i g Qualicum R i v e r .  11  124° 47"  COASTAL STUDY  N  KILOMETRES  AREA  I24°37'  STREAMS AREA  12  the stream is surrounded  by  the Ponderosa  the Thompson Plateau (Farley 1979). winter  temperatures,  lesser  relatively  fall) freshets  (Figure  low  3).  The  pine-bunchgrass zone typical of  Coldwater is characterized by cold  productivity  and  primarily  For much of its length,  aggrading, regularly meandering  spring  (with  the river  is an  watercourse with back and sidechannels and  other diverse habitat types (Wightman 1979).  Twelve including trout the  fish  coho and  and  trout  are  known  chinook  bull trout  salmon,  sculpins  species  salmon  from  Coldwater  (Oncorhynchus  and  char,  as  well as whitefish  suckers  (Catostomus  (Entosphenus tridentatus and/or Lampetra of Brodie (Figure  1).  The  River  tshawytscha),  (Salvelinus confluentus) (Table 1).  (Cottus cognatus),  upstream  the  drainage, steelhead  Of these species,  (Prosopium catostomus)  williamsoni), and  lamprey  spp.) ascend into the headwaters,  remaining species are confined  to the  lower river.  The River  Coldwater River supports the majority of coho spawners in the Nicola drainage, with  (Figure enter  1)  the area  (Kosakoski and  upstream  Hamilton  the lower river in October  begin.  Peak spawning  et a l . 1983).  and  1982,  of Brodie the most Whelen  Coho eggs then incubate for up  emerge in late May,  et a l . 1983).  migrate upstream  occurs in mid-November  June and early July.  heavily  used  Spawners  as the fall freshets  (Brown et al. 1979,  Whelen  to 7 months before the f r y  The prolonged incubation period is  a result of relatively low winter water temperatures (Table 2).  Coho rear throughout the Coldwater River, but are concentrated near the spawning  areas upstream  of Brodie (Kosakoski and  Hamilton  1982).  In this  13a  Figure 3.  Seasonal discharge trends for study streams.  Error bars represent 95% confidence limits. These discharge data are from W.S.C. stations in the Coldwater River (08LG048), Rosewall Creek (08HB037) and the Big Qualicum River (08HB001).  Study  Stream  Discharge  14  TABLE 1 FISH SPECIES COMPOSITION AND AVERAGE COHO ESCAPEMENT (1970-1982) AND SPAWNING TIMES FOR THE STUDY STREAMS. 3  Study Streams Parameter  Fish Specles coho salmon  Rosewa11 Creek  Big Qual|cum River  Coldwater River  X  X  X  X X  X X X  X  b  chlnook salmon chum salmon pink salmon kokanee/sockeye sa1mon steel head trout cutthroat trout  X X  X X  Dolly Varden char bul1 trout (char) mountain whlteflsh  ?  coastrange sculpln prickly sculpln  X X  ?  X  X  si I my sculpin threesplne stickleback redslde shiner longnose dace leopard dace flnescale sucker lamprey Average Coho Escapement (1970-1982) Coho Spawning Times Arrival Start Peak End  X  X ? X X ?  X X  X  X  X X X X X  348 ± 105.0 (n=12 y r . )  30,362 ± 7,690.6 (n=13 y r . )  494 ± 137.5 (n=13 y r . )  mid-October 1 ate October mid- to late Nov. December  September October  October late October  late November December  early to mid-Nov. late November  X - Species reported. ? - Species reported but questionable, or not reported but expected. - Data sources - Lister and Walker 1966, Brown et a l . 1977, Wlghtman 1979, Brown et a l . 1979, and Hancock et a l . 1985. k - S c i e n t i f i c names are given In Appendix 1.  a  15  TABLE  2  PHYSICAL AND CHEMICAL DATA FROM THE STUDY STREAMS.  Study Streams Parameter Rosewa11 Creek Longltude Latitude  Big QualIcum River  124° 47' W 49" 27' N  c  0  124° 37' W 49° 24' N  Coldwater River 121° 01' W 49° 42' N  Distance from the spawning grounds to the sea (km)  <4  <10  3.8  9.6  94  14.5  18.0  12.0  45.3  150.2  914.3  420  c  Accessible stream length (km) a  Average width (m)  a  Drainage area (km ) 2  9  Pool:Rlffles:Run area ratio* 3  Average gradient  (%) , a  c  Lower-0.03:0.05:0.92 Upper- 0.2:0.3:0.5  0.11:0.24:0.65  0.22:0.26:0.52  1.0 - 1.6  0.5 - 0 . 7  0.5 - 1.0  C  1,317.2 ± 219.9  Mean annual precipitation (mm) (1951-1980)  223.4 ± 13.0 (n=11)  Mean annual discharge (xlO dam ) (1964-1984)  82.6 ± 5.79 (n=6)  Dally water temperature (1980-1982) C C ) , Mean Max 1 mum MlnImum  (1982)° (n=317) 6.39 ± 0.209 16.5 0.0  3  c  b  c  Estimated Coho Incubation temperature ( ° C ) , b  pH r a n g e , b  c  c  Conductivity (umho/cm 8 2 5 ° C ) ,  c  (1980-1981) (n=353) 4.69 ± 0.220 17.5 0.0  2.7 ± 0 . 1 7 ° (n=241)  c  c  6.8 ± 0 . 1 8 (n=212)  6.7 - 7.93  b  7.4 - 7.8  (n=6)  b  216.6 ± 15.15 (n= 17)  (1982) (n=356) 8.85 ± 0.175 15.5 2.4  4.6 ± 0 . 1 3 (n=212)  44.7 ± 2 . 8 2 b  a  307.5 ± 74.3 (n=12)  (n=16)  c  3  C  c  C  76.2 + 1.20 (n=23)  c  b  6.5 - 7.68  b  48.9 ± 4 . 1 4 (n=16)  b  - Data sources - Fraser et al . 1974, Mundle and Mounce 1978, Wightman 1979, Brown et a l . 1979 and Hancock et a l . 1985. - Data source - F i e l d data c o l l e c t i o n s . - Data source - Survey and Maps Branch, Department of Energy, Mines and Resources; Department of Fisheries and Oceans; and Water Survey of Canada.  16  area, juveniles live amongst cover along the stream margin and the periphery of pools (Wightman 1979), as well as in sidechannels, accessible beaver dams and off-channel pools (Rosenau et al. 1986, Swales et al. 1986). and  beaver  dams appear  (Swales et a l . 1986).  to be  the most  Sidechannels  important overwintering habitats  Based on scales, most Coldwater coho juveniles appear  to spend one year in freshwater.  Seventy to 90% of returning adults are age  32*,  4 3 (Kalnin  and  the  remainder  are age  1982  cited  by  Kosakoski  and  Hamilton 1982, Whelen et al. 1983).  ROSEWALL CREEK  Rosewall Creek drains the Vancouver Mud  Bay  Coastal bounded  on  Baynes Sound  Douglas by  aggrading,  (Figure 2).  fir biogeoclimatic  valley  and  irregular  located about 3.8 km  canyon  pattern  accessibility is limited by  Island Beaufort Range northeast into Most of the watercourse lies in the  zone slopes  followed  (Farley over on  1979).  much  the  Rosewall Creek is  of its course, with  lower  coastal  plain.  an Fish  an impassable fall near the entrance to a canyon,  upstream of the mouth (Hancock  and Marshall 1985).  A  repetitive pool-riffle regime is found above the plain, while several long runs and  sidechannels are incorporated  Winter  floods  (Figure  3)  into  commonly  the stream result  in  character gravel  on  the  plain.  displacement  and  redistribution in the lower reaches.  Nine (Table  fish 1).  species Most  were  captured  of these were  in  the  numerous,  system but  only  during  field  a single  studies  stickleback  * The Gilbert-Rich system of age designation is used in this thesis (Koo 1962). Age 32 indicates a fish returning to spawn in its fourth year that migrated to sea in its second year.  17  (Gasterosteus aculeatus) and may  one  chinook  smolt were captured.  have strayed into the lower river from Baynes Sound.  spawned  throughout  the  accessible  (Qncorhynchus keta) were limited fish  fence was  installed in 1968  (Hancock and the  lower  Marshall 1985).  0.75  km  of the  portion  of  to the lower  the  1-2  The  latter  Historically, coho  creek,  kilometres.  while An  chum electric  as part of experimental hatchery operations The  fence has restricted most fish species to  stream.  Rainbow  and  possibly  however, still manage to migrate upstream of the fence and  cutthroat trout, coho are annually  lifted over by hatchery personnel.  Coho  spawners  begin  to  move  into  Rosewall  Creek  in  mid-October.  Spawning peaks in late November, although ripe spawners are present earlier in  the month.  and  Coho incubate until early spring, emerging as early as March  early A p r i l .  the first and  spring, but  along  during from  cutbanks  May  an  of the  2  THE  bordering second  32)  runs.  Seaward  spring of life.  program  to rear amongst- cover in pools  conducted  migration appears  to occur  Most of the returning spawners during  1972-77 were  (93.3-96.2%), with fewer numbers of two  (Bilton 1978,  3 years old  year old "jacks"  Bilton and Jenkinson 1980).  BIG QUALICUM RIVER  Coho from after  the majority appeared  experimental  (mostly aged (aged 2 )  Some newly emerged coho are displaced downstream during  rearing  the Big Qualicum problems  River Hatchery  eliminated one  groups (6°C incubation group).  of the  were included in the Rosewall  incubation  study  treatment  Biophysical and chemical characteristics, and  recognised coho life history patterns for the two streams are similar (Tables 1 and  2, Figure 3).  18  The  Big Qualicum  River drains the same mountain  zones as Rosewall Creek. The and  then  of  An  impassable falls and  the lake outlet.  which  The  A  good  south of Qualicum  Bay  waterworks are located just downstream  lower river flows along a static, irregular course,  benefits from the flow control implemented  1966).  biogeoclimatic  river initially flows southeast into Home Lake  northeast into the Strait of Georgia, just  (Figure 2).  range and  portion  of  the  lower  river  in 1963  (Lister and  is comprised  of  Walker  runs  with  interspersed pool-riffle patterns.  All five species of northeast Pacific salmon have been recorded from the Big Qualicum  River,  and  trout,  cottids  (Cottus  asper  stickleback and lamprey are also present (Table 1). Hatchery  C£.  aleuticus),  Big Qualicum River  (built in 1968) actively enhances chinook, coho and chum salmon, as  well as steelhead trout during  The  and  1975-83  were  (Minaker aged  32  et a l . 1979). (an  average  Most of the returning  of 68.8%) with  the  coho  remainder  comprised of two year old jacks (30.6%) and 4 year old adults (<1%).  S T U D Y STREAM  The  study  parameters  adaptive streams.  streams  were  chosen  for similarities  in the physico-chemical  of rearing habitat, associated with major differences in migratory  distance and history  COMPARISON  overwintering habitat severity.  differences  exist  consequences  between  of major  coastal  and  environmental  This study postulates that life interior  coho  differences  populations as  between  resident  19  The and,  three streams studied are all located just north of the 49° N. latitude  thus, experience similar  photoperiod regimes.  Field  sampling during  this study indicated that both the Coldwater and Rosewall are softwatered and seasonally  vary  Qualicum and  from  slightly  River appears  Mounce 1978).  than Rosewall Creek (roughly  acidic  to slightly  to exhibit similar water  levels.  and  The Big  Although the Coldwater River drains a much larger area (approximately 20 times larger), the drier interior climate  1/4 of the total  Qualicum  in pH.  chemistry (Table 2, Mundie  coastal  precipitation)  difference in mean annual discharge (only about Big  alkaline  Coldwater  rivers  share  Despite different hydrographs  results  in a much smaller  2.6 times) (Table 2).  similar  mean  annual  The  discharge  (Figure 3), the streams are similar in  habitat parameters such as wetted width and pool:riffle:run ratios (Table 2).  Fish populations in the study streams differed with the coastal populations composed of different and fewer species than the Coldwater River population. Many of the species encountered similar.  In the Coldwater,  chinook,  steelhead trout,  in the main rearing areas, however, were  juvenile  coho  char, whitefish  rear  in association  and sculpins.  with juvenile  In Rosewall  Creek  and the Big Qualicum River, juvenile coho rear along with steelhead (rainbow) trout, sculpins and possibly cutthroat trout. rear  with  juvenile  chinook.  Peak  In the Big Qualicum,  coho spawning  coho also  times are common  to  all  study drainages and most of the spawning coho in each system are aged 32»  While  similar  encounter  in general rearing  dramatically  different  overwintering environments studied  parameters, migratory  and freshet timing.  coho in the study  distances,  severity  streams of the  The coastal coho populations  rear within 4-10 km of the sea and can delay emigration until they  20  are prepared hand, was may  for seawater.  approximately  The  400  Coldwater  km  result in early emigrations.  River study  area, on  the other  from  the mouth of the Fraser River, which  The  Coldwater  River exhibits low flows and  freezing temperatures  during the winter months, which could affect not only  incubation  also overwintering survival.  least  rates but  a month  probably  more  earlier  than  productive  Coldwater winter  juveniles in the Coldwater-Nicola severity 1986),  of the  habitat by  sidechannels  (Swales  and  et a l . 1986). while  juveniles  Coastal coho emerge at  and  habitat in the  experience  main  watercourse.  overwintering in beaver  off-channel  pools  Freshet  flows occur  winter  freshets are  fed  by  ponds  groundwater  coho  encounter  the weaker fall floods during the first year of life.  emerge until  spring floods.  smoltification timing may, populations.  after  the  common  on  the  freshets and,  position in the streams during both Life  history  seepages  primarily in the spring in the  Coldwater  lower  Coho  (Rosenau et al.  River,  however, must maintain  and  system are believed to compensate for the  Coldwater  don't  warmer  characteristics  such  as  coast  any  therefore, only Coastal coho, the winter  and  migratory  and  as a result, vary between coastal and interior coho  21  METHODS  TERMINOLOGY  The terminology for juvenile life history stages used in this thesis generally follows that described by Allen and Ritter (1967). the  stream  resident  environment.  period, or that  time  prior  A juvenile coho refers to to transition  to a  Alevins are juveniles with the yolk sac still showing.  f r y refers to the pre-smolt but post-alevin period.  saline  The term  A smolt is a juvenile coho  which is usually one or two years of age and is physiologically prepared for transition to the sea.  Subyearling f r y are age 0+, while yearling juveniles  are aged 1+.  The  stocks used  in this study were from the Coldwater  stock), Rosewall Creek and Big Qualicum  River (an interior  River (coastal stocks).  Laboratory  reared groups of these stocks were incubated under two different  temperature  regimes and are referred to throughout the thesis as stock treatments.  The  terminology of current responses among fish was discussed by Arnold  (1974).  Rheotaxis  current.  The source of stimulation is along the long axis of the body which  is  then  oriented  refers  in line  to a  with  volitional,  the source.  directed  reaction  Positive  to a  water  rheotaxis involves  movement towards the source, whereas negative rheotaxis involves movement away  from  the source.  Fish  that  maintain  position  in the current while  oriented into the stimulus have been described as exhibiting positive rheotaxis (Keenleyside and Hoar  1954), but to allow a distinction between responses I  described this as a holding response.  Indirect reactions resulting in passive  movement downstream are described as displacement.  22  FIELD METHODS  Several items of equipment were used  consistently throughout the study.  In most cases, temperatures  were taken with a calibrated pocket thermometer  (to  a  the  nearest 0.5°C) or  0.1°C).  A  Fisher Model 119 pH  (accuracy  ±0.02  pH)  Radiometer-Copenhagen scale).  small digital meter was  and Type  thermister unit used  conductivity CDM2d  (to the nearest  to collect pH was  conductivity  measurements  measured  meter  with  (accuracy  a  ±2%  of  Dissolved oxygen levels were monitored with a YSI Model 51B oxygen  meter (accuracy ±0.2 mg.L~l).  Chemical and Physical Measurements  Most  chemical and  obtained and  from  survey reports  Marshall 1985)  Canada  (Anon.  drainage  physical  and  1982,  data  publications  precipitation  latitude, distance from the sea and 1:50,000 and  the various stream  (Wightman  Anon. 1985).  area, annual  from  1:250,000 scale maps.  1979,  of  the  systems  Brown et a l . 1979, Inland  Waters  Hancock  Directorate  Included were gradient, wetted and  annual  discharge.  were  of  width,  Longitude  and  accessible stream length were taken from Pool:riffle:run  ratios were measured in  the field with a tape measure.  During  each  field  trip,  several water  quality measurements were taken at  standard sites and included water temperature and sample was  From  pH.  In addition, a water  collected and later tested for conductivity at 25°C.  November  1980  fluctuations were monitored  until  November  1981,  in the Coldwater  daily  River and  water Chef  temperature Creek.  Chef  23  Creek is a small stream located less than a kilometre south of Rosewall Creek (Figure stock.  2)  and  was  originally  intended as the source of the coastal coho  Limited adult returns in 1981, however, necessitated turning attention  to Rosewall Creek.  Regular sampling with a pole seine for coho juveniles  was  conducted during 1980-81 in the Coldwater River and Chef Creek, and during 1981-82 in Rosewall Creek.  These  when emergence occurred and  how  samples  were used  to roughly establish  long relative incubation periods extended.  Incubation in the Coldwater appeared to occur from early November until midto  late June,  May.  while in the coastal streams incubation  ran from  November to  Mean incubation temperatures for coastal and interior streams were then  calculated used  using the 1980-81 temperature  in laboratory  temperature  incubation  data and  treatments.  data were obtained from  For  similar temperatures were purposes  Rosewall Creek  and  of  comparison,  the Big Qualicum  River for 1981-82.  Adult Coho Capture and Egg Handling  Adult coho were captured in the Coldwater River and Rosewall Creek during November  1981.  marquesette  Coho  spawners  were  collected  by  positioning  pole seine downstream of a likely looking holding area and  electroshocking the area downstream towards the net using a Smith-Root VII  electroshocker.  artificially stripped.  To  a  then Type  Ripe adults were held in portable pens until they were Sampling areas are shown in Figures 1 and 2.  maximize genetic variability within experimental groups, as many ripe  male and  female  spawners as  adult was  sexed, weighed  possible  were collected  to the nearest 0.05  (Appendix  2).  Each  kg with a spring balance and  24  measured to the nearest 0.5 cm with a tape measure (standard length). samples for later ageing were also collected  Spawners were stripped described  by Murray  Scale  (Appendix 2).  and the eggs fertilised  using the "dry method"  (1980) and Piper et a l . (1982).  Eggs and milt  from  several males and females were mixed in a clean d r y bucket, washed well with stream water and poured into a 2 L glass jar. and  The jar was filled with water  placed in the stream, out of direct light for at least two hours, to allow  water  hardening  of  the fertilized  eggs.  Jars  of  fertilized  eggs  were  transported to the lab in coolers filled with stream water.  Wild Coho F r y Capture and Handling  Starting in May of 1982, wild coho f r y were collected at two to three month intervals  from  Resident  juvenile  10 m  x 2 m  several coho  and 3 m  sites  in each  study  were  collected  with  x 1.5 m  marquesette  stream baited  Gee  measured  0.9 m  (Figure 4).  with a marquesette  mesh Fyke  net.  x 0.6 m and the bag was equipped  1  minnow  mesh pole seines.  traps were set overnight for periods of 16 to 20 hours. coho were sampled  (Figures  and  2).  traps  and  The minnow  Downstream migrant The Fyke  net mouth  with a floating live box  Catches were identified, counted and the coho placed in holding  pens until sampling was completed.  Juvenile coho were transported to the lab in 77 L garbage heavy to  (3 ml) plastic bags.  prevent predation.  inflated trip.  pails lined with  Coho were usually separated into size groupings  The bags were half filled with stream water and fish,  with oxygen, securely sealed, packed  with ice and covered for the  On arrival at the laboratory, the size groupings were checked and the  25a  Figure 4.  The Fyke net used for downstream sampling in the Coldwater River (Photo 1) and Rosewall Creek (Photo 2).  Photo 2 - The Coldwater River at Brodie.  26  juveniles were transferred to 65 L oval fiberglass tanks. of  approximately 5 L.min"-'- was  a  natural outdoor  mesh and  green  photoperiod.  netting,  and  pieces of b r i c k ) .  Tropical  Fish  maintained through  food  available live food  provided  The  and  Each  tank  with  was  An  exchange rate  the tanks, which received covered  submerged  with 2 cm  cover  (plastic  stretch cylinders  wild fish were fed an equal mixture of Tetramin  Clarke's New  Age  Trout  food  twice  a  day,  and  (gammarids, tubifex, mealworms, earthworms etc.) once a  day while the experimental tests were being  conducted.  EXPERIMENTAL GROUP MAINTENANCE  Temperature, monitored  with  intensities  pH, the  over  conductivity  and  same equipment  rearing  and  dissolved  mentioned  experimental  oxygen  under  equipment  measurements were  Field  Methods.  were measured  Light with  a  Li-Cor LI-185A Quantum/Radiometer photometer (accuracy 1% of full scale).  