﻿80 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  These 
  amounts 
  are 
  ample, 
  and 
  probably 
  even 
  half 
  would 
  suffice 
  if 
  it 
  

   were 
  necessary 
  to 
  economize 
  in 
  the 
  use 
  of 
  water. 
  In 
  reariug-ponds 
  

   more 
  water 
  is 
  required, 
  as 
  the 
  circulation 
  is 
  not 
  so 
  good 
  and 
  the 
  out- 
  

   door 
  exposure 
  causes 
  the 
  temperature 
  to 
  rise. 
  If 
  water 
  is 
  plentiful, 
  

   double 
  the 
  amounts 
  stated 
  would 
  be 
  advisable 
  for 
  pond-culture. 
  

  

  During- 
  the 
  last 
  two 
  seasons 
  at 
  Wytheville 
  80 
  to 
  85 
  per 
  cent 
  of 
  the 
  

   eggs 
  taken 
  j)roduced 
  fish, 
  of 
  which 
  about 
  70 
  per 
  cent 
  were 
  raised 
  to 
  

   three 
  months 
  old 
  and 
  55 
  per 
  cent 
  to 
  yearling 
  fish. 
  The 
  loss 
  in 
  eggs 
  

   was 
  almost 
  entirely 
  due 
  to 
  failure 
  in 
  impregnation, 
  very 
  few 
  being 
  lost 
  

   from 
  other 
  causes. 
  

  

  CARE 
  OF 
  EGGS 
  AND 
  FRY. 
  

  

  After 
  the 
  eggs 
  are 
  placed 
  on 
  the 
  trays, 
  the 
  only 
  attention 
  necessary 
  

   until 
  the 
  hatching 
  begins 
  is 
  to 
  keep 
  them 
  clean; 
  the 
  dead 
  eggs, 
  which 
  

   may 
  be 
  known 
  by 
  their 
  turning 
  white, 
  must 
  be 
  picked 
  out 
  at 
  least 
  once 
  

   each 
  day. 
  After 
  the 
  eye-spot 
  can 
  be 
  plainly 
  seen 
  it 
  is 
  well 
  to 
  run 
  a 
  

   feather 
  through 
  the 
  eggs 
  for 
  the 
  purpose 
  of 
  changing 
  their 
  position 
  

   on 
  the 
  trays, 
  and 
  to 
  disclose 
  any 
  foreign 
  matter 
  or 
  dead 
  eggs 
  that 
  

   may 
  be 
  hidden 
  underneath. 
  The 
  greatest 
  care 
  should 
  be 
  exercised 
  in 
  

   handling 
  the 
  eggs 
  at 
  any 
  time, 
  particularly 
  from 
  the 
  first 
  or 
  second 
  day 
  

   after 
  collection 
  up 
  to 
  the 
  appearance 
  of 
  the 
  eye-spot, 
  and 
  then 
  only 
  when 
  

   absolutely 
  necessary. 
  During 
  this 
  period, 
  the 
  eggs 
  are 
  very 
  delicate, 
  

   and 
  even 
  passing 
  a 
  feather 
  through 
  them 
  may 
  cause 
  a 
  heavy 
  loss. 
  

  

  The 
  time 
  required 
  for 
  hatching 
  depends 
  mainly 
  upon 
  the 
  temperature 
  

   of 
  the 
  water. 
  Eainbow 
  trout 
  eggs 
  will 
  hatch 
  in 
  water 
  at 
  50° 
  in 
  from 
  42 
  

   to 
  45 
  days, 
  each 
  degree 
  colder 
  taking 
  5 
  days 
  longer, 
  and 
  each 
  degree 
  

   warmer 
  5 
  days 
  less 
  ; 
  the 
  difference 
  increases 
  as 
  the 
  temperature 
  falls 
  

   and 
  diminishes 
  as 
  it 
  rises. 
  

  

  After 
  the 
  fry 
  hatch 
  they 
  require 
  but 
  little 
  attention 
  until 
  the 
  umbil- 
  

   ical 
  sac 
  is 
  absorbed 
  and 
  the 
  time 
  for 
  feeding 
  arrives. 
  They 
  are 
  exam- 
  

   ined 
  each 
  day, 
  and 
  the 
  dead 
  fish 
  and 
  decayed 
  matter 
  removed 
  from 
  

   the 
  troughs, 
  which 
  are 
  kept 
  perfectly 
  clean, 
  and 
  if 
  possible 
  provided 
  

   with 
  a 
  thin 
  layer 
  of 
  coarse 
  white 
  sand 
  on 
  the 
  bottom, 
  to 
  keep 
  the 
  fish 
  

   in 
  healthy 
  condition. 
  As 
  the 
  fish 
  grow 
  they 
  should 
  be 
  thinned 
  out 
  in 
  

   the 
  troughs, 
  from 
  time 
  to 
  time, 
  as 
  their 
  size 
  may 
  require. 
  When 
  they 
  

   first 
  begin 
  to 
  feed, 
  12,000 
  to 
  15,000 
  fish 
  to 
  the 
  trough 
  are 
  not 
  too 
  many; 
  

   but 
  by 
  the 
  time 
  they 
  get 
  to 
  be 
  1^ 
  to 
  li 
  inches 
  long 
  they 
  must 
  be 
  divided 
  

   into 
  lots 
  of 
  8,000 
  to 
  10,000 
  to 
  each 
  trough 
  ; 
  while 
  with 
  fish 
  averaging 
  3 
  

   inches 
  in 
  length, 
  3,000 
  to 
  4,000 
  are 
  as 
  many 
  as 
  one 
  trough 
  will 
  accom- 
  

   modate. 
  It 
  is 
  advisable 
  to 
  give 
  as 
  much 
  room 
  as 
  is 
  ]3racticable. 
  

  

  REARING-PONDS. 
  

  

  Ponds 
  for 
  rearing 
  trout 
  are 
  from 
  8 
  to 
  12 
  feet 
  wide, 
  and 
  of 
  any 
  desired 
  

   lengtb 
  up 
  to 
  60 
  feet, 
  which, 
  for 
  convenience 
  in 
  drawing 
  them 
  off 
  and 
  

   in 
  feeding 
  the 
  fish, 
  is 
  about 
  the 
  extreme 
  limit. 
  The 
  size, 
  shape, 
  and 
  

   arrangement 
  of 
  the 
  ponds 
  must 
  depend 
  upon 
  the 
  ground 
  on 
  which 
  

   they 
  are 
  to 
  be 
  constructed. 
  If 
  practicable, 
  it 
  is 
  best 
  to 
  build 
  tbem 
  on 
  a 
  

  

  