Incubation and Emergence  Incubation was by  Murray  incubated  carried  (1980). at  2°C  out in temperature  About  controlled incubators described  half of the eggs of each  (approximating  interior  stream  study population were  conditions) and  at  6°C  used  by  (representing coastal conditions).  The Murray  egg  containers used  (1980).  (6.3-9.5 mm  Eggs  were  during incubation differed placed  on  a  bed  diameter) in an aquarium filter  down over the eggs and through the gravel. prevent the alevins from burying themselves.  of  box The  1-2  from cm  those of  "pea  gravel"  that served to drawn water gravel was  small enough to  27  Since the eggs are particularly sensitive during the first 20 to 30 days of incubation or until after blastopore closure (C.B. Murray pers. comm.), they were not handled during this period except to remove dead eggs that started to  develop fungal problems.  fungus  infected  Individual egg stream.  eggs  volumes  These  were  After  blastopore closure, dead,  removed  every  were determined  incubation survival rates are listed in Appendix  data provided by Murray actual emergence was box" technique. 12 L aquarium  using  until  emergence.  of 30 eggs  incubation  from each  temperatures  and  3.  a graphic technique devised  from  As predicted emergence dates approached,  quantified using a modification of Mason's (1976) "choice  Several incubation boxes containing alevins were placed in a covered with black  The aquarium was apparatus was  (1980).  days  for a sample  data together with laboratory  Emergence times were predicted  few  coagulated or  plastic and  filled  with incubation  water.  covered with a weighted black plexiglass lid and the whole  submerged in a larger aerated tank of the same water.  After  a period of 30 minutes, the lid was slid back 1 cm and alevins were allowed to escape into the surrounding tank for 40 minutes.  Three  to six replicates  were tested for each experimental group and, if an average of more than 20% of was  the fish exhibited a photopositive response and escaped, the entire group deemed  transferred  to have emerged to  rearing  (Appendix  troughs  and  4).  left  for  Boxes of emerged 24  hours  to  f r y were  complete  the  emergence process.  Rearing of Experimental F r y  Laboratory  incubated groups  rearing troughs.  initially  were  reared  in 95  L  rectangular  Once the coho f r y reached 1.0 to 1.5 g in weight, at about  28  3 months, they were transferred were  reared for the remainder  to oval 750  L  of the study.  plexiglass Rearing  tanks where they  densities were kept  comparable between populations (Appendix 5).  The  various  dechlorinated directional Water was  rearing  water.  containers were In  current was  both  types  established  by  of  with  rearing  constantly  containers, a  the orientation  flowing constant  of the water  inlets.  fed into the bottom of the head of each trough, and into the larger  tanks at several depths down one side. were manipulated water was fry  supplied  During rearing, exchange flow rates  to maintain acceptable dissolved  supplied  to each  rearing  grew, the exchange rate was  oxygen  levels.  Initially,  trough at a rate of 3 L . m i n .  As  -1  raised to 5 L . m i n .  The  -1  the  larger plexiglass  tanks initially were supplied at a rate of 5 to 6 L.min -'-, but as the fish grew -  this was  raised  thus lower  to 8 to 10 L . m i n . -1  dissolved  During periods of high temperature  oxygen in late September and  October  and  (1982), the flow  rates were increased to 10 to 12 L . m i n . -1  Rearing temperatures were not manipulated; thus they fluctuated seasonally and  represented  monitored  only  coastal  daily at a set time  rearing  temperatures.  (12:00 hours).  Temperature  Water temperature  4.0°C on January 4, 1983 to 14.8°C on September 12, 1982  Dissolved oxygen levels, pH, until  July  (Appendix  1982 5).  Hach Model NI-8  and  then  (Figure 5).  a  month  for the  duration of  the  study  Total ammonia nitrogen ( N H 3 - N ) levels were measured with a kit (to the nearest 0.05  mg.L-1 t 8.2°C a  from  total ammonia and flow were monitored weekly  twice  levels during the study ranged 11.4  ranged  was  (96.8%  mg  NH.3-N.L~ ).  from 6.2 m g . L  1  -1  Dissolved oxygen  at 14.4°C (61% saturation) to  saturation), while pH  ranged  from  6.0  to  7.0.  29a  Figure 5.  Seasonal temperature changes i n the laboratory and study streams.  29  Laboratory  — i — i — i — i — i — i — i — i  Jan  Apr  i  Jul  i  i  O • X- • —A—  — i — i — i — i  Jan  Apr  i  Oct Date  Study  Temperatures  i  i  i  Jan  i  '  '  Apr  i  i  Jul  i — i — i — i  Oct Date  '  »  t  i  L  Oct  (1982-83)  Stream  i  i  Jul  Temperatures  R o s e w a l l Creek B i g Qualicum Ft. Coldwater Riven  i  i  i  t  i  Jan  i  i  i  Apr  (1981-82)  i  i  i  Jul  i  i  i  Oct  30  Total ammonia  nitrogen levels were rarely above 0.05 mg.L , which was the -1  lowest readable level of the kit, but on several occasions ammonia rise  as  high  thorough  as  0.25  mg.L~l.  Such  cleaning of the problem  0.45 mg N H 3 - N . I T  increases resulted  container.  Buckley  in an  levels did immediate  (1978) listed levels of  as toxic.  1  Observable problems with incoming rearing water were also monitored. only  problems recorded  we're suspensions  1982 and on October 2, 1982 and January  of silt during December  The  5 to 19,  1 to 3, 1983.  Following emergence, f r y were fed on ground Tetramin Tropical Fish food every  half hour to hour during daylight for the first  remainder Trout  of the first  food and Tetramin  feeders. the  two weeks, an mixture was  dispensed  few days.  of ground  Over the  Clarke's New  Age  6 to 8 times a day using automatic  Finally, the coho were fed 2 to 3 times daily on Trout food, with  pellet  size  roughly  Feeding  was  through  food rationing.  following  to satiation  and  the Oregon  no attempt  was  Except when ammonia  Moist  Pellet  feeding chart.  made to control  growth  rate  levels were high, tanks were  cleaned weekly and troughs every few days.  All laboratory reared f r y were exposed to a natural photoperiod, calculated for  50° N  latitude.  A  system  of timers, an automatic  dimmer  switch, and  frosted incandescent (25 W) and fluorescent (40 W) lights were arranged (one set  per trough  intensity  or  tank)  to approximate  dawn  and  dusk  and timing, as well as a natural photoperiod.  shifts  in light  The inclusion of a  dawn-dusk dimmer system was deemed necessary after observing that coho f r y are  stressed  by  a  rapid  shift  between  darkness  and  full  illumination.  31  The  automatic  feeders were connected  to the fluorescent light timer so that  feedings occurred only during full illumination.  An  interruption  treatment mortality  of  in the  Rosewall  (>95%).  To  water  Creek  flow  fish  on  September  incubated  at 6°C  10,  1982  resulted  Since  the  stock  in substantial  allow the experiments to continue, approximately  coho f r y were obtained from the Big Qualicum River Hatchery 1982.  to the  two  systems  share  1,000  on October 28,  biophysical features, and  since Big  Qualicum coho were transplanted to Rosewall Creek during experiments in the 1970's (Bilton  1978,  Bilton and  Jenkinson  1980), the genetic makeup and  life  histories of the two stocks were presumed to be similar.  WEIGHT AND  L E N G T H MEASUREMENTS, AND  Starting one month after emergence, and thereafter, measured  a sample of f r y from  for weight and  length.  each Ten  AGEING PROCEDURES  at approximately monthly intervals  stock  and  incubation treatment  f r y from each experimental  were measured, for a total of 80 f r y per a stock treatment.  was  replicate  Wild f r y brought  back to the laboratory were also measured within a day or two of capture.  Coho  were  anaesthetised  moist to the nearest 0.01 to  the  nearest  0.5  length  in the  study,  length,  and  mm  conversion  with  2-phenoxyethanol  (0.25  mLL  - 1  ),  weighed  g on a Sartorius Model 1219MP balance and measured on  a smolt  samples  board.  were  equations  While lengths are given as fork  also measured  are  given  for standard  in Appendix  definitions given by Ricker and Meerman (1945) were used.  6.  and The  total length  32  Coho scale samples were aged by microscope  slides  and  microscope or  a Leitz  acrylic  and  sheets  Fisheries and  Significant treatments  reading  fixing the separated  them  scale reader.  read  using  an  with Adult  overhead  a  Nikon  coho  scales between binocular  two  compound  scales were imprinted  projector at the  on  Department of  Oceans.  differences  in  size  were  tested  for  between  to examine the potential for size effects on  behavioural responses studied.  stocks  and  the physiological and  Comparisons also were made to see if migrant  f r y differed in size significantly from resident f r y .  EXPERIMENTAL TECHNIQUES  Three  juvenile life  environmental  current  traits  which  differences were monitored  on each stock and samples.  history  incubation treatment,  might  vary  at approximately  in  response  to  monthly intervals  and at 2 to 3 month intervals on wild  Life history characters included plasma sodium regulatory ability, response  and  salinity  preference.  Laboratory  raised  groups  were  monitored beginning one month after emergence.  Plasma Sodium Regulatory  The  Ability  osmoregulatory ability of coho juveniles was  challenge test described initially by measures the  Clarke and  tested using the seawater  Blackburn  (1977).  test  ability of coho to regulate the concentration of sodium in the  blood plasma after 24 hours in seawater (salinity of 29 to 30 ppt). was  The  This test  chosen over survival, or tolerance of seawater, because coho are capable  33  of entering seawater some 6 to 7 months before actual migration to the sea (Conte et a l . 1966), even activity  and  growth  concentration  is a  though  physiological stress will limit subsequent  (Canagaratnam  good  index  of  1959,  Otto  1971).  osmoregulatory ability  Plasma  sodium  because  sodium  chloride (NaCl) is a major osmotic component in extracellular fluid (Clarke and Blackburn the  1977).  sensitivity  important  The  relative simplicity of the methodology,  of sodium  ion measurement  advantages in selecting  using  this method.  combined  with  a flame photometer,  were  Handling techniques were,  however, modified to meet the requirements of the study.  Test  containers consisted  with a 3 ml plastic bag. rearing  water  Water in these containers was  temperatures  through cooling coils wrapped bag. bags. pH  Each container was  of 90 L rectangular plastic garbage pails lined  by  running  freshwater  kept to within 1°C of  from  the  same source  between the walls of the container and the liner  divided into 9 equal sections by  suspended  mesh  Suitable dissolved oxygen levels were maintained with air stones, and  and dissolved oxygen were regularly monitored.  Dissolved oxygen levels  were kept above 90% saturation, while the pH in seawater was around 7.5 and in  freshwater  conducted  was  under  comparable  dawn-dusk  to  and  rearing  pH  levels.  photoperiod  Experiments  conditions  identical  were  to those  experienced by rearing groups.  For each test, 20 fish were exposed for 24 hours to 29 to 30 ppt seawater while  10 control  fish  were placed  in freshwater  for the same time period.  Seawater challenge tests usually started around mid-afternoon (14:00 to 17:00 hours)  and  measured dipnetting  plasma  samples  were  collected  the  for sodium content the following day. each  fish  out of the rearing  following  afternoon  Each test began  tank, drying  by  it with a soft  and  gently damp  34  cloth, placing the fish in a preweighed container of water and weight  difference.  The  fish  were then  placed  recording the  into the mesh  baskets  and  suspended in either seawater or freshwater.  After  24  hours,  the  fish  were  anaesthetized  in 2-phenoxyethanol,  for  blood  a  caudal  Photometer was of plasma. Blackburn  sample  sodium  those  and  which of  Blackburn  mesh  measured  and  1977).  An  baskets, sacrificed  IL443 Flame  followed those outlined by Clarke and  that the  an extra factor of two  passed  data  were  plasma  by  several criteria  used  (1:400) (see section on  healthy and, swimming  differed  by  were  in subsequent  aliquots were  concentrations  except  Experiments).  to be robust and  replicates sodium  fish  levels  fish  again,  in their  the photometer operating manual (Anon. 1977),  Calibration of  those  required  (Clarke and  Plasma handling procedures  that samples were diluted  Only  weighed  still  used to measure the sodium concentration in 2 or 5 ul aliquots  (1977) and  Design and  removed,  sampled  analyses.  for  Test  plasma  fish  were  following 24 hours in seawater, only  normally  were  collected  for each  more  than  5  sampled. fish  mM.L~l,  In  addition,  and, the  if aliquot data  were  eliminated.  Mean sodium levels for seawater challenged over  time  to  Developmental populations then  demonstrate patterns  the  development  were compared  stock variation.  between  populations  of  control fish were plotted osmoregulatory  between incubation treatments  to determine incubation effects on  compared  and  ability. within  plasma sodium regulation, and  within incubation  treatments  to examine  35  Current Response  The  current  examined Kelso  response  of different  using a modification  and Northcote  coho  populations and  of the response  channel  groups  design outlined  was by  (Kelso 1972, Kelso et a l . 1981, Northcote and Kelso  1981).  The  channels  described 0.22 m  used  by Rosenau  in this  study  were built  from  oval stream  (1984), and had a circumference of 5 m,  and a volume of 0.26 m^  (260 L) (Figure  6).  Each  divided into 22 chambers with an individual volume of 0.012  channels  a depth of channel was  (12 L ) .  One end of each channel was closed with a fiberglass resin coated plywood barrier. on  Water was fed into the channel from a central area through a tube  one side of the barrier.  first,  This set up a flow around  both  to prevent  fish  from  partially diffused the inflow current. plywood  water  reaching the inlet  with a 2.5 cm hole positioned  level.  side  "pools" provided  and also to  at least 2 cm  below the channel  Water drained back into the central area through a submerged  to side  down  the channel  mesh  gates,  which  The partition holes were staggered  to produce  (chambers) separated by "riffles" with  tube  Each of the successive partitions were  screen in the last downstream chamber. from  The  or inlet chamber, was separated from the second chamber by a screen  partition  of  the channel.  could  a series  (holes). be  through 10 chambers upstream or downstream.  raised  of 21 accessible  A release chamber to allow  fish  was  to move  36a  Figure 6.  Current response channel design.  37  Three  channels, stacked one  on top of the other, on an aluminium rack  were used in the current response experiments.  rack was  enclosed in a  darkroom  built of Dexion angle iron, plywood and black plastic.  Each channel  received  illumination  incandescent lights. by  an  from  two  40  W  The  flourescent  lights  and  60  W  The intensity of the incandescent lights was  external dimmer switch.  from outside the chamber.  The  frosted  controlled  fluorescent lights were also controlled  Light intensities at the center of each of the 21  chambers comprising each of the three channels averaged  11.5 * 0.41 lux,  11.9 ± 0.43 lux and 11.5 ± 0.35 l u x .  The  starters  for fluorescent  importance of magnetic  lights  orientation  produce  during  a  seaward  magnetic  To  magnetic 15T)  was  chamber. channels  check  if the starters  orientation used No was  might  cause  deviation  the  orientation  from  observed.  Coho  the  at  a localized  the  longitudinal  moving  the  1982, Quinn and Groot  of the channel apparatus, a field  to check  and  migration of sockeye and  chum salmon has been documented (Quinn and Brannon 1983).  field  compass  top  and  NE-SW  upstream  deviation  and  in the  (Silva  bottom  Type  of each  orientation  of  downstream  the  in the  channels would, therefore, move in the same general easterly direction.  A  single gravity feed holding tank provided  with a De  unit fed water into the central area in each channel.  Laval milk cooler  Submerged Little Giant  Model 3E-12NDVR pumps then fed water into each inlet chamber. the  Water from  gravity feed source to each channel was controlled by a valve which could  be adjusted to vary the water flow and subsequently the temperature in each channel.  An overflow pipe provided a drain for excess water.  rate in each tank varied each  channel  was  between 3 and  kept  to  within  5 L.min , -1  1°C  of  and  The  exchange  the temperature of  rearing  temperatures.  38  Dissolved  oxygen  levels  were occasionally  checked  at the most  downstream  chamber and were routinely greater than 95% saturation.  A  second  valve between each  adjust the flow rate. at  each  riffle  and were  channel was determined  (40.1  critical cm.s )  monitored  rheotactic threshold movements product  of  conditions,  (Appendix  and  tube was used to  Nixon  Instrumentation  Limited  The velocity used was less than the  for coho  f r y (16 cm.s )  and  -1  1977),  but was  greater  smolts  than the  (0.4 cm.s ) (Gregory and Fields 1962).  Any  -1  should  displacement.  the channels  a  -1  basis, a full flow regime along each  Mclnerney  therefore,  current  7).  speeds  for coho  observed,  with  On a monthly  swimming (Glova  -1  and channel inlet  Current velocities were set at approximately 10 cm.s  Streamflo meter T y p e 403.  minimal  pump  have  Finally,  been to  responsive and not a better  simulate  were provided with a substrate of sand  stream and pea  gravel to a depth of 2 cm.  The et  test  procedure  a l . (1981).  illumination Kelso  (Hoar  for laboratory  Because  current  responses  are strongly  et a l . 1981),  tests  were  run under  Prior to each  flow levels were noted at the riffles release chamber.  both  light  affected  (diurnal)  test, temperatures  immediately upstream  by  and  dark  were checked and and downstream of  Adjustments were made if necessary.  Samples of 20 juvenile coho were used in each test. in  of Kelso  1958, Northcote 1962, Hartman et al. 1967, Brannon 1972,  (nocturnal) conditions.  the  reared stocks followed that  Test fish were isolated  the central release chamber of each channel by closing the screen gates.  Diurnal tests intensity  began with a 30 minute  acclimation period in the dark.  of the incandescent lights was increased  over a 30 minute  The  period,  39  after the  which  the  test had  fluorescent  begun, the  test started,  the  lights were switched  gates were raised.  fluorescent  Two  Fifteen  and  minutes after  a half hours after  the  distribution of the  test fish recorded.  central chamber gates were then closed, the fish returned to the  chamber  and  a  nocturnal  acclimation period  test  with  the  minutes.  diurnal  Two  and  the  test,  the  given  sample  nocturnal tests.  Nocturnal tests  of  20  the  release  began  with  fluorescent  an  lights  incandescent lights dimmed over 30 minutes. release  chamber  a half hours into the  raised to half intensity and  A  conducted.  (30 minutes) under full illumination,  were then extinguished and As  the  lights were extinguished, the incandescent lights  were dimmed to half intensity and The  on.  gates were  test, the  raised  after  15  incandescent lights were  the distribution of the fish recorded.  coho  In all, 12  was  used  replicates  for  only  one  set  of  diurnal  and  of each incubation treatment for each  stock were conducted monthly using a total of 240  fry.  Test coho were kept  separate from the rearing stock until each month's testing was  completed.  Wild fish from each population were handled in a similar fashion, although the of  sample sizes varied each  stock  per  test  samples were used.  with the period  number of fish collected. were run.  When this was  Whenever  Only 6 replicates  possible,  six  separate  not possible, the fish were mixed together  after each test, left for at least 24  hours and  a new  sample taken.  Equal  sized samples were used during each test period.  A was was  "net  rank number" (NRN)  scoring  system described by Northcote (1981)  used to quantify the directional response of each sample. given  chambers  to +1  each to  +10  chamber, and  with  the  downstream  release chambers  chamber -1  to  A rank number zero,  -10  upstream  (Figure  6).  40  Following each test, the number of f r y in each chamber was NRN  score was  counted  and  the  calculated as: 10 i=-10 NRN  =  + 10 10 i=-10  where i = the chamber rank number and n^ = the number of fish in chamber i . The  constant of 10 was  more than less than  10 indicated 10 indicated  sample maintained  NRN  added to maintain positive scores.  on  average an  a downstream response.  and  effects  and  while a score of  A score of 10 indicated  the  dark conditions were plotted over time for each  stock to portray the ontogeny of current responses.  the seawater challenge data, the trends in NRN incubation  response,  position.  scores under light and  treatment  upstream  Thus a score of  treatments between  within stocks  stocks within  to  with  scores were compared between  determine  incubation  As  incubation  treatments  temperature  to examine  stock  variation.  Salinity Preference  Salinity preference was and  Spieler  series  of  discontiuous  1978). baffles  The  tested using a modified Staaland device modified Staaland  which  salinities  effectively  maintained  by  device is a channel  provide differential  a  horizontal  densities  (Fivizzani  divided by gradient  (Staaland  a of  1969).  41  The  device  grandis, (Spieler 0.18  m  6  has cm  been  used  in length,  et a l . 1976). wide, 0.5 m  Each  gradients.  The  plexiglass  (15 mm  (5 mm along  of  were  the  end  Fundulus  in the  gradient  in this study was  divided into 6 chambers  1.8  m  long,  (salinities) by  attached  longitudinally bottom  while the  to  provide  a  bank  11  baffles  thus  roughened  The  reduces  (Fivizzani and with  pulley operated plexiglass gate was  chamber in each channel.  test  were made of black plexiglass  to negotiate the channel surfaces were  of  of the channels were made of white  Colouring the baffles black orients exploration by  interior A  eight  m.  thick),  time required  reflection. one  used  of  instability  the longitudinal axis of the channel and  error" All  was  movements  significant  channel  sides, ends and  thick).  no  the  The baffles separating chambers and salinities were 0.3 m  deep and overlapped 0.15  channels  with  deep and  baffles (Figure 7).  Four  to monitor  steel  used  test  fish  the "trial  and  Spieler wool  to  1978). reduce  to allow isolation of  isolated chambers served as release  sites, and were alternated end to end from channel to channel to reverse the direction of the incremental salinity gradients.  This design served to lessen  the  such  effect  on  the  results  of  outside stimuli  as  variations  in light  intensity and magnetic field.  The  four chambers were submerged, up  to the gradient water level, in a  elongated fiberglass trough through which water from the same source as the rearing water was  passed to regulated gradient temperatures to within 1°C of  rearing temperatures. 4.65  mm  OD;  A line of silastic medical grade tubing (3.35 mm  Dow-Corning  catalogue  number  601-335) was  middle of each channel about 2 cm from the bottom. at both ends to an oxygen cylinder.  Oxygen was  run  Each tube was  down  ID x the  connected  fed into the tubes at about  42a  Figure 7  Salinity preference channel design.  42  SCHEMATIC  SIDE VIEW  OF A S I N G L E  WATER / LEVEL  CHANNEL  UPPER BAFFLE  \  0.3' m  GATE  SALINITY  GRADIENT TRANSITION • 0 3 m-  SILASTIC MEDICAL TUBING WITH HIGH OXYGEN PERMEABILITY  LOWER_ BAFFLE'  HIGH SALINITY  1.8 m  SCHEMATIC END VIEW  0.5 m  0.72 m-  ZZL  7  43  5.8  kg.cm"'' (100 psi) pressure, and  the length of each channel. number  of tests involving  oxygen  levels  ranged  diffused evenly into each chamber along  Dissolved oxygen levels were checked a variety  of different  from  7.6  mg.L  As  noted  by  (71-100% saturation).  -1  at  Otto  12°C and  sized  following a  test f r y .  to 11.1  rng.L"  Mclnerney  Dissolved at  1  11.2°C  (1970),  dissolved  oxygen gradients are unavoidable because of differences in oxygen  solubility  at different salinities.  Salinities seawater  were mixed  and  checking  density-salinity channel was  by  tables  volumetrically  the  resulting  (Jorgensen  combining solution  1979).  To  over the tops of the lower  added  shifts  in  salinity  baffles.  were  a  establish  and  ppt and  gradient,  each  a  then water of the lowest  Towards the end  sharp.  30  hydrometer  slowly until the water level was  water of the highest salinity in the gradient was ensure  with  filled with the appropriate salinity, and  salinity in the gradient was  freshwater  4-5  cm  of filling the channel,  added at the opposite end to  Salinity  gradients  were  usually  established the day before a test and allowed to stabilise in temperature.  Following  each  test,  selected channel was depths  (surface,  conductivity and measured throughout 1.5°C  The  at  the  maintenance  checked  6  cm,  by 12  of  the  withdrawing cm,  and  gradient in one  10-20  the  ml of water at four set  bottom),  determining the corresponding salinity.  the  same  the tests,  depth.  although  Salinity  gradients  temperatures  randomly  measuring  sample  Temperatures were  were  well  occasionally varied  maintained as much as  along a channel.  salinity  preference apparatus  was  surrounded  by  a plywood, black  plastic and angle iron enclosure extending approximately 2 m above the top of  44  the channels.  The  enclosure was  added illumination of two 1 m 5.5  centrally located 40 W  above the channels. ± 0.09  lux, 5.4  channels.  Because  (Baggerman  1960,  lux and  previous  both the morning and  and  5.4  studies  *• 0.15  noted  Mclnerney  provided with the  fluorescent lights positioned  Light intensities averaged  ± 0.14  Otto  open to natural light and  (n=12) 5.4 ± 0.09  lux along each of the four  no  diel  1970), tests  shifts  in  preference  were conducted  during  afternoon.  Distributions of f r y in the four channels were viewed through located at the top of the enclosure and The  lux,  two mirrors,  at about a 45° angle to the channels.  observer sat to one side of the enclosure and could watch fish movements  in each of the channels.  Salinity and  4 to  slightly  preferences 24  ppt.  saline  were tested in two  These  24  ppt  range  are  encountered  by  spring  early  and  gradients were chosen  solution, as might occur  shift salinity preferences below  (Otto and normal  coho migrating summer  the  (Waldichuk 1952,  ppt  ppt  4 to 24  controls  were  replicates  salinity  established in  of each  the  southern  area  separate, control  1981).  subtly  Salinities in the 20 to but  reflect  Strait  is affected  Thomson  ppt  acclimation to a  in estuarine conditions, can  gradients, and  gradient and  because  Mclnerney 1970).  into  when  gradients, 0 to 20  coastal salinities,  freshet discharge and  seawater  the  of Georgia  by  the  Fraser  range in late River  For each test, 0 to 20  freshwater  and  4 ppt  randomly  selected channels.  for each  stock  treatment  salinity  were  Four run  each month.  The  test procedure  chamber.  began by placing 5 juvenile coho in each closed release  Test f r y were left for an acclimation period of at least 30 minutes,  45  after which the gates were raised and for two  hours.  The  the f r y allowed to explore the channels  distribution of fish in each channel was  observed  minute intervals for four 20 minute periods over the next two  hours.  at one As  a  result, 400 observations were collected for each replicate.  Each channel, every  second  when viewed from above, had  section  sections represented  represented  gradient shifts.  the gradient shift sections was sections  a  pure  12 sections.  salinity  while  In a gradient, the  intervening  Since the vertical position of coho in  unknown, the number of observations in these  were divided proportionately between  the adjoining pure  This resulted in a distribution over six salinities.  salinities.  Control distributions were  treated in a similar manner.  Control and the  test replicate distributions were pooled and  distributions  frequency  were  not  significantly  different,  compared.  slight  deviations  peaks could unrealistically change modal preferences.  an  "end  Otto  and  Mclnerney  (Houston 1957, 1970).  distribution  was  subtracted  preferences  were  then  treatment, variation.  and  plotted  discussed  Previous  on" effect or a tendency for test fish to orient  towards the release chamber 1969,  in  Therefore,  when not different, the data were eliminated from further analyses. workers have noted  When  as  from  To the  against to  Hurley and  avoid  such  related time  incubation  a  test  for each treatment  Woodall 1968, problem,  the  distribution. stock  and  effects  Williams control Modal  incubation and  stock  46  S T A T I S T I C A L METHODS  Standard  parametric  and nonparametric techniques  available  in several software  thesis.  Data  method  sets were  transformed,  were  angular transformed  Comparisons  When  square  necessary,  root  test  throughout the using  graphic  (Minitab Release  continuous  transformed  a  and  5.1  data were login proportions  were  to improve normality and reduce variance.  between  t-tests or analyses  for normality  1981) or a Shapiro-Wilk  et al. 1985).  counts  packages were used  routinely checked  (Sokal and Rohlf  (MTB51); Ryan  statistical  (Sokal and Rohlf 1981)  normal  of variance  data  sets  (ANOVA)  were  conducted  (UBC GENLIN;  with  appropriate  Greig and Bjerring  1980) after equality of variance was tested using an F-max or Bartlett's test. Unplanned multiple comparisons of means were carried out using a T-method, Tukey-Kramer's  test  or  comparison, Dunnett's test  T'-test  (Sokal  and  Rohlf  (Steel and T o r r i e 1980).  1981) or  a  pairwise  When sample variances  were heteroscedastic, a t'-test or the Games and Howell method were used to approximately  test  for  Nonparametric  data  sets  (MTB51).  equality were  of  means  compared  (Sokal  using  and  Rohlf  the Mann-Whitney  1981). U  test  Unplanned multiple comparison by nonparametric STP test was then  used to group data sets (Sokal and Rohlf 1981).  To  test for differences between growth trends  for wild and  groups, regression analyses were carried out on login transformed time  data.  Consecutively  numbered  days), were used as time units. analyses of covariance  days,  Regression  over  a two year  experimental weight and  period  (1-730  lines were then compared using  (ANCOVAR) (BMPD P-IV; Dixon 1981).  47  Salinity  preference  data  were  plotted  as  the  mode  of  net  gradient  distributions over time.  In general, preference data has been describe as the  mode  distribution  of  a  Mclnerney and  preference  1970).  (Hurley  and  Woodall  1968,  Otto  and  Prior to determining the net distribution, however, control  test distributions were compared with a Mann-Whitney U test and the data  omitted from  the plots if no significant difference was  observed.  Best fitted  lines were applied to the plots of modal preference points using "lowess", smoothing  program  in S  (Becker  were standardized at default  and  Chambers  which comprised  1984).  Program  the fraction  a  parameters  of data  smoothing each point f=2/3, the number of iterations iter=3, and  used in  the interval  size delta=l% of the range of x=log(time).  Tabulated the mean.  data are generally listed When plotted,  as a mean and  one  standard error of  data are shown as the mean with 95%  confidence  limits.  DESIGN AND  The  C A L I B R A T I O N OF  following tests and  of the experiments  and  Calibration  various  essential  to  conditions. and  of  the  the The  EXPERIMENTS  analyses were carried out to establish the design  particularly to calibrate the behavioural apparatus  interpretation  of  under  nonexperimental  responses  observed  experiments.  conditions  under  was  experimental  tests are discussed only briefly here; additional descriptions  full results are given in the appendices  (Appendix  8).  48  Plasma Sodium Regulatory Ability  Timing of Sample Collection  Clarke and Blackburn (1977 and 1978) observed that when plasma concentrations  approach  170 mM.L  -1  after  24 hours  in seawater,  sodium  coho are  capable of growing in salt water and have apparently physiologically smolted. Other workers,  however, have suggested migratory or smolted coho  require  30 hours to initiate osmoregulation (Conte et al. 1966) or 36 hours to adapt to seawater  (Miles and Smith 1968).  Presmolt coho, on the other hand, appear  to require 4 to 7 days of acclimation to develop an operational sodium  pump  (Folmar and Dickhoff 1979).  To reaffirm that a 24 hour sampling period was  acceptable  for  smolted  considering  the handling and confinement procedures used in this thesis, a  separating  and  non-smolted  coho,  particularly  time series of sampling was conducted on both coho f r y and smolts.  Plasma sodium levels for f r y and smolts appeared to peak after 6 to 8 hours in  seawater  hours  (Appendix 8, Figure  observed  reported groups,  by  by Folmar mean  hour periods adaptation  sodium  Clarke  1).  This is somewhat earlier than the 16  and Blackburn  and Dickhoff  (1981).  concentrations  were  (1977) or the 24 to 48 Within both not different  hours  the f r y and smolt between  24 and 48  (t-test, p > 0.05) (Appendix 8, Table 1). This indicates that  was  generally  complete.  Thus,  plasma  sodium  levels  measured  after 24 hours in seawater appear to be a good measure of the preacclimation osmoregulatory capacity of coho juveniles.  49  Dilution and Range Setting Effects on Photometric Readings  Under K  +  normal circumstances, the IL443 Flame Photometer uses a 140 Na /5 +  calibration  standard  (Anon. 1977). concentrations  diluted  1:200  in a 15 mEq  Li .L +  "blank." solution  - 1  Plasma samples receive the same dilution treatment and sodium are  read  directly  from  a digital  readout. This  photometer,  however, is a clinical instrument designed to measure sodium concentrations in human fluids. 180 mM  These fluids give measurements of 3.5 mM  Na .L~1 (urine) (Anon. 1977). +  to a 0 to 199.9 mM  Na .L +  often exceed 200 mM  - 1  range.  Na .L +  include  (saliva) to  Consequently, the machine is limited  Because, in coho, plasma sodium levels  Na .L~1, certain modifications in measurement techniques +  were necessary to reach the actual sodium concentration. could  - 1  changes  in  calibration  standard  and  Such modifications  sample  dilution  and  adjustment of the range settings on the photometer.  To examine how values measured  several alternative modifications affected the plasma sodium  by  the photometer, plasma samples from fish  and  salt water were divided  One  of these was  control.  2).  treatment.  four different treatments (Appendix 8).  equivalent to the recommended techniques and served as a  Plasma sodium values under the four treatments were not different  among fish Table  between  held in fresh  held  in fresh  Mean  sodium  or salt water values,  (ANOVA,  however,  p >>  were  0.05)  highest  (Appendix 8, in the  control  A treatment in which samples were diluted 1:400 and the resulting  readings increased by a factor of two was selected for use in this study.  50  Handling and Confinement Effects  For non-smolted coho exposed to seawater for 24 hours, mean plasma sodium levels in this study were generally higher than expected (Conte et al. 1966, Clarke  and  Blackburn  1978,  Clarke  et a l . 1981).  seawater challenge tests first were weighed the tests. expected  Perhaps this handling and plasma  sodium  levels  involved  in the  and confined in mesh bags during  confinement produced the higher than  through  osmotic imbalance (Schreck 1981).  Coho  a stress  induced hydromineral and  Pretest weighing, however, was  considered  necessary since hypertonic tissue water loss during saltwater adaptation can result in weight loss  (Miles and  Smith  1969).  Confinement  was  required to  allow later analysis of weight versus plasma sodium relationships.  To  test  received water. exposure  the effects of handling  three As  different  and  confinement, samples  treatments while exposed  to either  a control treatment, coho were not weighed  and  were  not  confined.  Two  of coho smolts fresh  prior to salt  other treatments involved  levels of handling and confinement (Appendix 8).  or  salt water  various  Care was taken to eliminate  fish size as a factor in plasma sodium values (Appendix 8, Table 3).  Handling and confinement produced significant differences between treatment sodium plasma means in both fresh (ANOVA,  p  <  0.01)  samples  (Games and Howell method) and salt water  (Appendix  8,  Table  highest, however, under the control treatment. this  test  do  not explain  compensate  for the effects  treatment 3;  Appendix  Confinement,  Recent  sodium  values were  levels observed  however, appeared  of pretest weighing  8, Table 3).  Mean  Consequently, the results of  the higher than expected  among seawater adapted coho.  3).  to partially  (treatment 2 compared  work suggests that  with  both test  51  container dimensions contribute These  to  same  and  raised  the time the fish are in anaesthetic following a test  plasma  sodium  conditions probably  sodium values observed pretest weighing  and  here.  levels  (Blackburn  contributed  to  the  and  higher  Clarke than  1987).  expected  Although plasma sodium levels were high with  confinement,  they were consistently high and  thus the  seasonal patterns examined in this study should not have been differentially affected.  Current Response  Timing of Distribution Collection  The  technique for measuring  Northcote  (1981) including  current response  their  schedule  starts collecting distributional data 2.5 current  response  studies  use  of observations.  hours  a variety  followed Kelso  1953,  Brannon  1967  and  Chapman  1971).  response  appeared  device.  Since the channels used  Kelso  In these  1972,  of periods (16-30 minutes  Raleigh the  time  1967 fish  to be partially dependent on  examine  observed  and  1971,  to 24-48 and and  to show  the design of the  a  response  from those used  by  the time of data collection  (Appendix 8).  such  over a 4.0  hours,  Other  Raleigh  effects, hour  movements  of  several  period under light and  samples  of  coho  dark conditions.  suggest that movement away from the central release chamber was 3.0  schedule  (McKinnon  were allowed  in this study differed  (1972), the effects of exploration time and  were investigated  To  studies,  This  after the test begins.  hours), often variable within a study, before data collection Hoar  (1972) and  but movement to the ends of the channels continued  The  were data  stable after throughout  52  the 4.0 fish  hour experimental period and  had  Since  explored  the  main  hours, 2.5  the channel  movement  out  probably would have continued until all  to its ends of  the  release chamber  values.  different dark  Under  over  light  and  the entire observation  then  observations  remained  suggest  and Northcote  that time was  occurred  before  3). 2.0  relatively comparable to  conditions, distributions  conditions distributions  hours  Figures 2 and  hours appeared to be a reasonable time for collecting observations  providing the distribution attained by later  (Appendix 8,  period  changed  relatively  were  (0.5 to 4.0  significantly  stable (Appendix  significantly  hours),  for the 8,  that the data collection schedule  (1981) was  not  first  1.0  Table  used  by  but  under to  1.5  5).  These  Kelso  (1972)  acceptable under the modified test conditions.  Salinity Preference  Test Sample Size, Exploration Time and  Gradient Stability  In past salinity preference experiments on gradient were examined for single fish of  5-12  fish  Woodall 1968, vertical  (Houston  1957,  Oncorhynchus, responses  (Otto and  Baggerman  1960,  Mclnerney 1970)  Mclnerney  1964,  to a  or schools Hurley  Williams 1969) using exploration periods of 1.0 to 2.0 hours.  gradient  tanks,  groups  of  pink  (O.  gorbuscha)  and  and In  sockeye  ((). nerka) juveniles were used to take advantage of the narrow distributions that  result  from  schooling  (Hurley  and  Woodal 1968,  however, are aggressive until after they smolt explain  why  Otto  and  Spieler  (1978) observed  Mclnerney  (1970) used  that, in a  Staaland  Williams 1969).  (Chapman 1962) single  fish.  channel,  test  error"  behaviour  increases  the  time  needed  to  this  may  Fivizzani  and  fish  grandis) explore each partition before moving to the next and and  and  search  Coho,  (Fundulus  that this "trial the  channel.  53  Perhaps  the intraspecific aggression displayed  by  coho could reduce  search  time by interrupting this tendency to explore each chamber.  To  determine  experiment,  an  groups  adequate of  1 to  sample 5  coho  channels in freshwater over a 4.0 number of coho that reached section increased with group group  may  size  and  were  observed  hour period  the opposite end size.  as  6).  From  from 0.5 to 4.0  To  check  8).  for this  explored  the  Generally, the  of a channel from the release  time required to reach the end of  hours, but as group  these observations, a standard  hours for a group of 5 coho was  they  (Appendix  majority of fish explored the channels within 1.0 to 2.0 Table  period  This suggests that interactions within the  reduce exploration time. . The  the channels ranged  exploration  size increased the  hours  exploration  (Appendix period  of  8, 2.0  established.  gradient stability, salinity  gradients were examined  before and  after 5 large coho juveniles were allowed to explore separate gradients of 0 to 20 ppt and 24  4 to 24 ppt for 24 hours.  hours, their activity was  The  results indicate that, even after  not sufficient to alter the gradient significantly  (Appendix 8, Table 7).  Timing of Distribution Observations  With  test groups  of 5 coho in 4 channels, only 20 observations could be  taken at any one time. sufficient  To arrive at a distribution within a salinity gradient  to indicate salinity preference, observations were collected over a  period of time and then pooled. coho  explored  narrower  range  an  entire  Qualitative observations suggested that once  channel,  of sections.  they  continued  Shifts in salinity  to explore  preference over  but  over  a  short term  54  observation periods, however, have been observed  for both sockeye (Williams  1969)  Consequently,  and  coho  conducted  (Houston  to determine  1957, how  Mclnerney  1964).  variable distributions  were after  tests were  the  2.0  hour  exploration period (Appendix 8).  The  standard  test procedure  fish documented every  distributions  (Appendix  8,  were  Table  used and  the position of two  15 minutes for 4 hours.  coho f r y were not significantly fry  was  distributions of Rosewall  different after 0.5  comparable  8).  The  It was  only  after  concluded  stocks of  hour, whereas Coldwater 1.5  that  hours  such  (STP  method)  observations  could  provide a salinity preference distribution if collected from 2 to 4 hours after the sample was  released to search a channel.  Possible Biases Caused by Preference Channel Design  After several months of collection and it became obvious bias  fish  confined results.  that the design of the modified Staaland channel tended  distributions to my  analysis of salinity preference data,  within the  methods, but  channel.  it should  be  This  problem  is probably  to not  kept in mind when examining the  Salinity preference data is affected by  a tendency for test fish to  limit their movements to the vicinity of the release chamber or to concentrate explorations near the confined ends of the various test devices. effect 1968,  is known  as  Williams 1969,  an  "end  Otto and  on"  The  aspects.  As  end  (Houston  Mclnerney 1970).  in 4 ppt seawater, coho tended channel.  effect  In my  Hurley  and  previously, counts  latter Woodall  tests in freshwater or  to prefer the release site or far end  on effect, however, was  described  1957,  The  of each  further modified by other design were  salinity present in a given section of the channel.  pooled  according  to  the  In most cases, this meant  55  that the number of observations at any that  salinity  section  plus  a  salinity was  proportion  of  the  made up of the count for  observations  adjoining sections where gradient shifts occurred. channel,  however,  the  count  included  the  from  the  At the release end  observations  in  two  two  of each sections  containing either fresh or 4 ppt salt water plus a portion of the observations from  the  first  gradient shift  section.  Because of this additional area,  counts for the release salinity were even higher than expected. at  the  high  end  of each  gradient  (20  or  24  the  In contrast,  ppt), the opposite  occurred.  Here counts included the observations from the last pure salinity section plus a  proportion  of  the  count  Consequently, channel on  effect and  for the  area was  accentuate  the  single  reduced  adjoining gradient  and  this tended  counts in the adjacent  shift section.  to reduce the  chamber  end  (Appendix  8,  Figure 4).  Design April  experiments on the salinity preference channels were carried out in  and  May.  During  this  period,  throughout the observation periods and fall and and  test  fish  explored  the  channels  seldom held position for long. By  the  winter, however, coho were more likely to explore to a certain point  then  remain  in one  section for the  entire  observation  increased the variability in replicate distributions. gradients  were  stable and  temperature  varied  period.  This  At this time, the salinity  by  less  than  1°C.  Thus,  gradient changes did not produce this effect and  it was  low  In other studies, gradients  winter  temperatures reducing  have been maintained (Otto and In my  fish activity.  throughout the year at a standard  temperature  (10°C)  Mclnerney 1970), possibly to standardize test fish response rates.  study,  however, seasonal temperature shifts may  development of behavioural responses and study  probably a result of  design.  be important  in the  so they were incorporated into the  56  Some of the compensated and  biases uncovered  for by  deleting  data  significantly  when  calibrating my  channel  design were  subtracting control distributions from test distributions, sets in which  different  control  (Appendix  9).  and  The  test modal  distributions  were  not  preferences  observed,  however, probably were still at least partially the result of design biases.  Potential Effects of Size and Growth  Seasonal differences in weight directly reached  (Folmar  and  at a given age  adaptation (Houston and  Dickhoff  1981)  (Donaldson  1977)  and  indirectly  has  been  through  threshold sizes  Size is important  in  seawater  survival (Parry 1960, Conte et al. 1966),  and  Size influences swimming  Mclnerney  or  (Conte et a l . 1966).  1960), seawater  time of smolting  1982).  can affect each of the traits studied either  Brannon  1976,  performance  suggested  Clarke and  in young  as  a  coho  possible  Shelbourn (Glova  trigger  initiating  behavioural changes associated with seaward movement (Bjornn 1971). also affects inter- and  intraspecific interactions  (Chapman  Genoe 1970) and thus can contribute to f r y displacement. size  are/is  correlated  with  transition  in  salinity  1962,  and  Size  Lister  and  Finally, age and/or  preference  (Hurley  and  Woodall 1968).  To  examine  variability  in  growth  of  the  groups  used  in this  study,  logio(weight) versus logio(time) were regressed for each experimental group (Appendix with  8, Table 9 and  analyses  sampled Rosewall Coldwater  were coho  Figures 5, 6 and  of covariance. significantly f r y appeared  River f r y .  The  different to grow  growth (p  <  7) and  compared among groups  trends  in the  0.001) (Appendix  faster  and  two 8,  wild  stocks  Table  10).  were heavier overall  than  Within incubation treatments, laboratory raised groups  57  of Coldwater  and Rosewall-Big Qualicum  coho used in each of the experimental  tests also showed .differences in growth. usually  the result  substantial compared Growth  of differences  as those  found  for experimental trends  significantly  within wild  different  groups were similar however,  in regression slopes  in the wild series coho  (at most  stocks.  within and  p  These observed  and  < 0.001),  are not sufficient  to cause  not as  were also  incubation  treatment.  while those  8, Table  but were trends  the 2°C incubated  (p > 0.05) (Appendix  probably  stock  Growth  differences were  11).  f r y groups  were  of 6°C incubated The differences,  serious variations  in the  ontogeny of the traits studied.  Since  size  captured caught  may  contribute to migratory  migratory  coho  at approximately  migrant  f r y caught  was  compared  to resident  the same time.  in the Coldwater  tendencies, the weight  of wild  f r y of the same stock  Samples included fall and spring  River, and spring migrants  caught in  Rosewall Creek.  Migrant and resident f r y did not differ in size within season  in the Coldwater  River  Table  12).  migrants may  Resident  in Rosewall  (t-test or Mann-Whitney U, p > 0.05) (Appendix f r y , however,  Creek  were heavier than  (Mann-Whitney U, p < 0.05).  8,  the corresponding Size, therefore,  contribute to the spring displacement of post-emergent coho in Rosewall  Creek, but not apparently in the Coldwater  system.  58  RESULTS  Plasma Sodium Regulatory Ability  Seawater  challenge  tests  for  wild  Rosewall  (Figure  (Figure 9) coho showed a general plateau in sodium  8)  Coldwater coho exhibited a tendency  Coldwater  regulation until smolting  begins during the first or second spring following emergence. and  and  Both Rosewall  for lower regulatory capabilities and  thus higher plasma sodium levels during the winter months.  Rosewall f r y showed a slow decrease in plasma sodium levels, indicating a slow increase in osmoregulatory ability, throughout the year. physiologically smolted as early as A p r i l 7 (aged 1). fry  required  caught. No  at least  2  years  to  smolt  and  Rosewall coho  In contrast, Coldwater  occasional  3 year  olds  coho smolted at one year in collections from the Coldwater  however, two  smolted, wild, 2 year old fish were caught and tested  were River;  (May  10  and June 7).  Fall (aged  (November 1) from  (Figure 9). seawater  17) subyearlings and  the Coldwater  a single spring  River were tested  in the  (April  10) migrant  seawater challenge  Fall migrants displayed less ability to regulate sodium  than corresponding resident  coho  (t-test,  levels in  p < 0.05), whereas the  spring migrant showed a lower, but not statistically different, plasma value than corresponding resident migrant  coho  from  Rosewall  Coldwater River were tested.  Creek  coho and  (t-test, no  p > 0.05)  migrant  age  1+  sodium  (Table 3). coho  from  No the  59a  Figure 8.  Seawater challenge test results for wild Rosewall Creek coho.  The horizontal line at 170 mM N a . L represents the plasma sodium level for physiologically smolted coho (Blackburn and Clarke 1977). Error bars represent 95% confidence limits. +  _ 1  Rosewall  Creek,  Age  0+  Wild  Coho  o o m —  •  —  o —  R e s i d e n t coho. SW  test  R e s i d e n t coho. FW  control  o in  ru  +  in  z  o o  CM  Cn ID  (0  E  IE  cn  (0  o in  SE-  o o  _L Apr  I  May  Jun  Jul  Aug  Sep  Oct Date  Nov  Dec  (1982-83)  Jan  Feb  Mar  Apr  May  Jun  60a  Figure 9.  Seawater challenge test results for wild Coldwater River coho.  The horizontal line at 170 mM Na .L~1 represents the plasma sodium level for physiologically smolted coho (Blackburn and Clarke 1977). Migrant results have been slightly offset from resident results to avoid confusion. Error bars represent 95% confidence limits. +  60  Coldwater  River,  Age 0+ W i l d  Coho  O  o m  sw t e s t  A A  o in ru  —  •  FW  control  A  Migrant  O  Resident  coho coho  SW t e s t  —  FW  control  E +  ID Z  ID  E  0) CD  o o  CM  o  "2P"  ID  _,.---  ffl  o j  D  Apr  Jun  Aug  Oct Date  Coldwater River, O O  — • —  m  Dec  t_  Feb  Apr  Jun  (19B2-B3)  Age 1+ W i l d R e s i d e n t coho,  Coho  SW t e s t  R e s i d e n t coho, FW  control  o ru  IT)  ro ID  E  0) ID  o o cxi o in  ©•  _  _  ffi--_  o o  - - - - gj  J  Apr  Jun  Aug  Oct Date  Dec (19B2-B3)  Feb  ©  l_  Apr  Jun  61  TABLE  3  COMPARISONS BETWEEN RESIDENT AND MIGRANT COLDWATER RIVER COHO SUBYEARLING PLASMA SODIUM CONCENTRATIONS.  Date (1982-1983)  Fry Capture  Sample Size  Status  April 30  Resident  Plasma Na  +  (mM.L ) -1  9  t-test Statistic  213.6 ± 4.13 t =2.242 s  p > 0.05 April 21  Migrant  1  184.2  Resident  6  210.2 + 7.03 +'5=3.03  November 17  p < 0.05 Migrant  2  231.3 ± 1.20  62  Wild Rosewall coho reached a weight Coldwater may  coho took two years to attained  be a variable influencing  changes with weight sorted  and  Creek  g within one year, whereas  a similar size range.  ion regulatory  capability,  were compared between stocks.  the mean  calculated and plotted Rosewall  of 7-11  plasma  sodium  (Figure 10).  values  Since size  sodium  regulatory  Coho of < 11 g were  for one  gram  divisions  were  Coho larger than 11 g were mostly from  and were too few to attempt  comparisons.  The values for  each population show considerable overlap in confidence limits throughout the size  range,  but average  plasma  sodium  Rosewall coho in the 7 to 11 g weight  Although over and  comparisons  of plasma  values were  consistently  lower in  range.  sodium  time potentially were confounded  levels  between wild populations  by the effects of differential  growth  size, such problems were less evident among laboratory reared stocks, at  least within incubation treatments. those  fish  Na .L , +  _ 1  levels),  that  were  When experimental groups were sorted for  physiologically  smolted  (arbitrarily  set as <  taking into account the slightly higher than expected plasma the coastal and interior  were comparable  smolt samples  in weight and length  within incubation  (Table 4).  175  mM  sodium  treatments  Mean lengths among smolt  groups were different (ANOVA, F =18.373, df=(5,57), p < 0.5), but pairwise s  comparison  tests  demonstrated  homogeneity  within  incubation  treatments.  Weight data were heteroscedastic but the Games and Howell approximate for equality of means again suggested homogeneity within incubation  test  groups.  All of the laboratory reared smolts reached sizes slightly larger than observed in  the wild  length). 80 mm  (greater  than  or equal to 7.3  g in weight  and  84.5 mm  in  These sizes were also larger than the critical smolting size of 70 to  suggested for coho by Conte et al. (1966).  63a  Figure 10.  Wild coho seawater challenge test results sorted by size classes  The horizontal line at 170 mM N a . L represents the plasma sodium level for physiologically smolted coho (Blackburn and Clarke 1977). The upper graph represents data from Rosewall Creek, while the lower graph is from Coldwater River coho. Error bars represent 95% confidence limits. +  _ 1  63  Rosewall  Creek,  Age 0+ W i l d  Coho  sw t e s t  — • —  FW c o n t r o l  ^""*-~ i  ^-"1—•  T  -  0  2  4  6  B  10  Weight (g)  Coldwater River,  Age 0+ W i l d  —  •  —  Coho  SW t e s t FW c o n t r o l  -G----0  4  6 Weight (g)  B  10  64  TABLE  4  COMPARISONS OF WEIGHT AND LENGTH MEASUREMENTS AMONG GROUPS OF PHYSIOLOGICALLY SMOLTED COHO.  3  Multiple Smolt Group  Sample  Weight  (g)  Size  Range Comparison'  Multiple Folk Length (mm)  5  Range Com par 1 son  0  Rosewa11 Creek, Lab Raised, 6°C  11  19.27 ±  13  1.358  122.5 ±  2.92  21.22  ± 0.863  127.3 ±  1.79  19  11.14  ±  103.5 ±  2.37  13  11.13 ± 0.497  101.2  ±  1.45  98.1  ±  7.26  -d-  13.50  -d-  Incubation.  Coldwater R i v e r , Lab Ral sed, 6°C  Incubation.  Rosewa11 Creek, Lab Raised, 2°C  0.716  Incubation.  Coldwater R i v e r , Lab Raised, 2°C  Incubation.  Rosewa11 Creek,  5  10.38  2  10.33 ±  ± 2.309  -d-  Wild Coho.  Coldwater  River,  4.010  -d-  101.5 ±  Wild Coho.  a - Smolted.coho were a r b i t r a r i l y a f t e r being tested  determined as those with _<175 ttM N a . L ~ ' In the plasma  In the seawater  +  challenge,  b - Games and Howell approximate test for equality of means, c - Tukey-Kramers method. d - Samples not Included  In comparisons, samples too s m a l l .  65  The  seawater  Figures in  challenge  11 and 12.  the literature.  results for laboratory  raised coho are given in  Generally the tested fish followed trends similar to those Among  the 6°C incubation  groups, there was a dramatic  early increase in May and June in ion regulatory capabilities, followed plateau  that  lasted  until  early A p r i l  towards the fully smolted condition.  when  plasma sodium  levels  by a  decreased  Once testing started in September and  October, the trend in plasma sodium levels in test fish of the 2°C incubation groups  (Figure  corresponding  12)  closely  followed  the  pattern  displayed  by  the  6°C incubation group (Figure 11).  Mean plasma sodium values for control samples for each stock, under each treatment, were usually within the 140 to 155 mM initial  experiments  187.0  ± 2.54 mM  Na .L +  Such high values and  for  each  group,  occurred  from  high, for  in and  coho  mean  in length.  During the  levels  juveniles, the smaller  and it is possible f r y and contributed  for the 6°C incubation  these early measurements, which  may  have  that  contamination  to the raised early  also contributed to the  groups been  (Figure 11). partially  plasma sodium levels.  development  treatments of sodium  Similarly, the trends were  not  regulatory  between stocks  different. ability  appears  Thus,  Except  contaminated  sampling, there were no differences within stocks in seasonal  among  reached  Some dexterity is required to  If such an error existed, it probably  early test values  during  range.  The samples with these high values usually were less than  when handling  sodium levels.  however,  _ 1  (Coldwater River, 6°C incubation group on May 4).  - 1  1.0 g in weight and less than 50 mm blood  +  are not reported in the literature (Conte et al. 1966, Miles  Smith 1968).  sample  Na .L  trends  both within  the physiological  to be fixed  within the  species and shows no differences between interior and coastal populations.  66a  Figure 11.  Seawater challenge test results for 6°C incubation, laboratory reared coho.  The horizontal line at 170 mM Na .L~1 represents the plasma sodium level for physiologically smolted coho (Blackburn and Clarke 1977). In the upper graph, data collected up until September were for Rosewall Creek coho. Data collected starting in November were for Big Qualicum River coho incubated and initially reared at the hatchery. Error bars represent 95% confidence limits. +  i.  66  Rosewall  C r . - B i g Qualicum  R.,  6°C I n c u b .  o  IT)  m —  o o m  •  sw t e s t  —  - - 0 - -  FW c o n t r o l  o in ru o o cvi o in o o  J  I  Apr  I  I  Jun  I  I  Aug  I  I  Oct Date  I  I  Dec  1  J  I  Feb  Apr  L  Jun  (19B2-B3)  Coldwater River,  6°C I n c u b a t i o n  o in m o o m  —•—  sw t e s t  - - 0 - -  FW c o n t r o l  o in o o ru o in o o  i  Apr  i  i  Jun  i  i  Aug  i  i  Oct Date  i  i  i  Dec (1982-83)  i  Feb  i  i  Apr  i  1—  Jun  67a  Figure 12.  Seawater challenge test results for 2°C incubation, laboratory reared coho.  The horizontal line at 170 mM N a . L represents the plasma sodium level for physiologically smolted coho (Blackburn and Clarke 1977). Error bars represent 95% confidence limits. +  - 1  67  Rosewall  Creek,  2°C I n c u b a t i o n  o in m  —•—  sw  o o m  +  ID  z  test  FW c o n t r o l  o m ru o o ru  ID  E  CO ID  o in o o Apr  Jun  Aug  Oct  Dec  Date  (1982-83)  Coldwater River,  Feb  Apr  Jun  2°C I n c u b a t i o n  O  in m  —  •  sw  —  --o--  o o m  test  FW c o n t r o l  o in ru ID  10  E  0) ID  o o ru o in o o  I  Apr  I  I  Jun  I  I  Aug  I  I  Oct Date  I  I  I  Dec (19B2-B3)  '  l  Feb  l  — I  '  Apr  Jun  68  Current Response  Differences in seasonal Fyke Rosewall  Creek  these two seaward  suggest  differences  coho stocks (Table 5). only in the spring  downstream  in  differences  may  increased  net catches between the Coldwater River and in migration timing  the  have  result  exist  Rosewall Creek coho appeared  (May),  both  may  whereas Coldwater  spring  (April)  from  and  fall  to migrate  River coho migrated (November).  passive downstream  flow velocities; however, the Coldwater  between  These  displacement  system  was  due  to  not in freshet  during either of the observed migratory periods.  When tested in the current response channels, resident wild coho from both Rosewall  Creek  and  the  variations in response  Coldwater  River  (Figures 13 and  showed  14).  both  diel  and  seasonal  Current response scores under  daylight conditions were usually greater than 10, indicating that the fish were either holding position or moving upstream. scores  were  Seasonally,  usually each  less  year,  than  10  During darkness, the response  indicating  subyearling  coho  a  from  net  downstream  both  strongest downstream responses during A p r i l and May.  streams  movement. showed  the  Notably, subyearling  coho from both stocks showed similar responses despite significant differences in  their  size.  Yearling  coho  from  the  Coldwater  system  also  showed  a  downstream response during the spring of their third year.  Current responses of spring migrant f r y , under both diurnal and nocturnal conditions, were usually different from the responses of resident f r y from the same drainage collected at the same time (Table 6). caught in the Fyke minnow  traps.  Migrant f r y were those  net trap, whereas resident f r y were usually caught with  This  distinction  is probably more valid  in Rosewall  Creek  69  TABLE 5 SEASONAL FYKE NET CATCHES OF COHO IN THE ROSEWALL CREEK AND COLDWATER RIVER.  Coho Catch Drainage System  Date (1980-1983) SubyearlIngs  Rosewa11 Creek.  Coldwater R i v e r .  3  January 15-16 March 11-12 March 28-29 May 11-12 July 20-21 October 2- 3 November 16-17  >1 Year Old  0 2 1 44 0 0 0  0 0 0 83 0 0 0  0 0  0 0  April 9-10 May 9-10 June 19-20  43 -b-b-  1 -b-b-  August 21-22 November 6- 7 November 27-28  7 37 18  0 0 0  February March  5- 6  4- 5  a - Coho subyearlIngs and older juveniles were a r b i t r a r i l y separated on the basis of s i z e , with size groupings determined from wild subsample agei ngs. b - The catch was omitted because the trap sank and probably biased the catch r e s u l t s .  70a  Figure 13.  Current response trends for wild Rosewall Creek coho.  Only subyearling f r y were tested. Resident f r y and migrant f r y were tested separately. Migrant f r y responses are slightly offset from resident responses to avoid confusion. A mean response of more than 10 indicates an upstream response, while a score of less than 10 indicates downstream movement. Error bars represent 95% confidence limits.  Rosewall A  Migrant coho. L i g h t  •  Migrant coho. •ark  •  in  Creek,  Age  0+ W i l d  Coho  conditions conditions  Resident  coho. L i g h t  Resident  coho. Dark  conditions conditions  X Apr  May  Jun  Jul  Aug  Sep  Oct Date  Nov  Dec  (1982-83)  Jan  Feb  Mar  Apr  May  Jun  71a  Figure 14.  Current response trends for wild Coldwater River coho.  The upper graph depicts the net current reponse of subyearling f r y , while the lower graph depicts the responses of age 1+ f r y . Resident f r y and migrant f r y were tested separately. Migrant f r y responses were slightly offset from resident responses to avoid confusion. A mean response score of more than 10 indicates an upstream response, while a score of less than 10 indicates downstream movement. Error bars represent 95% confidence limits.  71  Coldwater River, o c n  A Q  Age 0+ W i l d A A  Migrant coho R e s i d e n t coho  —  Coho  Light conditions •ark c o n d i t i o n s Light conditions •ark c o n d i t i o n s  O—  ID  E 3  <D 0)  C  o Q. 0) <U  rr  QJ  IT)  O  Apr  Jun  Aug  Oct  Dec  Date  (19B2-B3)  Coldwater River, o cu  Feb  Age  Apr  1+ W i l d  --0--  R e s i d e n t coho. L i g h t  —•—  R e s i d e n t coho. •ark  Jun  Coho conditions  conditions  C-  01 n a 0)  c  •a nai cr •u 0)  o  I  Apr  I  I  Jun  J  Aug  I  I  Oct Date  I  I  I  Dec (19B2-B3)  I  Feb  J  L  Apr  t_  Jun  72  TABLE 6 COMPARISONS OF CURRENT RESPONSES BETWEEN RESIDENT AND MIGRANT COHO SUBYEARLINGS WITHIN ILLUMINATION CONDITIONS AND POPULATION.  111umlnation Condition  Dlurnal  Popu1 at Ion Type and Capture Status Rosewa11 C r . , Resident.  Date (1982-1983)  Rosewa11 C r . , Resident.  May 30  Nocturna1  Diurnal  May 30  6  4.32 ± 0.302  6  2.42 ± 0.672  6  0.28 ± 0.088  12  8.92 ± 0.663  Coldwater R., Migrant.  April 22  6  3.83 ± 1.470  Coldwater R., Resident.  June 29  12  2.60 ± 0.615  Coldwater R., Migrant.  April 22  Coldwater R., Migrant.  a - Net Response Number.  Us  6.28 ± 0.783  June 29  Coldwater R., Resident.  s  32.5 p < 0.05  65 p < 0.01  2.597 p < 0.05  November 29  6  3.75 ± 0.911  6  14.60 ± 0.751 2.295 p < 0.05  Coldwater R., Migrant. Nocturnal  6  Coldwater R., Resident.  Coldwater R., Resident.  +  2.538 p < 0.05  Rosewa11 C r . , Migrant. Dlurnal  Current Response (NRN) a  Rosewa11 C r . , Migrant. Nocturnal  Sample Size  November 29  6  11.53 ± 1.104  6  8.56 ± 1.496 1.850 p > 0.05  6  5.62 ± 0.567  73  where the Fyke Fyke may  net was  set just above tidal influence.  net in the Coldwater  River, while moving downstream at that locality,  only have been redistributing themselves.  exhibited  a  greater downstream  conditions,  whereas  the  Coho caught in the  response  resident  coho  Spring migrant Coldwater f r y  than  resident  exhibited  a  f r y under greater  response than spring migrant f r y under nocturnal conditions.  diurnal  downstream  Spring migrant  Rosewall f r y showed greater downstream responses, compared to resident f r y , under  both  greater  light  and  downstream  comparable  dark  conditions.  responses  responses  drainages, it appears  under  than  Fall migrant  residents  nocturnal  under  Coldwater diurnal  conditions.  f r y showed  conditions  Generally,  that migrant f r y show stronger downstream  in  but both  responses  under both diurnal and nocturnal conditions.  Because relatively  the low  migrant),  net flows,  these  displacement.  current  responses  corresponded  responses  to  probably  of  wild  their  capture  were  not  migrant  a  Perhaps they reflect innate differences.  likely in the Coldwater River where there was resident  f r y , under  and  migrant  f r y (Appendix  f r y in the Coldwater  8,  conditions  of  (resident  or  status function  of  passive  This seems especially  no difference in size between  Table  12).  The  presence  River, but not in Rosewall Creek,  of fall  suggests a  difference in the pattern and timing of migration between these two stocks.  Seasonal patterns of current depicted in Figures 15 and were Under  evident between diurnal  treatments. observed,  16.  response  raised  coho are  Different seasonal trends in current response  illumination  conditions,  among laboratory  trends  conditions were  in each  usually  stock and  similar  among  treatment. stocks  and  First, a slight downstream response among the youngest f r y was then a net increase in response  score that progressively became  74a  Figure 15.  Current response trends for 6°C incubation, laboratory reared coho.  A mean response number of more than 10 indicates an upstream response, while a score of less than 10 indicates downstream movement. In the upper graph data collected up until September are from Rosewall Creek coho. Data collected starting in November are from Big Qualicum River coho incubated initially reared at the hatchery. Error bars represent 95% confidence limits.  74  Rosewall  Cr.-Big  Q u a l i c u m R.,  cou c n  6°C I n c u b .  —0--  Light  Conditions  — • —  Dark C o n d i t i o n s  in  B OJ  to c o a to a rr QJ  in  J  i  Apr  i  i  Jun  i  i  Aug  i  i  Oct •ate  in  i  i  Feb  i  i  Apr  L  Jun  (19B2-B3)  o cu 0)  i  Dec  Coldwater River,  n  i  6°C  Incubation  --O--  Light  Conditions  — • —  Dark C o n d i t i o n s  .A-  o--  co  n c •  D. CO 0)  cr  in  '  Apr  '  '  Jun  '  '  Aug  '  '  Oct Date  '  '  '  Dec (19B2-83)  I  Feb  I  I  Apr  I  I  Jun  75a  Figure 16.  Current response trends for 2°C incubation, laboratory reared coho.  A mean response number of more than 10 indicates an upstream response, while a score of less than 10 indicates downstream movement. Error bars represent 95% confidence limits.  75  Rosewall  Creek,  2°C  Incubation Light  Conditions  Dank C o n d i t i o n s  .1—  J  1  Apr  1  1  Jun  1  Aug  a:  i  1  Oct •ate  Coldwater  i  i  i  Dec  i  i  Feb  i  i  •  Apr  Jun  (19B2-B3)  River,  2°C  Incubation  --O--  Light  Conditions  — • —  Dark C o n d i t i o n s  4  J  Apr  I  I  Jun  I  L  Aug  J  Oct Date  I  I  Dec (19B2-B3)  I  I  Feb  L  Apr  Jun  76  larger then  from  the  initial  tests until September-October.  remained high during the winter months.  response  scores  response was  progressively  evident.  Coldwater  River,  decreasing  response  (Figure  15);  The  6°C  decreased  nocturnal  Rosewall  Creek-Big  described  above,  mean  net  (Figures  15  and  a  downstream  Qualicum  coho  River  that  The  scores  mean  net  animals  as  showed  early  for this  in the  as  a  January  group  never  during the second spring.  seasonal  16).  April-May  score  score  February-March, the  These  response  conditions, the  except  by  diurnal conditions  shifted to a downstream response (<10)  Under  and  treatment.  under  however, the  During  response  only exception to this daytime trend was  incubation  score  The  trend  in response  was  similar  to  were  lower  throughout  score  the  scores  for  diurnal trend  started at slightly  the under  indicating a slight downstream response among early post-emergent f r y .  year 10, The  scores then increase gradually through to November-December as more of the fry  began  scores  to successfully hold  progressively decreased  position. and  reached  Starting in February,  response  a maximum negative rheotaxis in  May.  Seasonal trends in nocturnal current response in Coldwater River coho, for both  incubation  corresponding  treatments  (Figures  Rosewall Creek-Big  15  and  16),  differed  Qualicum River trends.  Up  from  the  to October, the  nocturnal response scores of the interior stock were similar to those of the coastal stocks. fry  became  increased.  more During  score occurred score  They started with a slight downstream response but, as the  suggests  successful  at  holding  November, however, a sharp  in both incubation treatment a  position,  switch  from  a  positive  a  scores  gradually  drop in the mean response  groups. to  the  This drop in response  strong  negative rheotactic  77  response.  The  downstream  early spring and  response  continued  became more moderate only  throughout  the  winter  as the corresponding  and  upstream  positive response under diurnal conditions decreased.  The  laboratory  treatments not  results demonstrate that the effects of the two  (i.e. coastal vs. interior temperature regimes) within stocks were  significantly different.  conditions  were  Throughout day.  The  second  the two  spring  Thus, trends  generally year,  the  same  for  coho fry hold  exceptions  in current response under diurnal each  stock  and  are recently emerged f r y and  (April-May). under  In  treatment  position or move upstream  contrast  nocturnal  to  response  conditions  differ  stocks.  Coldwater coho showed a shift to negative  group.  during  the  juvenile fish in the  diurnal conditions,  current  trends  dramatically  in  between  rheotaxis in November or  about 3 months earlier than observed among coastal coho. stocks  incubation  Again, because the  were raised under identical environmental conditions, these observed  differences in current responses between stocks are presumed to be innate.  Salinity  Preference  Wild coho fry prefer salinities in the 0-8 year  but  levels and  shift  (Figures  subyearling  in late  winter  17 and  18).  and  seawater in a 0-20 ppt  seawater  When  a  by  this  time preferences  a  towards  The  of 4-24  up  (Figure  18)  only exception was  ppt  for salinities of 4-8 shifted  isotonic and  Rosewall Creek coho  Rosewall Creek  gradient  stocks showed preferences At  Subyearling  ppt gradient.  with  spring  yearling Coldwater coho  displayed  presented  and  ppt range throughout most of the  to 12-16  hypertonic (Figure  preferred  0-8  17), ppt  a preference for 12  coho sample on  February  10.  seawater, however, both wild ppt until late A p r i l and ppt.  Generally,  May.  migrant fry  78a  Figure 17.  Salinity preference trends for wild Rosewall Creek coho.  Only subyearling f r y were tested. Resident f r y and migrant f r y were tested separately. Migrant f r y responses were slightly offset from from resident responses to avoid confusion. The horizontal line at 12 ppt seawater is the upper limit of the isotonicity range. A smoothing program (lowess in S) was used to draw the best fit lines.  Rosewall  Creek. A  —•— A --0--  Age  0+  Wild  Coho  M i g r a n t coho. 4-24 p p t g r a d i e n t Resident  coho. 4-24 p p t g r a d i e n t  M i g r a n t coho. 0-20 ppt g r a d i e n t Resident  coho. 0-20 p p t g r a d i e n t  79a  Figure 18.  Salinity preference trends for wild Coldwater River coho.  The upper graph depicts the net salinity preference of subyearling f r y , while the lower graph depicts the responses of age 1+ f r y . Resident f r y and migrant f r y were tested separately. Where necessary responses were slightly offset from each other in order to avoid confusion. The horizontal line at 12 ppt seawater is the upper limit of the isotonicity range. A smoothing program (lowess in S) was used to draw the best fit lines.  79  Coldwater River, A  M i g r a n t coho. 4-24  I  Apr  A --Q--  M i g r a n t coho, 0-20 ppt g r a d i e n t R e s i d e n t coho, 0-20 ppt g r a d i e n t  I  I  I  ppt g r a d i e n t  Aug  ^ I  I  Oct  —  •  —  o  i  Jun  i  i  Aug  O  i  i  Oct Date  I  I  Dec  I  I  Feb  I  I  Apr  L  Jun  (1982-83)  Coldwater River,  Apr  4-24  Of" I  Jun  i  ppt g r a d i e n t  R e s i d e n t coho,  Date  i  Coho  — • —  A 1  Age •+ W i l d  Age 1+ W i l d  Coho  R e s i d e n t coho. 4-24  ppt g r a d i e n t  R e s i d e n t coho,  ppt g r a d i e n t  ""-Qi i  i  Dec (1982-83)  0-20  t>" i  Feb  i  i  Apr  i  i—  Jun  80  from  both  populations preferred hypotonic  salinities  (0-8  ppt) in both  test  gradients.  Salinity preference trends over time among laboratory raised coho are shown in Figures 19 and  20.  No significant  were observed  between  data  2°C  from  the  (Figure 20).  differences in salinity preference trends  incubation treatments  incubated  in either  stock, although  coho were more variable  for both  Significant variation between stocks, however, was  the  populations observed.  Generally, the data for laboratory raised Rosewall Creek-Big Qualicum River coho are similar to both my  wild fish data and  literature  data.  For most of  the study, Rosewall Creek-Big Qualicum River coho juveniles, when presented with a 0-20 in  ppt gradient, preferred 0-4  preferred salinities to 8-12  (Figure 20) and  on May  preferences in the 4-24 fall and 8-16  winter at 4-12  ppt.  occurred  The on  ppt on A p r i l  ppt,  with an  9 for the 6°C  Laboratory raised Coldwater  after  spring and  31  preferred  0-8  ppt  in 0-20  ppt,  preferences  during  incubation treatment  group Salinity  the  spring to  second  (Figure 20)  spring and  on  (Figure 19).  coho also preferred hypotonic salinities during  From November  ppt seawater in a 0-20  gradient (Figure 19).  then increased to 12-16  incubated  increase during the second  following emergence, but  November-December.  (October  4-24  summer  21 for the 2°C  an increase  ppt gradient were higher during the spring, summer,  A p r i l 17 for the 2°C incubation treatment  the  There was  8 for the 6°C incubated group (Figure 19).  increase in salinity  March  ppt seawater.  May  until  5 in 4-24  preferred higher  October  ppt in both gradients.  early  November  ppt) coho incubated  ppt gradient and  With a few  or  salinities  4-8  at  6°C  ppt seawater in a  exceptions, salinity  preferences  81a  Figure 19.  Salinity preference trends for 6°C incubation, laboratory reared coho.  The horizontal line at 12 ppt seawater is the upper limit of the isotonicity range. A smoothing program (lowess in S) was used to draw the best fit lines. In the upper graph, data collected up until September are from Rosewall Creek. Data collected starting in November are from Big Qualicum River coho incubated and initially reared at the hatchery.  81  Rosewall  Cr.-Big  Q u a l i c u m R., 6°C I n c u b .  in ru  4-24 p p t grarJlent 0-20 p p t g r a d i e n t  o ru in  in o  cm _tp___o h  J  -o—ot_c>  o I  Apr  o_ o  I  I  Jun  I  I  Aug  I  I  Oct Date  I  o  I  Dec  ©  I  Feb  '  l  l  Apr  '  Jun  (1982-83)  Coldwater River, in ru o ru  6°C I n c u b a t i o n — • —  4-24 p p t g r a d i e n t  — Q —  0-20 p p t g r a d i e n t  in  in  J  Apr  I  '  Jun  '  '  Aug  I  I  Oct Date  L  J  Dec (1982-83)  I  Feb  I  I  Apr  I  L  Jun  82a  Figure 20.  Salinity preference trends for 2°C incubation, laboratory reared coho.  The horizontal line at 12 ppt is the upper limit of the isotonicity range. A smoothing program (lowess in S) was used to draw the best fit lines.  82  Rosewall  Creek,  2°C  Incubation  in CVJ  a n. a) u c <u c.  o cu  — • —  4-24 ppt g r a d i e n t  — O —  0-20 ppt g r a d i e n t  in  0)  u c.  a.  o  >  in  cm  <3»  ID  o  o ~o~ o i  Apr  i  i  Jun  i  i  i  Aug  [_  J  Oct  Dec  Date  (1982-83)  Coldwater River,  I  Feb  2°C  I  L  Apr  Jun  Incubation  in C\J  4-24 ppt g r a d i e n t  4J  a. a.  •-0--  o  0-20 ppt g r a d i e n t  OJ 03 U  c 0) c  in  0) >*0)  c  Q. >» •p  in ID CO  o  O  O J  Apr  Jun  Aug  L  J  I  I  Oct  Dec  Date  (19B2-B3)  L  Feb  J  Apr  I  L  Jun  83  Coldwater coho incubated at 2°C also shifted to higher salinity preferences after mid-October preferred  0-4  preferences ppt  (Figure 20).  ppt  (0-16  salinities  These fish,  from  July  tested in a 0-20  to November  ppt) beginning December 22.  gradient preferred 4-8  after October 16 they  ppt  and  ppt  a  wide  range  Those coho tested in a  seawater during August and  preferred 8-16  gradient,  ppt seawater.  The  of 4-24  September,  but  drop in preference  exhibited by the best fit lines in the lower graph in Figure 20 are a response to low  salinity, final preference points.  occurred  as  a  result  seawater observed distributions 9).  were  In the 0-20  of  on May not ppt  with a second, and  the  In the 4-24  elimination of  30. This point was  significantly  a  ppt gradient, the drop  final  preference  of  20  omitted because test and  different  (t =1.93, p >  0.05,  s  ppt  control  Appendix  gradient, the final preference distribution was  bimodal  not substantially different, peak at 20 ppt.  Generally, Rosewall Creek-Big Qualicum River coho salinity preference data indicate  that  throughout  coastal  subyearling  most of the  coho  rearing period.  preferences increase from hypotonic particularly  if freshwater  stronger  hypertonic  gradient  support  preference  for  Mclnerney's is  salinities  In their  second  up  to  isotonicity  spring, however,  to isotonic or even hypertonic salinities,  is eliminated  preferences  seawater  prefer  from  available  gradient.  The  spring  observed  in the  4-24  ppt  (1964) suggestion  that the  development  of a  a  in the  the  biphasic  process  involving  acclimation  to  increasing salinities.  Interior coho, represent by the Coldwater stock, exhibit a shift in salinity preferences than  to isotonic and  observed  in  hypertonic  coastal populations.  levels  at least  The  earliest  three months earlier shift  in  preference  84  occurred Figure 4-8  in 20).  ppt  to  November 16.  Coldwater These 12-16  coho  coho ppt  incubated  showed  in  a  an  4-24  under  increase ppt  interior  conditions  in preferred  seawater  gradient  (2°C,  salinity as  early  from as  85  DISCUSSION  The  results  suggest  there is little difference in the  three characters monitored downstream timing. in  between the wild populations  Both Rosewall and  the spring (Figures 8 and  Rosewall Creek coho smolted with  previous  contrast  observations  to the  streams.  9) at a mean weight of about 10 g  for  were  no  coho  (Ricker  significant  1972),  and  by  Scholz  downstream and  the literature  differences  but  responses  during  (Figures  13  and  spring 14).  ppt  showed shifts to isotonic and  these  data  agree  with  catches,  trends  1960,  Mclnerney  however,  differed  Creek, emigrant f r y and Coldwater these  resident  fry  may  Taft 1954, both  coho  Mason  populations  from  1964,  Otto  between  the  in  the  and two  showed  stronger  (Table 6).  both  study  Hasler net  streams  18).  Again,  (Houston  streams.  downstream  year,  seawater) in  1970).  in A p r i l and  1957,  Fyke In  Rosewall  November, responses  to passive  to inherited differences between the two  net  (Table 5).  These laboratory data  downstream responses were not due  As  post-emergent f r y  literature  study  downstream  both  exhibited  (12-16 ppt  Mclnerney  in  resident  1975,  yearlings were caught only during May  generally  have been due  wild  seawater range during most of the  described  f r y in laboratory tests  that the observed  between  (April-June) as  Wild  is somewhat  ppt gradient (Figures 17 and  f r y were caught moving  migrant  but  salinity preference.  hypertonic levels  if provided with a 4-24  Baggerman  and  the  salinities in the 0-8  April-May,  and  1983), wild coho juveniles from  yearlings  preferred  (Shapavolov  River  among returning adults to  populations in the ontogeny of current response and described  (Table 4).  This geographic variation agrees  predominance of sub-2 fish  There  smolted  as yearlings, while Coldwater  years in freshwater.  the  studied, except for  Coldwater coho physiologically  coho, however, smolted  after two  development of  and than  suggest  displacement populations.  86  Under coastal  laboratory  and  rearing  interior  coho  conditions,  stocks  regulation or diurnal current in  the  pattern  Throughout  during  continuing  the  fall  daytime  responses may in  and  River)  the  15  and  by  a  16).  current  of  winter  freshet  activity and  plasma  sodium  responses and  hypertonic  These  salinities  fry  (Figures  coastal  (Rosewall  moved  upstream  also  exhibited 20).  or re-establishing  conditions.  the  salinities.  19 and  a shift to hypertonic  until the spring following emergence.  accompanied  ontogeny  coho held position at night and  of  progressive,  differences between  emergence,  a means of maintaining  face  no  There were, however, differences  following  for hypotonic  provide  downstream migratory  slow, but  the  to isotonic and  winter  (Figures  preference  residence  responses.  from hypotonic  Qualicum  the  in either  were  of development of both nocturnal  shift in preference  Creek-Big  there  a  These  freshwater  Coastal  coho  delay  salinity  preferences  Starting in late February, there was  a  shift to a net downstream movement during the night  preference  for  higher  salinities.  At  first  this  current  response is offset by continuing diurnal upstream movement, but ultimately an overall downstream movement occurs in late April and coastal  yearling coho  are  seawater (Figures 11 and data and  downstream continuing  The shift  raised responses  of  ion  regulation in  This scenario is compatible with both my  Coldwater  River  beginning  in the  throughout the  current  nocturnal in  12).  physiologically capable  At this time, the  wild  the literature.  Laboratory  Daytime  also  May.  salinity  shifted  rheotaxis  preference  exhibited  November  following winter  responses  negative  coho  strong  following emergence  and  spring  (Figures  downstream  in the  spring  observed  was  to isotonic and  nocturnal  accompanied  hypertonic  by  levels  15 and  and 16).  (April-June). a November (Figures  19  87  and  20).  during  Again  downstream responses occurred  the period when interior  capabilities  during  both  day and night  coho have established smolt  osmoregulatory  (Figures 11 and 12) and, therefore, are prepared  to move into  salt water.  The  differences  between  Coldwater coho are probably differed  from  the results  for wild  natural conditions,  coho caught in the Coldwater  and may  the  potential  densities,  River may  also  The few physiologically  until  overwintering  involved  in overwinter  low temperatures and low food  survival  availability  of  smolted  due to a delay  in the  residents are  (Zaugg and McLain 1970, Chrisp and Bjornn  stress  raised  be due to sequencing  have been  of ion regulatory capabilities  migrating seaward  laboratory  a result of laboratory rearing conditions, which  component changes in the smolting process.  development  and  1978).  at relatively  (Rosenau  Given high  et al. 1986,  Swales et al. 1986), as well, as the long migration distance, a delay in the physiological  transition  to the smolt  condition might  conserve  energy.  In  contrast, Rosewall Creek coho have a much shorter migratory distance and so must  be fully  yearling  prepared  emigration  to enter the sea during  occurs.  Hence  the spring when the usual  the more frequent  smolt  plasma sodium  levels among the 7 to 11 g coho sampled in Rosewall Creek (Figure 10).  The  strong negative nocturnal current response and preference for higher  salinities observed fall and winter  among laboratory raised  suggests  that, provided  Coldwater River coho during the  the appropriate stimulus is present,  Coldwater f r y will show a continual shift in behavioural responses once these are initiated.  Wild  f r y also exhibited downstream movement, but only in a  portion of the population during November.  Wild migrant f r y , however, did  88  not  show  higher  salinity  behavioural responses  preferences  may  at this  time  which  not be strongly developed  suggests  that the  at the locality these f r y  were caught.  Interior coho, at least those in the Coldwater  River, either overwinter in  peripheral habitats, such as sidechannels and off-channel ponds that are both areally restricted and  probably transitory (Swales et al. 1986,  1986), or migrate downstream in the fall. for  the  upper  variations emigrant  in interior Coldwater  December  drainage  coho  life  appear history.  be  captured  from the Coldwater  system  to  (M.  Sheng  limited survey  support  During  River coho in November  coho could only  Fall emigrants Nicola  Fraser  The  Rosenau et al.  my  the  above  field  (Table 5) and  in sidechannels  data available  work,  and  beaver  Coldwater  emigrants  must  comm.).  Whelen and either  find  peripheral to the main rivers enroute lower and In  Fraser  And  coho  generally  Slaney  1986).  ponds.  alternative  do  not  upper Fraser  Consequently,  overwintering  fall  habitat  or continue downstream as far as the  River where overwintering habitat is probably  coho would be  by  River do not simply shift downstream to the  pers.  (Beniston et al. 1985,  I caught  noticed that  overwinter in the mainstem Thompson River or the central and River  described  more extensive  better positioned for a seaward migration in the spring.  the latter locality, however, there has been no evidence that coho rearing  densities increase during the winter (Northcote et al. 1978).  Similar migrations have been observed Washington 1984, and  (Cederholm and  Scarlett and alternative  Scarlett  Cederholm  rearing  1984).  1982, The  in the Clearwater Peterson  1982,  frequency  habitat in the lower  reaches  River system in  Peterson  and  Reid  of accessible tributaries of large Pacific coast  89  rivers,  such  interior  as  the Fraser River, may  overwintering  conditions.  The  conditions in the upper reaches may the available overwintering over  time and  Coldwater have  evolved  Sidechannels  flows were observed  Cederholm  such  severity  and  of  the  of  severe  overwintering  be amplified by the transitory nature of  habitats.  groundwater  River.  act to buffer the impact  Scarlett  variable migration  and  beaver ponds fill in  to be  discontinuous in the  (1982) suggest  behaviour  that coho salmon  to assure  survival in just  such a relatively unstable environment.  The  existence  questions control  regarding such  environmental are,  they  which  of  such the  variable downstream environmental  genetically  based  I used.  migration  that  1981,  Raleigh and Northcote  (Chapman  1962,  Wedemeyer et al. 1980). may  daylength  migratory and  environmental  to  (Hoar 1976,  the  interactions  Brannon Kelso and  Generally,  be  Mason and  passive  Chapman 1965)  1967  often  and  1972,  Northcote  1981,  however, outcome  downstream of  territorial  or a component of the  Folmar and Dickhoff 1980,  Scholz  1980,  Active migration in coho is associated with smolting  timing  temperature cues  1965,  Chapman 1971,  be endogenous (Scholz 1980,  downstream  (Groot  1981).  is considered  process of smolt formation  and  among interior coho  environmental-genetic  in coho  aggression  the  It is known  1971,  al.  Whatever  under the laboratory rearing conditions  Raleigh  et  that  to have occurred  activity in salmonids  1967 and  raises  mechanisms  responses.  cues that trigger fall downstream responses  appear  behaviour  physiological  behavioural  control migratory  Kelso  and  migration  are,  Hasler and however,  (Hasler and  also trigger  the  streams such as the Coldwater River.  Scholz  fall  Scholz 1983).  fine-tuned 1983).  emigration  by  Smolting such  cues  Perhaps these of  coho  from  and as  same  interior  90  In  coho,  the  development  of  the  characteristics  downstream  movement,  are  closely  photoperiod  (Baggerman  1960,  Conte et al. 1966,  et  a l . 1979,  Scholz  1980).  Fall  synchronized  migrant  coho  of  smolts,  with  an  including  increase  Clarke et al. 1978, from  the  Coldwater  in  Ewing River,  however, were experiencing a decreasing photoperiod, as were the laboratory raised  stocks which showed a fall shift in behavioural responses.  decreasing  photoperiod  habitats should  serves  as  a  cue,  also have emigrated  then  But if a  residents in the peripheral  in the fall but  didn't.  It is unlikely,  therefore, that photoperiod shifts act to initiate fall emigrations.  Northcote temperature trout and  (1962)  and  sockeye  salmon.  of 4-5°C  demonstrated  and  more to delay and  Bardach  and  Keenleyside and  could induce  salmon; however, Zaugg  Yet  (1967)  in explaining the variable migratory  temperature  serves  Raleigh  Bjorklund  (1957  importance  patterns found  smolting activities than by  Raleigh  a rise in  to current in coho  (1976) showed that in coho  cited  of  in rainbow  (1954) suggested  a negative response  McLain  prolong  Hoar  the  temperature  to initiate them.  1967)  suggested  that  salmonids, in general, move downstream in the early winter into deeper water to  avoid  extremely  low  temperatures.  It is possible,  then,  that in the  Coldwater  River coho leave the mainstem river during the winter to avoid the  extremely  cold  winter  temperatures  in the main river  During winter collection trips, I observed Coldwater either why  River were a often a few  groundwater overwintering  off-channel habitats.  (Table 2,  that habitats peripheral to the main  degrees  warmer, probably  seepage or vegetation decomposition. coho  in the  Figure 5).  Coldwater  River  were  because of  This may only  found  explain in  the  91  The  problem  downstream  with  temperature  as  migration is just how  the  environmental cue  such a cue might work.  that  triggers  If a decreasing  temperature regime is the cue, then coho residing in both peripheral habitats and the main river should emigrate together. same seasonal temperature habitat may  always  be  fluctuations  Both environments undergo the  (Figure  slightly warmer.  If a low  critical to downstream movement, as shown by and  5), although the threshold  peripheral  temperature is  Northcote (1962) and  Raleigh  Chapman (1971) for trout species, then the laboratory raised coho, which  were  reared  Coldwater negative  at warmer  temperatures  overwintering areas and rheotaxis  in the fall.  than  observed  the main  in both the peripheral  river,  should not have shown  Since the observed  migrant  timing  of the  various interior coho groups doesn't fit any of these descriptions, temperature cues do not appear to trigger emigration.  Other  possible  cues  which  may  be  instrumental  include size, rearing density and current velocity. or  threshold  size,  including seaward important  to  fall  in initiating emigration Size, particularly critical  has been shown to be important to salmon migration (Folmar and Dickhoff 1980). movements,  then  the  coho  that  smoltification,  If threshold size is were  caught  moving  downstream should have been significantly larger than those that remained as residents. were  Certainly laboratory raised coho, from both incubation treatments,  significantly  (Appendix  8,  larger  Figures  than  5, 6 and  wild 7).  Coldwater  coho  of  the  same  age  Fall migrants caught in the Coldwater  River, however, were not significantly different in size from residents caught on  the same field  trip  (Appendix  8, Table 12).  Size, therefore, does not  appear to contribute to the initiation of fall emigration.  92  Coho can  are territorial  result  during  in aggression  freshwater  and  residence and increased  f r y displacement  densities were high in laboratory rearing tanks  (Chapman  densities  1962).  Since  (up to 1.5 to 2.6 fish.L"!,  Appendix  5), aggressive interactions may explain the downstream  observed  in the experiments.  Natural densities  recorded  responses  by Swales et a l .  (1986) in overwintering ponds peripheral to the main Coldwater River during the fall of 1984 were as high as 1.53 fish.m" 3 (assuming the ponds 1.0 m in depth).  The laboratory rearing densities were, therefore, about two  magnitudes higher than observed as  averaged  major overwintering  areas  in the wild.  These off-channel ponds serve  in the Coldwater  system and it is conceivable  that, once a critical density has been reached,  excess f r y begin to emigrate.  Swales  that most juvenile coho move  (pers. comm.), however, has observed  into the overwintering areas in the Coldwater River during high waters in the early summer rather than  in the late summer and fall.  occur,  then  emigration  should  take  place  earlier  If critical densities  in the year  as densities  increase, not during the fall.  Brannon thresholds sockeye  (1967 and 1972) demonstrated that stock specific current velocity are important  stock  downstream velocities  responds  unless  above  that  in directing to a  sockeye f r y to nursery  different  threshold  velocity  threshold  is encountered.  the threshold, they  show positive  When  areas. and  f r y move  they  encounter  rheotaxis.  similar mechanism is at work during the fall in coho stocks.  Each  Perhaps a  In the Coldwater  River, discharge levels decrease after the May-June freshet period (Figure 3) to  less  than  1 m.s~l i n August  and September  (Anon.  1982).  Discharge  levels then increase again and peak in early November before dropping off for the  winter.  If we  assume  that  discharge  levels  are directly  related to  93  changes in current velocity and  if Coldwater coho emigration  is triggered  water velocities falling below some threshold, then mainstem residents migrate during low  discharge  August and periods).  where currents prepared  are  September or in December to February  should  (the  generally lower Since  than  in the  main river  neither situation is observed  should  also  1972)  increases,  in rheotaxis  tanks  were  however,  just  prior  to the  may  from  act  increased  were observed.  increased  by  are unlikely amongst coho.  laboratory migrants experienced shifts  be  in the Coldwater  system, velocity threshold cues acting in a manner similar to that reported  Velocity  two  At the same time, coho residing in peripheral areas  to emigrate.  Brannon (1967 and  by  5-6  as  a  cue  since  both  wild  and  flows in the fall at about the time  In the laboratory, flow rates in rearing  L.min  -1  change to downstream  to  8-10  L.min  nocturnal  -1  current  during  October,  responses among  Coldwater coho.  Another question the  the data pose is why  salinity preferences  fall among coho that at that time are located over 400  (Figures  15 and  16).  Mclnerney's (1964) suggestion  should km  from the  that salinity  reached.  The  characteristics thyroid  answer may  normally  extract or  TSH  lie in the hormonal regulation of  associated  with  to juvenile coho causes an  movement, a reduction in aggression (Hasler and for  Scholz  abandoning  1983).  stream  smolting.  and  and  moving  showed that an increase in thyroid activity was  estuary  behavioural  administration  of  increase in downstream  an increase in schooling  A l l of these behavioural  residence  The  sea  preference  acts as a migrational orientation mechanism can only operate once the is  shift in  responses are  seaward.  behaviour necessary  Baggerman  (1960)  correlated with a shift from a  94  preference coho.  for freshwater  The  to a preference  administration of TSH  for 18-24  ppt seawater in yearling  resulted in a similar shift in subyearling  coho (Baggerman 1963).  Perhaps then, the early shifts in salinity  observed  in  raised  hormonal  regulation of  laboratory  Coldwater  migratory  laboratory raised coho also may  coho  responses.  have occurred  were  a  Salinity  side  lack  of  differences in  preference  effect  preference  of  the  shifts in  slightly later than changes in  rheotactic responses (compare Figure 16 with Figure 20). the  preference  observed  between  This could explain fall  migrant  and  resident wild f r y (Figure 18).  Finally, the question arises as to whether fall migrant coho are sufficiently imprinted  on  the  Coldwater River  to home as adults and  continuing recruitment.  This is a necessary  and  genetic  maintenance of the  believed Duncan  to imprint 1971,  on  their  discreteness  natal stream  Mighell 1975).  Scholz  thus contribute to  prerequisite to the development of the  during  population.  smoltification  Coho (Jensen  are and  (1980), however, suggests that thyroid  activity is not only responsible for a downstream current response in smolting coho, but  also may  be  instrumental  in olfactory imprinting.  If this is so,  then increased thyroid activity could explain not only the observed shifts in nocturnal  current  response  and  salinity  preference  in Coldwater  coho,  but  also act to assure juveniles imprint on the stream prior to emigration.  The salmon suggest the  results of this study populations that the  species.  functional  The  in the  not only  ontogeny  of  demonstrate differences between coho behavioural  characteristics  but  development of ion regulatory capabilities are fixed behavioural  variations  that  data are particularly important  could  affect  stock  fitness.  also  within  in pointing to The  observed  95  differences inherited  in  the  development  component  differences deserve thyroid  activity  investigations  of  and  of  this  behavioural  implies  further study and  in  fall  migrant  the  mechanisms  an  two  and  adaptive  clearly  have  significance.  an  Such  promising areas are comparisons of resident  responsible  behavioural responses in different stocks. to  responses  interior  coho  for initiating  and  fry,  and  maintaining  Ultimately, it would be interesting  determine the proportionate contribution to production by fall migrant  and  winter resident interior coho groups.  This  study  also  points  to  variations within species and While smolting has 1976)  involving  changes been  series  production  to the  of  imprinting and species.  3-4  month  (eg. Scholz 1980).  coastal populations,  morphological,  period  physiological and  preceding  and  behavioural  coincident with  has smolt  has  lead to conclusions  on  the timing of  Indeed, even with the recent considerations of variable life history (Peterson  1980  and  1982,  Cederholm  a stream  prior  responses to environmental  the development of ion regulation). stock  specific  life  and  Scarlett  that stock production is determined  some habitat limiting factor.  capacity to imprint on  exhibit  (Hoar  the process  to the  by  If, however, coho have smolting  phase, they  stimuli in such a way  can  as to optimize  survival while still meeting an endogenous physiological schedule  to  history  emigration that are not necessarily representative of the entire  within coho stocks  their  life  Since most of the work has been conducted on  this approach  spawning numbers and  vary  investigating  as a dynamic, metamorphic process  1981), it generally has been concluded  the  of  of not studying life history stages in isolation.  been recognised a  importance  (Wedemeyer et al. 1980), most of the research on  limited  forms  the  (in this case  Other Pacific salmon species also appear  history  variations.  Because  chinook  salmon  96  emigrate  as  f r y or  variable times. least  ability  (Healey  1983),  they  probably  also imprint at  Again, these differences in migratory timing appear to be at  partially  population  smolts  genetic  (E.B.  Taylor  differences also may  between  ocean- and  pers.  occur  comm.).  in the  Recent work  development of  stream-type chinook  suggests  osmoregulatory  (Wagner et al. 1969,  W.C.  Clarke pers. comm.).  The  results of this study serve to support Raleigh's (1971) suggestion that  populations of fish of the same species should not be viewed as "genetic and behavioural equivalents". it should  be assumed that each population is adapted to the requirements  its specific habitat. salinity other  preference  diadromous  Fraser  Instead, unless there is evidence to the contrary,  River  Population differences in the ontogeny of migratory responses  fishes.  also may For  steelhead  and  Williscroft  1977,  example,  populations  components of current response Northcote  and  changes in salinity  lamprey  (Entosphenus are  ontogeny  behaviour  habitats.  of  at  least  partially  that  allow  stamina  this  could  varies between  affect  directional  1981).  In  grunion  (1974) observed  Tsuyuki  (Leuresthes  that different  influence habitat use.  Perhaps  in Pacific fishes as diverse as the Pacific  trldentatus)  thaleichthys)  swimming  Thomson  preferences  the variable life histories observed  for habitat selection in  (Huzyk and T s u y u k i 1974,  Kelso  and  important  and  behaviour  sardina) populations, Reynolds and ontogenetic  be  of  and due these  the to  longfin  population  species  to  smelt  (Spirinchus  differences in  exploit  a  variety  the of  97  CONCLUSIONS  1) There is no evidence for differences in the development of ion regulatory ability  between wild,  resident  coastal and interior coho populations  the data are analysed by weight.  In the spring, both populations  when  develop  sodium regulatory ability in the 7-11 g weight range.  2) There  are differences  in the age of smolting  between  wild  populations.  Rosewall Creek coho smolt after one year in freshwater, whereas Coldwater River  coho may  Smolts in both  require  2 years of stream  populations  residence  to reach smolt size.  average about 10 g in weight and 100 mm in  fork length.  3) In  laboratory  development stocks, show  or an  raised  coho  of sodium between  groups,  regulatory  incubation  acclimative  phase  emergence, an overwintering following  4) There  and interior  Rosewall  Creek  post-emergents  ability  between  treatments  in  the  plateau  in the timing  coho  coho  stocks.  migrate  and yearlings,  downstream in both the spring tested  are no  within  summer  differences coastal  stocks.  and  and reach  and  in the interior  A l l groups  early  fall  following  smolt capabilities in the  April-June.  are differences  coastal  there  wild  migrant  of downstream As  indicated  downstream whereas  in  coho display  the  Coldwater  (April) and fall stronger  by  movements Fyke  net catches,  spring  River  coho  (November).  downstream  between  current  (May)  as  f r y move Laboratory responses  98  than  similar  sized  resident  fry.  movement observed is not solely due  5) There  are  resident River. fry  no  differences  subyearling,  wild  in  This to  the  coho  argues  the  downstream  displacement.  ontogeny  from  that  of  current  Rosewall Creek  and  response the  in  Coldwater  Both populations exhibit downstream responses as recently emerged  during  May  and  June  and  as  yearlings  in A p r i l .  Two  year  old  Coldwater River coho also show downstream responses in the spring.  6) Under  diurnal  similar  among  Rheotaxis fall.  illumination conditions, laboratory  reared  coho  seasonal stocks  current  and  incubation  becomes progressively more positive from  Daytime  current  January-February,  responses  after  which  then  there  remain  is a  responses  treatments.  post-emergence  relatively  decrease  in  are  until  constant response  until which  reaches negative rheotaxis in April-May.  7) There  are  responses  significant between  differences in the  coastal and  interior  ontogeny  laboratory  between incubation treatments within stocks. River  coho  until and  generally  February. reaches  strong  display a  holding  Progressively stronger  a maximum in April-May.  negative  rheotaxis  in November  of  nocturnal  reared  coho,  Rosewall Creek-Big  response  under  negative  rheotaxis  Coldwater and  River  maintain  this  dark  current but  not  Qualicum conditions  then  occurs,  coho shift  to a  response  until  spring.  8) There are  no  differences in the  ontogeny of salinity preference  resident subyearling, wild coho stocks.  Generally,  resident and  between migrant  99  coho from both (0-8  ppt  Rosewall Creek and  seawater) salinities  however, when subjected both  stocks  and  the Coldwater River prefer  throughout  to a 4-24  Coldwater  River  ppt  the  year.  During  hypotonic April-May,  gradient, subyearling coho from  yearlings prefer isotonic to  hypertonic  salinities (12-16 ppt).  9) There  are  coastal  differences in  and  incubation  interior treatments  the  ontogeny  of  reared  coho  laboratory within  stocks.  In  a  Rosewall Creek coho generally prefer salinities the year. coho  shift  Coldwater salinity  When placed in a 4-24 to River  a  preference coho from  preference  from  ppt  for  both  salinity stocks, 0-20 up  ppt  but  not  between  seawater  gradient  gradient, however, Rosewall Creek  8-16  ppt  seawater  in  March-April.  exhibit a shift in  to isotonic or hypertonic  both gradients in November-December.  between  to isotonic throughout  incubation treatments  hypotonic  preference  salinities in  100  LITERATURE  CITED  Allen, I.R.H., and J.A. Ritter. 1967. Salmonid terminology, Part I; A revised terminology list for Atlantic salmon (Salmo salar). J . Conseil. 37: 293-296. Allendorf, F.W., and F.M. 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Press, Corvallis, Oreg., 331 p. Vanstone, W.E., and J.R. Markert. 1968. Some morphological and biochemical changes in coho salmon (Oncorhynchus kisutch) during parr-smolt transformation. J . Fish. Res. Board Can. 25: 2403-2418. Wagner, H.H., F.P. Conte, and J.L. Fessler. 1969. Development of osmotic and ionic regulation i n two races of Chinook salmon, Oncorhynchus tshawytscha. Comp. Biochem. Physiol. 29: 325-341. Waldichuk, M. 1952. Oceanography of the Strait of Georgia, 1. salinity distribution. Fish. Res. Board Can. Prog. Rep. Pac. 93: 26-29. Wedemeyer, G.A., R.L. Saunders, and W.C. Clarke. 1980. Environmental factors affecting smoltification and early marine survival of anadromous salmonids. N.O.A.A., Mar. Fish. Rev. 42(6): 1-14. Wehrhahn, C.F., and R. Powell. 1987. Electrophoretic variation, regional differences and gene flow in the coho salmon (Oncorhynchus kisutch) of southern British Columbia. Can. J . Fish. Aquat. S c i . 44: in press. Whelen, M.A., and D.B. Lister. 1985. CN Twin Track Project, Environmental Design Program: Juvenile Salmonid Overwintering Study, North Thompson River, 1985. prepared by D.B. Lister and Associates L t d . for CN Rail, Edmonton, 21 p. Whelen, M.A., and T . L . Slaney. 1986. Late winter sampling of juvenile salmonids in the Fraser River, prepared by Aquatic Resources Limited for Dept. Fish. Oceans, Vancouver, 17 p. plus appendices. Whelen, M.A., J.R. Arthur, W.R. Olmsted, and J.D. Morgan. 1983. 1982 studies of spawning coho salmon (Oncorhynchus kisutch) in tributaries of the south and mainstem Thompson Rivers, B.C. prepared by E.V.S. Consultants L t d . for Dept. Fish. Oceans, Vancouver, 100 p. Wightman, J.C. 1979. Fish production characteristics of the Coldwater River drainage with reference to construction of the Hope-Merritt highway and enhancement opportunities under the Salmonid Enhancement Program (S.E.P.). unpublished report of Fish. Hab. Imp. S e c , Fish Wildl. Br., Min. Env., Victoria, 107 p. Williams, I.V. 1969. Implications of water quality and salinity in the survival of Fraser River sockeye smolts. Internat. Pacific Salmon Fish. Comm. Progr. Rep. 22, 46 p. Zaugg, W.S., and L.R. McLain. 1970. Adenosine triphosphatase activity in gills of salmonids: seasonal variation and saltwater influence on coho salmon, Oncorhynchus kisutch. Comp. Biochem. Physiol. 35B: 587-596.  112  Zaugg, W.S., and L.R. McLain. 1972. Changes in gill adenosine triphosphatase activity associated with parr-smolt transformation in steelhead, coho and spring chinook salmon. J. Fish. Res. Board Can. 29: 167-171. Zaugg, W.S., and L.R. McLain. 1976. Influence of water temperature on gill sodium, potassium-stimulated ATPase activity in juvenile coho salmon (Oncorhynchus kisutch). Comp. Biochem. Physiol. 54A: 419-421.  113  APPENDIX 1 COMMON AND SCIENTIFIC NAMES OF FISH SPECIES FOUND IN THE STUDY STREAMS.  Common Name  S c i e n t i f i c Name  coho salmon chlnook salmon chum salmon  Oncorhynchus kisutch (Walbaum) 0. tshawytscha (Walbaum) 0. keta (Walbaum)  kokanee/sockeye salmon steel head/rain bow trout  0. nerka (Walbaum)  cutthroat trout Do 11y Varden char bu11 trout (char)  S. c l a r k l Richardson Salvellnus malma (Walbaum)  mountain whlteflsh coastrange sculpln prickly sculpln s1Imy scu1 pin threesplne stickleback redslde shiner longnose dace leopard dace longnose sucker lamprey  Salmo gairdneri Rlschardson  S . confluentus (Suckley) Prosoplum wl11lamsonl (Glrard) Cottus aleutlcus Gilbert C . asper Richardson C . cognatus Richardson Gasterosteus aculeatus Linnaeus Rlchardsonlus balteatus (Richardson) Rhlnlchthys cataractae (Valenciennes) R. falcatus (Elgenmann and Elgenmann) Catostomus catostomus (Forster) Entosphenus trldentatus (Gairdneri) Lampetra spp.  114  APPENDIX 2 ADULT COHO BROOD STOCK DATA FROM ROSEWALL CREEK AND THE COLDWATER RIVER.  Number <at Age Population  Sex  Sample  Standard Length (cm)  Weight (kg) 32  43  Male  2  59.8 ± 3.25  3.05 ± 0.550  2  0  Female  3  55.7 ± 0.33  2.07 ± 0.067  3  0  Total  5  57.3 ± 1.45  2.46 ± 0.299  5  0  Male  4  46.3 ± 1.70  1.13 ± 0.111  1  0  Female  8  50.2 ± 1.48  1.34 ± 0.127  4  1  12  48.9 ± 1.23  1.27 ± 0.095  5  1  a  Rosewa11 Creek  Coldwater River  Total  a - The age sample sizes for the Coldwater River stock are small due to resorption and regeneration problems. APPENDIX 3 EGG SIZE, INCUBATION TEMPERATURE AND INCUBATION SURVIVAL RATE BY POPULATION.  Population  Rosewa11 Creek  Coldwater River  Egg Vo1ume (ml) (n=30)  0.33 ± 0.007  0.15 ± 0.003  Natural Incubation Temperature ( ° C )  4.6 ± 0.13 (n=212)  2.7 + 0.17  Laboratory 1ncubatlon Temperature ( ° C )  1ncubatlon Survival Rate (?)  2.9 ± 0.15 (n=183)  76.3  6.6 ± 0.06 (n=94)  68.0  2.9 ± 0.19  82.3  (n=183)  (n=241) 5.9 ± 0.02 (n=95)  82.9  115  APPENDIX 4 FRY EMERGENCE DATES, EMERGENT RATES, EMERGENT NUMBERS AND LENGTH AND WEIGHT DATA.  Fork Length (mm) (n=30)  Weight  851  34.4 ± 0.18  0.30 ± 0.006  54.1 (n=6) 38.2 - 65.2  1,703  33.1 ± 0.21  0.28 ± 0.007  66.1  1,184  30.4 ± 0.22  0.18 ± 0.006  2,287  30.0 ± 1.05  0.22 ± 0.006  Emergence 1ncubatlon Emergent Date Rate (?) Popu1 atIon Treatment (1982) (Mean & range) <°C) 2  July 1  92.5  Total Emergent Number  (n=3)  (g) (n=30)  91.4 - 94.0  Rosewa11 Creek 6  March 19  2  June 23  (n=3)  43.1 - 78.1  Coldwater Rl ver March 10  6  23.4  (n=6)  11.9 - 40.6  APPENDIX 5 LABORATORY REARING CONDITIONS.  Population  1ncubatlon D1 sso1ved Treatment Oxygen Range (°C) (mg.L 8 °C & % saturation)  pH  Container  -1  2 Rosewa11 Creek (Big Qua 11 cum River)  6  2 Co 1dwater River  7.6 6 14.4 11.4 6 6.5 (75*-94?)  6.27 ± 0.053 (n=17)  8.3 @ 9.2 11.6 6 6.6 (73*-96*)  6.30 ± 0.031 (n=28)  7.8 @ 14.4 11.4 g 8.2  6.30 ± 0.048  6.2 @ 14.4 11.8 6 6.6 (61*-96jf)  Rearl ng DensItles Range (no.L ) - 1  Trough  7.9 - 9.0  Tank  0.7 -  Trough  16.0-17.9  Tank  1.0 - 2.2  Trough  10.9-12.5  Tank  0.9 - 1.5  Trough  21.9-24.0  Tank  1.0 - 2.6  1.1  (n=17)  (76.55f-96.8iO 6  Rear 1ng  6.27 ± 0.033 (n=30)  116  APPENDIX 6 GEOMETRIC FUNCTIONAL REGRESSIONS OF STANDARD LENGTH ON FORK LENGTH AND TOTAL LENGTH ON FORK LENGTH FOR WILD AND LABORATORY RAISED COHO JUVENILES. Total  Length on Fork Length. Correlation  Sample Size (n)  Slope (v)  409  0.930  -2.09  0.99961  RosewaII C r , , 6°C incubation.  640  0.934  -2.176  0.99987  Rosewa11 C r . , 2°C incubation.  530  0.924  -1.822  0.9998  Coldwater R., Wild coho.  725  0.930  -1.987  0.99915  Coldwater R., 6°C Incubation.  700  0.933  -1.881  0.99989  Coldwater R., 2°C Incubation.  534  0.927  -1.689  0.99983  Popu1 at Ion  Rosewal1 C r , ,  Y-lntercept (a')  Coeff iclent (r)  Wild coho. a  Standard Length on Fork Length. Sample Size (n)  S1 ope (v)  Y - l ntercept (a')  Correlation Coef f Icient (r)  409  1.128  -2.241  0.99956  RosewaII C r , , 6°C Incubation.  640  1.099  -1.241  0.99981  Rosewal1 C r . , 2°C Incubation.  530  1.101  -1.429  0.9977  CoIdwater R.,  617  1.118  -1.674  0.99963  Coldwater R., 6°C incubation.  670  1.099  -1.043  0.9998  Co 1dwater R., 2°C Incubation.  534  1.103  -1.402  0.9998  Popu1 at Ion  Rosewal1 C r . , Wild coho. a  Wild coho.  a -  Includes Big Oualicum River coho.  117  APPENDIX  7  THE OBSERVED FLOW REGIME IN THE CURRENT RESPONSE CHANNELS OVER THE 12 MONTH STUDY PERIOD.  Riffle  Flow Velocity (cm.s"') by Channel Number (n=12). 1  2  3  Upstream 1  10.7 ± 8.38  12.2 ± 0.68  11.0 ± 0.49  2  10.7 ± 0.34  11.3 ± 0.26  10.8 ± 0.27  3  10.4 ± 0.30  11.5 ± 0.34  11.1 ± 0.30  4  10.3 ± 0.25  10.8 ±  0.21  10.7 ± 0.29  5  10.6 ± 0.09  11.4 ± 0.37  11.0 ± 0.39  6  10.4 ± 0.24  10.9 ± 0.26  10.6 ± 0.33  7  10.5 ±  0.21  11.0 ± 0.27  10.3 ± 0.25  8  10.4 ± 0.23  10.9 ± 0.24  10.6 ± 0.26  9  10.2 ± 0.22  10.1 ± 0.27  10.3 ±  0.21  10  a  9.7 ± 0.17  10.1 ± 0.26  10.2 ± 0.23  11  a  10.0 ± 0.24  9.9 ± 0.19  9.7 ± 0.16  12  10.2 ± 0.22  9.6 ± 0.14  10.4 ± 0.32  13  9.5 ± 0.14  10.3 ± 0.29  10.1 ± 0.29  14  10.1 ± 0.23  10.8 ± 0.38  10.1 ± 0.25  15  9.5 ± 0.22  16  10.1 ± 0.15  10.0 ± 0.26  9.7 ± 0.29  17  10.2 ± 0.24  11.3 ± 0.40  10.1 ± 0.19  18  9.8 ± 0.20  11.0 ± 0.33  10.0 ±  0.21  19  10.0 ± 0.28  11.4 ± 0.45  10.3 ±  0.31  10.0 ± 0.17  11.2 ± 0.59  10.0 ± 0.35  20 Downstream  a - The location of the r i f f l e s  1 1.4 ±  0.51  9.7 ± 0.20  Immediately upstream and  downstream of the release chamber.  118  APPENDIX 8  DESIGN AND  In  C A L I B R A T I O N OF  most of the experiments  followed  those  Experimental experiments  EXPERIMENTS  discussed below, the preparatory  described in this Techniques.  The  thesis  under  general  similar  results  and  are given in the main text of the thesis  Calibration of Experiments).  The  headings  procedures in Methods,  disccussion  of  (Methods, Design  these and  full results for these experiments are given  here, along with descriptions of specific treatments and variations in handling procedures.  Plasma Sodium Regulatory Ability  Timing of Sample Collection  To  examine  seawater ability  the  trend  challenge test,  after  24  both seawater These  samples  plasma  sodium  hours  and  in plasma  as well as  of treatment,  sodium  undergoing  subsamples of 5 coho were taken  freshwater solutions at 0, 2, 4, 8, 12, 24, and  were  anaesthetised and  analyses.  depicted in Figure 1.  Coldwater  a caudal River The  blood  sample  hours  the  subyearlings and  is an  from  48 hours.  collected for Big  Qualicum  results of these collections are  Comparisons between sodium levels at 24 and  1) indicate that 24  sample collection.  in fish  possible variations in sodium regulatory  River yearlings were tested separately.  (Table  levels  48 hours  acceptable preacclimation interval for  119a  Appendix 8, Figure 1.  Seawater challenge tests exposure time experiments  Error bars represent 95% confidence limits.  119  Coldwater  River,  Age 0+ W i l d  Coho  O O  m  Seawater c h a l l e n g e Freshwater  test  control  o in ru  +  to  CD E CO CD  o o OJ  o in  -EDE-ffl  m  jg. - - f f i - - -gj  o o 10  20  30  40  50  Time (hours)  Coldwater  Age 1+ W i l d  River,  Coho  O  o m  Seawater c h a l l e n g e Freshwater  E CD  control  o in ru O O OJ  z  CD E 0) CD  test  O  in  ^-HJ-^ — ©  *  9r  -£  9  <  o o 10  20  30  Time (hours)  40  50  120  APPENDIX 8: TABLE 1 SEAWATER CHALLENGE TEST TIMING EXPERIMENTS; COMPARISONS BETWEEN PLASMA SODIUM CONCENTRATIONS COLLECTED 24 AND 48 HOURS AFTER EXPERIMENT INITIATION.  Population and Stage  Big Qual(cum River, year 11ngs (smolt s i z e ) .  Fork Length (mm)  Test or Control  129.5 ± 0.99  Control  (n=86)  Time (hr)  Plasma INa l (mM.L ) +  -1  24  149.1 ± 1.20 (n=5)  48  151.4 ± 1.28  s val ue +  1.282  (0 ppt)  p>0.05  (n=5) 24  179.2 ± 4.06 (n=5)  48  178.4 + 4.50  Test (30 ppt)  0.125 p»0.05  (n=5)  Co 1dwater River, subyear11ng fry.  60.6 ± 1.13 (n=67)  24  144.7 ± 2.30 (n=5)  48  148.9 ± 2.24 (n=5)  24  220.3 ± 5.99 (n=5)  48  213.1 ± 4.19 (n=5)  Control (0 ppt)  Test (30 ppt)  1.327 p>0.05  0.844 p»0.05  121  Dilution and Range Setting Effects on Photometric Readings  Only River  large,  smolt  size,  Hatchery, were used  changes  yearling  coho,  collected  in this experiment.  in standard and sample  from  the Big Qualicum  To examine the effects of  dilutions, and in photometer  range  settings,  plasma samples were collected from fish held in seawater or freshwater for 24 hours and were divided  between four treatments.  The treatments were:  1) calibration standard dilution - 1:200, sample dilution - 1:200, photometer range setting - 0-140, multiplicative factor - none. 2) calibration standard dilution - 1:200, sample dilution - 1:400, photometer range setting - 0-140, multiplicative factor - 2X. 3) calibration standard dilution - 1:400, sample dilution - 1:400, photometer range setting - 0-70, multiplicative factor - 2X. 4) calibration standard dilution - 1:400, sample dilution - 1:400, photometer range setting - 0-140, multiplicative factor - none.  Treatment (Anon. within  1 was  the combination recommended  1977) and served as a control. freshwater and  seawater  groups  by the operations manual  Mean sodium using  values were compared  one-way  ANOVA  (Table 2).  Treatments were grouped  using the T-method multiple range test.  Dunnett's  pairwise  was  with the  control  comparison (Table 2).  test  also  used  to group  the data  sets  Treatment means were homogenous, indicating that any of  the above treatments would be acceptable.  122  APPENDIX 8: TABLE 2 SEAWATER CHALLENGE TEST DILUTION EFFECTS; COMPARISONS BETWEEN PLASMA SODIUM CONCENTRATIONS IN SAMPLES TREATED TO DIFFERENT DILUTIONS AND PHOTOMETER RANGE SETTINGS.  Fork  Sample Test Conditions  Control  Size (n)  34  Weight (g)  23.26 ± 0.735  Length (mm)  131.2 ± 1.54  (0 ppt seawater)  Test (29 ppt seawater)  Multiple Trtmt Type  Plasma INa l (mM.L )  1  160.5 ± 0.83  2  158.3 ± 1.04  3  Range  +  -1  val ue  1.083  Com par 1 son'  (1,2,3,4)  p>0.05  34  24.03 ± 1.191  133.2 ± 9.70  3  159.0 ± 0.94  4  158.7 ± 0.92  1  184.2 ± 1.49  2  181.8 ± 1.61  3  181.3 ± 1.57  4  181.6 ± 1.53  All coho used In t h i s experiment were from the Big Qualicum Rlve>-. a - Treatment (Trtmt) types. For a d e s c r i p t i o n , see the t e x t , b - Both the T-method and Dunnett's palrwlse comparison t e s t (using treatment type 1 as the control) gave the same r e s u l t s .  0.715 p>0.05  (1,2,3,4)  5  123  Handling and Confinement Effects  Big  Qualicum River yearlings were used in this experiment.  handling  and confnement  effects,  samples  of coho  received  To test for  three  different  treatments: 1) coho were not weighed during the test, 2) coho were weighed the tests, and  prior  before  to the test  the test  and were  not confined  but were not confined  during  3) coho were weighed before the test and were confined during the test.  These  treatments  Treatment 1 served The with  were  carried  coho  used  treatment 3.  fresh  and  as a control and the coho were weighed  other two treatments involved 20  out in both  in treatments  pretest weighing. 1 and  2,  and  salt  after the test.  Sample sizes 30  water.  yearlings  varied, used in  More fish were included in treatment 3 because it was possible  that the extra handling might result in mortality.  Because  different  samples  were  used  in each  treatment,  differences  between mean weights and lengths were examined within fresh and salt water groups with one-way ANOVA homogeneity homogeneity,  in weight fish  sodium values.  (Table 3).  and length  Multiple comparisons confirmed the  of sample  size was not considered  fish  (Table  3).  Given  this  further as a factor in the plasma  124  APPENDIX 8: TABLE 3 SEAWATER CHALLENGE TEST HANDLING EFFECTS; COMPARISONS OF WEIGHT, LENGTH AND PLASMA SODIUM CONCENTRATIONS IN SAMPLES TREATED TO DIFFERENT DEGREES OF HANDLING AND CONFINEMENT.  Treatment Type Test CondItlons  Measurement 2  16.33 ± 0.901 (n=20)  16.68 ± 0.868  seawater)  Fork Length (mm)  117.3 ± 2.44  118.1 ± 1.78  Plasma (mM N a . L )  155.6 ± 0.99 (n=20)  146.4 ± 2.06 (n=19)  147.1 + 0.99 (n=30)  15.24 ± 0.944 (n=20)  17.98 ± 0.870 (n=20)  16.27 + 1.008 (n=18)  2.255 p>0.05  (1,2,3)  Fork Length (mm)  115.4 + 2.36 (n=20)  120.7 ± 2.04 (n=20)  1 16.4 ± 2.33 (n=18)  9.601 p>0.05  (1,2,3)  Plasma (mM N a . L )  177.1 ± 0.93 (n=20)  172.2 + 1.14 (n=20)  176.9 ± 1.54  5.437 p<0.01  (1,3) (2)  (g)  +  _ 1  Weight Test (29 ppt seawater)  (g)  +  _ 1  (n=20)  (n=19)  (n=19)  3 18.5 ± 0.904 (n=30) 120.3 ± 1.79 (n=30)  (n=18)  va 1 ue  Multiple Range Com par 1 son'  1 Weight  Control (0 ppt  3  1.781 p>0.05  (1,2,3)  0.608  (1,2,3)  p>0.05 -c-  (1) (2,3)  All coho used In t h i s experiment were from the Big Qualicum River, a - Treatment types are described In the t e x t . b - Tukey-Kramer's t e s t was used among homoscedastIc freshwater control samples. The T ' - t e s t was used for homoscedastlc test samples. The Games and Howel I method was used for heteroscedastIc control plasma sodium concentrations. c - Sample variances heteroscedastic.  5  125  Differences in plasma sodium with  a one-way  water of  ANOVA  plasma sodium  treatment  (Table  sample  means  3).  and  was  Handling  values in seawater treated coho were tested  a T  comparison  1  test  (Table  3).  variances were heteroscedastic, the examined  and  using  confinement  the  Games  produced  and  Since fresh homogeneity  Howell  significant  method  differences  between treatment means, with control mean values the highest.  Current  Response  Timing of Distribution Collection  Three wild  test  groups  Rosewall  Creek  Standard  test  were used and  procedures  were taken at 0.5  hour  in this experiment; wild  laboratory were  used  raised except  Chef that  intervals over a 4 hour  variation in response distributions over time.  Creek  Coldwater  River,  yearling  coho.  distribution  observations  period to examine possible  Distributions under light were  observed from behind a black plastic screen, while distributions in the dark were checked  with a penlight.  this experiment averaged 9.03 from  8.8°C  to 9.6°C,  temperatures.  conditions.  replicates The  -1  flow rate at the release points  ± 0.230 c m . s  deviated  Dissolved oxygen  at 10°C to 11.2 m g . L  Three  and  The  no  -1  (n=18).  more than  Temperatures  0.9°C  from  the  during ranged rearing  levels were relatively stable at 10.8 mg.L~l  at 10.2°C (95-96% saturation).  of  each  resulting  group  were  distributions  treatments for each time interval.  The  tested were  under  pooled  light  within  and  dark  illumination  proportion of fish in each group at  the point of release and the ends of the channels at each observation interval  126  were then angular transformed, and  the mean inverse was  plotted  to depict  movement timing (Figures 2 and 3).  As discussed in the Methods section of this thesis, most of the movement occurred during the first 2.0 coho  hours.  Among groups, the larger Chef Creek  (Table 4) responded more quickly  interior  Coldwater  dark.  Homogeneity  distributions  River  within  fish  showed  in responses populations  under light conditions, whereas the  a faster  and  greater  over  time were  and  illumination  nonparametric multiple comparison by STP  response in the  examined  by  conditions  test (Table 5).  grouping using  a  Distributions were  homogeneous after the first hour of movement.  Salinity Preference  Test Sample Size, Exploration Time and Gradient Stability  To determine an adequate sample size and exploration period, groups of 1 to 5 coho were observed as they explored the gradient channels.  These tests  were carried out in freshwater. Groups were released in the channels after a 0.5  hour acclimation period, and  individual was for of  the position of each  noted and explorations to the end of each channel documented  each 0.5 hour interval. three  over a 4 hour period  different  For each group size, three replicates from each  populations  River) were completed  and  (Rosewall Creek,  the results  pooled  Chef  Creek  (Table 6).  and  Coldwater  Based  on these  results, a standard exploration period of 2.0 hours for a group of 5 coho selected.  was  127a  Appendix 8, Figure 2.  Current  response test timing experiment; light conditions.  Each point represents the mean inverse of the transformed proportion observed (n=3).  angular  127  Coho R e m a i n i n g a t R e l e a s e  Point  n  --o- • -  R o s e w a l l Creek coho  • • X-•  Chef Creek coho  •\  A-  C o l d w a t e r R i v e r coho  •\  • \\ • \\  •V • V X . " X- . .  1  I  0  1  X • " • X- • • • X- • • 1 2 Time  Coho M o v i n g  X 1 A  3  (hours)  t o C h a n n e l Ends  R o s e w a l l Creek coho • •X •  -  Chef Creek coho  X  C o l d w a t e r R i v e r coho  -  .x-'  . x  ••  X  •• *  x  —A-  -  GJQ.  0  1  Q  -""  Qf"  2 Time  &——  (hours)  i  i  3  4  128a  Appendix 8, Figure 3.  Current  response test timing experiment; dark conditions.  Each point represents the mean inverse of the transformed proportion observed (n=3).  angular  128  Coho R e m a i n i n g a t R e l e a s e P o i n t  \\ \\ U \* \ \ \* \* \ \"  Rosewall Creek Coho  • •X •  Chef Creek Coho  A —  Coldwater R i v e r Coho  \ V  \  \ '  X • •  "  0  1  2  l*r  n  9  i*i—  3  Time (hours)  Coho M o v i n g t o C h a n n e l E n d s  R o s e w a l l Creek Coho  •XA  Chef Creek Coho Coldwater R i v e r Coho  Time (hours)  - LiA  i  4  129  APPENDIX 8: TABLE 4 CURRENT RESPONSE TESTS - TIMING OF DISTRIBUTION COLLECTION COMPARISONS OF WEIGHT AND LENGTH OF TEST GROUPS.  Population  Rosewa11 Creek,  Sample Size (n)  Weight (g)  Fork Length (mm)  60  12.27 ± 0.361  107.8 ± 1.05  Multiple Range Com par 1 son  9  Wild coho Weight Chef Creek, Laboratory reared coho  (1) 60  20.36 ± 0.526  (2)  Length (1)  Co 1dwater River, Wild coho  (3)  125.4 ± 0.96  120  2.07 + 0.070  (2)  (3)  59.5 ± 0.61  a - Games and Howell method for heteroscedastlc group comparisons used APPENDIX 8: TABLE 5 CURRENT RESPONSE TESTS - TIMING OF DISTRIBUTION COLLECTION MULTIPLE COMPARISON GROUPINGS OVER TIME.  1 1 1 urn 1 nation Popu1 at Ion Conditions  Light (Day time)  Multiple Comparison Groupings of Half Hourly D i s t r i b u t i o n s  9  Rosewa11 Creek  (0.5,1.0,1.5,2.0,2.5,3.0,3.5,4.0)  Chef  (0.5,1.0,1.5,2.0,2.5,3.0,3.5,4.0)  Creek  Dark (Night time)  Coldwater River  (0.5,1.0,1.5,2.0,2.5,3.0,3.5,4.0)  Rosewa11  (0.5,1.0,1.5,2.0)  Creek  (1.0,1.5,2.0,2.5,3.0,3.5) (1.5,2.0,2.5,3.0,3.5,4.0)  Chef Creek  (0.5,1.0,1.5,2.0,2.5,3.0,3.5) (1.0,1.5,2.0,2.5,3.0,3.5,4.0)  Co 1dwater River  (0.5,1.0,1.5,2.0,2.5,3.0,3.5,4.0)  a - Multiple comparison groupings completed using the nonparametric STP method.  130  APPENDIX 8: TABLE 6 SALINITY PREFERENCE TESTS; TIME REQUIRED FOR COHO OF DIFFERENT GROUP SIZES TO EXPLORE A MODIFIED STAALAND CHANNEL.  Group Size  Proportion Reach 1ng the Channel End  1  Test  Time Required to Reach the End of the Channel (hr) Mode  Range  0.333  2.0  2.0 - 2.0  2  0.167  4.0  4.0 - 4.0  3  0.61  2.0  1.0 - 3.5  4  0.792  1.0  0.5 - 3.5  5  0.61  2.0  0.5 - 4.0  Three replicates of three populations of each group size were combined to give the r e s u l t s . Weights and Fork lengths of the population samples used were: - RosewalI Creek - n=40, Weight - 8.53 ± 0.241 g , Fork Length - 91.8 ± 0.94 mm. - Chef Creek - n=30. Weight - 8.74 ± 0.433 g, Fork Length - 92.9 ± 1.55 mm. - Coldwater River - n=42, Weight - 7.51 ± 0.364 g , Fork Length - 91.6 ± 1.25 mm.  131  To  check  gradient  stability,  separate gradients of 0 to 20 ppt and 4 to  24 ppt seawater were established in the four channels. left  over  night  and  then  groups  released into each channel. The  of 5 large  The channels were  Coldwater  River  coho  were  Size data for these fish are given in Table 6.  fish were left for 24 hours, and then water samples were collected and  tested  for salinity.  occurred  The  results  indicate  that  little  gradient  change had  (Table 7).  Timing of Distribution Observations  These salinity  experiments were conducted preference  acclimation freshwater.  biasing  observations the  to determine the period  could  results.  The  Coho groups of 5 fish  be  collected  experiments  during  which  and  pooled  without  were  carried  out in  were released into each channel after a  standard holding period and distribution observations were collected every 15 minutes  for 4 hours.  population, The  Four  were collected  replicates,  for Coldwater  or  16 observation  River  wild  sets  for each  f r y and Rosewall f r y .  data were then pooled and distributions over time compared and grouped  using  nonparametric comparisons  by STP  analyses (Table 8).  Distributions  between 2.0 and 4.0 hours were deemed to be homogeneous and suitable for pooling.  Possible Biases Caused by Preference Channel Design  Figure 4 shows the tendency  for coho searching control gradients  (fresh  water or 4 ppt seawater) to localize their movements at the release site or the end of each channel.  132  APPENDIX 8: TABLE 7 SALINITY PREFERENCE TESTS; SALINITY GRADIENT STABILITY.  4-24 ppt Seawater  0-20 ppt Seawater Grad1ent  Grad1ent  SalInlty  SalInlty  SalInlty  SalInlty  before  a f t e r the  before  a f t e r the  the Test  Test (ppt)  the Test  Test (ppt)  (ppt)  (n=4)  (ppt)  (n=4)  0  a  b  0  a  b  4.6  4.2 ± 0.041  4.5  4.0 ± 0.041  8.6  8.2 ± 0.063  7.8  8.1 ± 0.041  12.3  12.1 ± 0.065  12.0  12.0 ± 0.085  16.9  16.1 ± 0.108  15.7  15.9 ± 0.065  20.6  20.4 ± 0.091  20.1  20.1 ± 0.058  24.6  24.5 ± 0.096  A l l coho used In t h i s experiment were from the Coldwater River. For size data, see Appendix 8, Table 6. a - S a l i n i t y measured by hydrometer. b - S a l i n i t y measured by conductivity meter.  133  APPENDIX 8: TABLE 8 SALINITY PREFERENCE TEST - TIMING OF DISTRIBUTION COLLECTION; MULTIPLE COMPARISON GROUPINGS OVER TIME.  Multiple Comparison Groupings of  Popu1 at Ion  Quarter Hourly D i s t r i b u t i o n s Rosewa11 Creek, Wild coho.  Coldwater River, Wild coho.  9  (0.25,0.5) (0.75, 1.0,1.25, 1.5, 1.75,2.0,2.25,2.5,2.75,3.0, 3.25,3.5,3.75,4.0) (0.25,0.5) (0.5,0.75) (0.75, 1.0,1.25,3.75,4.0) (1.0,1.25, 1.5, 1.75,2.0,2.25,2.5,3.25,3.5,3.75,4.0) (1.25,1.5, 1.75,2.0,2.25,2.5,3.0,3.25,3.5,3.75,4.0) (1.5,1.75,2.0,2.25,2.5,2.75,3.0,3.25,3.5,3.75,4.0)  a - Multiple comparison groupings completed using the nonparametric STP method. Weight and fork lengths of the population samples used were: - Rosewal I Creek - n=42. Weight - 12.26 ± 0.432 g . Fork Length - 107.8 ± 1.28 mm. - Coldwater River - n=54, Weight - 9.42 ± 0.311 g . Fork Length - 96.4 ± 1.07 mm.  134a  Appendix 8, Figure 4 .  Control distributions in salinity preference channels.  Histogram bars represent the mean inverse of square root tranformed counts. 95% confidence limits are also given.  134  Rosewall  C r e e k Coho  YZZZA  Freshwater  Control  A ppt Seawater C o n t r o l  z  I Channel  Location  Coldwater River  1  7  YZZZA  Freshwater  Control  A ppt Seawater C o n t r o l  ^  Channel  Coho  Location  135  Potential Effects of Size and Growth  To  determine  experimental (Table 9, (Tables  the  degree  groups, linear  Figures  10 and  in  size  and  growth  among  w  7) were compared  m  using analyses  of  covariance  In addition, to examine whether size differences could  contribute to migratory was  differences  regressions of logio( eight) against logio(fl e)  5, 6 and  11).  of  tendencies, the weight of wild capture migratory coho  compared to the weight of resident f r y from the same population collected  at approximately  the  same time  (Table  12).  Wild population and  laboratory  group growth trends differed significantly within experimental series, however the  trends  among  laboratory  raised  between wild populations  (Table  stocks  showed  and  significantly  treatments different  over  time  groups  10).  were  much  more  similar  than  Comparisons of growth trends within  that  experimental  for wild  and  similar for 6°C incubation groups (Table 11).  2°C  series  samples  incubation  Migrant and  groups  were but  resident Coldwater  coho f r y did not differ in size within season, however Rosewall Creek spring, resident  fry  (Table 12).  were  significantly  larger  than  corresponding  migrant  fry  136  APPENDIX 8: TABLE 9 REGRESSION SLOPES AND Y-l NTERCEPTS FOR STUDY GROUP GROWTH TRENDS; (Log (we!ght) = a + b Log (tlme)) 10  10  Regress Ion Population  1ncubatlon  Study  Sample  Treatment  Test  Size  Rosewa11 Creek Big  Wild coho  QualIcum River.  Lab raised 2°C incub.  Lab raised 6°C incub.  Co 1dwater  Correlation Slope  Coeff icient  <n)  ( b)  Y-lntercept (a)  1 4  269 409  1.704 1.871  -3.782 -4.162  0.864 0.877  1 2 3  300 400 400  3.171 3.328 3.024  -7.507 -7.925 -7.140  0. 940 0.947 0.940 0.975 0.968 0.969  3  (r)  1  413  2.186  2  460  2.147  3  450  2.137  -4.695 -4.600 -4.572  Wild coho  1 4  395 660  1.880 1.765  -4.599 -4.336  0.865 0.834  Lab raised 6°C Incub.  1 2 3  300 424 424  3.183 3.740 3.701  -7.673 -9.105 -8.997  0. 935 0.964 0.961  Lab raised 2°C Incub.  1 2 3  420 530 519  2.647 2.616 2.651  -2.647 -2.616 -5.889  0.981 0.980 0.976  River.  a - Study test -  1. 2. 3. 4.  Seawater Challenge T e s t . Current Response Test. S a l i n i t y Preference T e s t . Both Behavioural Response Tests Combined (2 & 3 ) .  137a  Appendix  8, Figure 5.  Growth regressions for wild stocks; login (weight) vs loginUime)  Units of time are consecutively numbered (1-730) during 1982-83.  days  137  Seawater Challenge  T e s t Sample  in  i  l  i  I  I  I  I  L  2.0  2.2  2.4  2.6  2.8  3.0  Log  1 0  (Time  Total  i  i  i  i  2.0  2.2 Log  1 0  (Time  (numbered days. 1982-83))  W i l d Coho S a m p l e  1  1  1  2.4  2.6  2.8  (numbered days. 1982-83))  1  3.0  138a  Appendix 8, Figure 6.  Growth regressions for 6°C incubated laboratory coho stocks; logio( eight) vs logio(time) w  Units of time are consecutively numbered days (1-730) during 1982-83.  138  Seawater C h a l l e n g e Test  2.0  2.4  2.2  Log  )0  2.6  2.8  2.2  Log  )0  2.4 2.6 (Time (numbered days,  Salinity  2.0  Log  )0  2.6  (Time (numbered days.  Sample  2.6  3.0  1982-83))  Preference Test  2.4  2.2  3.0  (Time (numbered days, 19B2-B3))  C u r r e n t Response T e s t  2.0  Sample  Sample  2.8  1982-83))  3.0  139a  Appendix 8, Figure 7.  Growth regressions for 2°C incubated laboratory coho stocks; login (weight) vs login (time)  Units of time are consecutively numbered days (1-730) during 1982-83.  139  Seawater C h a l l e n g e Test  C u r r e n t Response Test  Sample  Sample  3.0  Salinity  2.0  2.2 Log  Preference Test  2.4 ) 0  2.6  (Time (numbered days,  Sample  2.6 1982-83))  3.0  140  APPENDIX 8: TABLE 10 ANALYSIS OF COVARIANCE COMPARISONS OF GROWTH REGRESSIONS FOR STUDY GROUPS.  Study Test  1ncubatlon Treatment Wild coho  Seawater Challenge Test  Lab raised Incub.  Lab raised 2°C  Incub.  Lab raised Response Test  SalInlty Preference Test  < s> F  Equa11ty of Adjusted Means ( F ) s  4.517 p=0.034  6°C  Current  Equality of SI opes  6°C  Incub.  167.85 p<0.001 0.017  148.011  p>0.05  p<0.001  187.76 p<0.001  Lab raised 2°C Incub.  29.832  Lab raised  193.872  6°C  Incub.  p<0.001  p< 0.001  Lab raised 2°C Incub.  79.206  WlId coho  2.508 p>0.05  p<0.001  Both Behavioural Response Tests  895.947 p<0.001  141  APPENDIX 8: TABLE 11 ANALYSIS OF COVARIANCE COMPARISONS OF GROWTH REGRESSIONS WITHIN STOCKS AND TREATMENTS.  EqualIty of Population  1ncubatlon  SI opes  Treatment  (F )  Wild coho  4.079 p=0.044  s  Rosewa11 Creek (Big Qualleum River)  Lab raised 6°C  Incub.  Lab raised 2°C incub. Wild coho  3  Equa1ity of Adjusted Means ( F ) s  0.989  0.168  p>0.05  p>0.05  7.339 p< 0.001 2.595  11.2.14  p>0.05  p<0.001  Lab raised 6°C Incub.  0.603 p>0.05  0.629 p>0.05  Lab raised 2°C Incub.  25.791 p<0.001  Co 1dwater River  a - Includes Big Qualicum River coho.  142  APPENDIX 8: TABLE 12 COMPARISONS OF SIZE BETWEEN RESIDENT AND MIGRANT COHO SUBYEARLINGS.  Study Test  Date (1982-83)  Seawater Challenge Test  Dec. 3  Both  May 19  Population, Capture Type  Sample Size (n)  Weight (g)  Co 1dwater R., Resident coho  11  Co 1dwater R., Migrant coho  17  2.14 ± 0.255  RosewaII C r . , Resident coho  21  1.04 ± 0.085  RosewaII C r . , Migrant coho  46  0.34 ± 0.001  Coldwater R., Resident coho  12  0.24 ± 0.001  Coldwater R., Migrant coho  11  0.28 ± 0.001  Co 1dwater R., Resident coho  62  1.78 ± 1.148  Co 1dwater R., Migrant coho  33  +s val ue  Us va i ue  2.33 ± 0.335 0.407 p>0.05  966 p<0.05  Behavioural Response Tests May  May  9  4 .  Nov. 20  1.30 p>0.05  724 p>0.05 1.96 ± 0.493  143  APPENDIX 9 SALINITY PREFERENCE DISTRIBUTION MODES AND MANN-WHITNEY U TEST COMPARISONS BETWEEN TEST AND CONTROL DISTRIBUTIONS. Population & Treatment  Date  gradient, Age 0+ Residents,  Age 0+ Migrants.  Rosewal1 C r . , Wild coho, 4-24 ppt. gradient, Age 0+ Residents,  Age 0+ Migrants.  Rosewal1 C r . , 6°C incubation, 0-20 ppt. gradIent.  (day)  Mode 3  (ppt)  Va1ue  D  8  159  4  Aug. 18  230  0  15.356 *  Nov.  5  309  4  16.703 *  Feb. 10  406  12  9.858 *  Mar. 26  450  8  May  25  510  4  40.962 *  June  9  160  0  17.666 *  June  6  157  8  17.679 *  Aug. 16  228  4  4.359 »  Nov.  8  312  8  17.28  Feb.  8  404  4  17.563 *  Mar. 29  453  4  30.239 *  May  27  512  12  2.853 *  June 13  164  8  6.798 *  May  7  127  4  1.164 ns  May  31  151  0  June 25  176  4  July 25  206  4  13.70  Sept. 2  245  4  27.299 *  Nov. 12  316  4  14.831 *  Dec. 15  349  4  14.726 *  Jan. 10  375  4  26.011 *  June Rosewal1 C r . , Wild coho, 0-20 ppt.  Time  (1982-83)  5.96  *  1.014 ns  12.07  *  *  2.167 * *  a - Time ranges from 1-730 days which are equivalent to the calender dates January 1, 1982 to December 31, 1983. b - * - p<0.05, ns - p>0.05.  144  APPENDIX 9 (CONTINUED) SALINITY PREFERENCE DISTRIBUTION MODES AND MANN-WHITNEY U TEST COMPARISONS BETWEEN TEST AND CONTROL DISTRIBUTIONS. Population & Treatment  RosewaII C r . , 6°C Incubation, 0-20 ppt. grad1ent, (contlnued).  Rosewa11 C r . , 6°C Incubation, 4-24 ppt. gradient.  RosewaII C r . , 2°C Incubation, 0-20 ppt. grad1ent.  Date (1982-83)  Time (day)  Mode 3  (ppt)  Va1ue  b  Feb.  3  399  0  54.585 *  Mar.  4  428  4  17.395 *  Apr.  4  459  0  61.384 *  May  8  493  8  4.758 *  June 16  532  4  10.051 *  June  2  153  8  C  -c-  June 28  179  4  C  -c-  July 24  207  4  14.652 *  Sept. 5  248  8  42.606 *  Nov. 15  319  12  Dec. 21  355  4  25.410 *  Jan.  6  371  4  23.109 *  Feb.  7  403  8  41.804 *  Feb. 28  424  8  9.996 *  Apr. 17  472  16  4.946 *  May  3  488  12  13.576 *  June 22  538  4  0.342 ns  Aug.  221  4  5.887 *  Sept. 17  260  0  47.6  Oct. 20  293  4  36.238 *  Nov. 21  325  0  27.657 *  9  6.831  *  *  a - Time ranges from 1-730 days which are equivalent to the calender dates January 1, 1982 to December 31, 1983. b - * - p<0.05, ns - p>0.05. c - No control distributions were c o l l e c t e d . The modes given are for the test d i s t r i b u t i o n .  145  APPENDIX 9 (CONTINUED) SALINITY PREFERENCE DISTRIBUTION MODES AND MANN-WHITNEY U TEST COMPARISONS BETWEEN TEST AND CONTROL DISTRIBUTIONS.  Population & Treatment  Mode  Date (1982-83)  Time (day)  Dec. 22  356  0  11.25  Jan. 14  379  0  27.968 *  Mar.  2  426  4  28.238 *  Mar. 25  449  4  Apr. 21  476  12  12.778 *  May  25  510  8  40.435 *  Aug. 11  223  4  17.195 *  Sept. 25  268  8  4.765 *  Oct. 23  296  4  54.882 *  Nov. 24  328  8  36.181 *  Dec. 21  355  8  7.498 *  Jan. 20  385  4  8.604 *  Mar.  9  433  16  33.3  Mar. 29  453  16  32.973 *  Apr. 29  484  8  May  27  512  12  5.675 *  8  189  12  1.399 ns  Sept. 20  263  0  15.357 *  Dec.  9  343  4  40.977 *  Feb. 18  414  8  25.310 *  May  492  0  8.976 *  3  (ppt)  s Va1ue +  b b  *  Rosewal1 C r . , 2°C incubation, 0-20  ppt.  gradient, (continued).  Rosewal1 C r . , 2°C incubation, 4-24 ppt. gradient.  July Coldwater R., Wild coho, 0-20 ppt. gradient. Age 0+ Res Idents,  7  4.313  18.22  *  *  *  a - Time ranges from 1-730 days which are equivalent to the calender dates January 1, 1982 to December 31, 1983. b - * - p<0.05, ns - p>0.05.  146  APPENDIX 9 (CONTINUED) SALINITY PREFERENCE DISTRIBUTION MODES AND MANN-WHITNEY U TEST COMPARISONS BETWEEN TEST AND CONTROL DISTRIBUTIONS.  Population & Treatment  Date  (ppt)  s Va1ue +  b b  8  9.775 *  June 15  531  8  1.988 *  July  7  188  8  25.546 *  Sept. 2  245  0  6.706 *  Dec. 15  349  0  2.903 *  Feb. 18  414  0  103.02 *  May  7  492  4  24.123 *  May  22  505  8  5.670 *  June  9  160  0  24.131 *  Dec.  6  340  4  5.770 *  July 13  194  4  Sept. 29  272  8  Dec.  3  337  8  43.02  Feb. 25  421  4  10.137 *  Apr. 30  485  16  15.543 *  May  23  508  16  0.551 ns  June 21  537  12  1.502 ns  July  9  190  8  Sept. 8  251  8  0.221 ns  Dec. 20  354  8  12.059 * .  Coldwater R., Wild coho, 0-20 ppt. gradient, Age 1+ Residents,  Age 1+ Residents,  Mode 9  506  May  Coldwater R., Wild coho, 4-24 ppt. gradient. Age 0+ Residents,  (day)  21  Coldwater R., Age 0+ Residents, (continued),  Age 0+ Migrants.  Time  (1982-83)  C  -c5.413 *  C  *  -c-  a - Time ranges from 1-730 days which are equivalent to the calender dates January 1, 1982 to December 31, 1983. b - * - p<0.05, ns - p>0.05. c - No control distributions were c o l l e c t e d . The modes given are for the t e s t d i s t r i b u t i o n .  147  APPENDIX 9 (CONTINUED) SALINITY PREFERENCE DISTRIBUTION MODES AND MANN-WHITNEY U TEST COMPARISONS BETWEEN TEST AND CONTROL DISTRIBUTIONS.  Population & Treatment  Date  Time  (1982-83)  (day)  Mode a  (ppt)  Va1ue  b  Coldwater R., Wild coho, 4-24 ppt. gradient Age 1+ ResIdents, (contlnued),  Feb. 26  391  4  14.019 *  May  1  486  16  8.558 *  May  24  509  12  2.01  *  Age 0+ Migrants.  June  6  157  16  1.30  ns  Dec.  3  337  8  3.569 *  14  134  4  26.994 *  June 10  161  4  9.118 *  July 17  198  4  40.577 *  Aug. 20  232  4  10.914 *  Sept. 30  273  0  41.306 *  O c t . 31  304  8  30.473 *  Nov. 26  330  16  16.345 *  Dec. 25  359  12  11.028 *  Feb.  2  398  12  Mar.  4  428  8  20.824 *  Apr.  3  458  12  9.283 *  May  8  493  16  9.433 *  June  8  524  16  0.243 ns  15  135  4  c  -c-  June 14  165  4  -c-  May Coldwater R., 6°C Incubation, 0-20 ppt. gradient.  Coldwater R., 6°C incubation, 4-24 ppt. gradient  May  0.648 ns  C  a - Time ranges from 1-730 days which are equivalent to the calender dates January 1, 1982 to December 31, 1983. b - * - p<0.05, ns - p>0.05. c - No control distributions were c o l l e c t e d . The modes given are for the t e s t d i s t r i b u t i o n .  148  APPENDIX 9 (CONTINUED) SALINITY PREFERENCE DISTRIBUTION MODES AND MANN-WHITNEY U TEST COMPARISONS BETWEEN TEST AND CONTROL DISTRIBUTIONS.  Population & Treatment  Coldwater R., 6"C Incubation, 4-24 ppt. gradient, (contlnued).  Coldwater R., 2°C Incubation, 0-20 ppt. grad1ent.  Date (1982-83)  Time (day)  July 17  Mode (ppt)  Value  198  4  18.202 *  Aug. 25  237  8  19.298 *  Sept. 27  270  4  23.892 *  Nov.  5  309  8  27.974 *  Dec.  2  336  12  16.564 «  Jan.  3  368  16  21.463 *  Feb.  4  400  20  Mar.  1  424  16  23.689 *  Apr.  1  455  4  5.035 *  May  2  487  12  10.172 *  June 11  527  16  4.361 *  July 29  210  4  21.528 *  Sept. 13  256  4  30.289 *  Oct.  9  282  0  31.527 *  Nov. 10  314  4  49.808 *  Dec. 22  356  12  1.982 *  Jan. 13  378  4  10.516 *  Feb. 17  413  12  27.388 *  Mar. 16  440  4  5.284 *  Apr. 18  473  16  7.016 *  May  516  0  4.699 *  31  3  b  1.255 ns  a - Time ranges from 1-730 days which are equivalent to the calender dates January 1, 1982 to December 31, 1983. b - * - p<0.05, ns - p>0.05.  149  APPENDIX 9 (CONTINUED) SALINITY PREFERENCE DISTRIBUTION MODES AND MANN-WHITNEY U TEST COMPARISONS BETWEEN TEST AND CONTROL DISTRIBUTIONS.  Population & Treatment Coldwater R., 2°C Incubation, 4-24 ppt. gradient.  Date (1982-83) Aug.  5  Time (day)  Mode 9  (ppt)  Va1ue  b  217  16  Sept. 12  255  4  40.78  Oct. 13  286  8  23.177 *  Nov. 16  320  16  18.251 *  Dec. 20  354  12  13.785 *  Jan. 19  384  16  34.133 *  Feb. 24  420  16  Mar. 20  444  12  16.177 *  Apr. 28  483  8  16.265 *  May  515  20  31  0.344 ns  2.641  1.93  *  *  ns  a - Time ranges from 1-730 days which are equivalent to the calender dates January 1, 1982 to December 31, b - * - p<0.05, ns - p>0.05.  1983.  


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