﻿MANUAL 
  OF 
  FISH-CULTURE. 
  113 
  

  

  pan 
  of 
  water. 
  Tliis 
  will 
  deaden 
  the 
  fall 
  of 
  the 
  eggs 
  from 
  oue 
  tray 
  to 
  

   the 
  other 
  aud 
  free 
  what 
  few 
  adhere 
  to 
  the 
  first 
  tray. 
  

  

  In 
  a 
  water 
  temperature 
  of 
  from 
  40° 
  to 
  45° 
  F., 
  hatching 
  will 
  begin 
  in 
  

   from 
  75 
  to 
  90 
  days. 
  The 
  dark 
  hue 
  of 
  the 
  egg 
  as 
  a 
  whole, 
  the 
  distinct 
  

   outliue 
  of 
  the 
  fish, 
  and 
  its 
  convulsive 
  movements 
  show 
  the 
  approach 
  

   of 
  the 
  hatching 
  period. 
  If 
  the 
  weather 
  is 
  clear 
  and 
  cold 
  these 
  indica- 
  

   tions 
  may 
  continue 
  for 
  some 
  time, 
  but 
  with 
  the 
  advent 
  of 
  a 
  single 
  warm 
  

   day 
  more 
  than 
  50 
  iter 
  cent 
  of 
  the 
  fry 
  are 
  apt 
  to 
  break 
  their 
  shells. 
  

  

  As 
  the 
  total 
  number 
  of 
  eggs 
  received 
  at 
  the 
  hatchery 
  lias 
  decreased, 
  

   in 
  order 
  to 
  determine 
  the 
  number 
  of 
  fry 
  that 
  will 
  be 
  hatched 
  they 
  are 
  

   now 
  measured 
  again 
  by 
  first 
  emptying 
  the 
  eggs 
  in 
  the 
  largo 
  pan 
  

   described 
  above, 
  aud 
  then 
  placing 
  4,000 
  each 
  upon 
  trays, 
  in 
  this 
  case 
  

   made 
  of 
  wire 
  cloth 
  with 
  a 
  -j^-inch 
  mesh. 
  Should 
  the 
  temperature 
  

   remain 
  uniform 
  the 
  hatching 
  will 
  cover 
  a 
  number 
  of 
  days, 
  but 
  a 
  sudden 
  

   rise 
  or 
  fall 
  in 
  the 
  tem'perature 
  will 
  have 
  a 
  marked 
  effect 
  in 
  either 
  

   advancing 
  or 
  retarding 
  the 
  further 
  develojimeut 
  of 
  the 
  eggs. 
  

  

  The 
  dead 
  shells 
  from 
  the 
  hatching 
  fish 
  must 
  be 
  removed 
  or 
  they 
  

   will 
  clog 
  the 
  trays 
  aud 
  stop 
  the 
  circulation 
  of 
  water. 
  To 
  provide 
  

   against 
  tliis, 
  one 
  box 
  of 
  trays 
  is 
  emptied 
  into 
  a 
  pan 
  of 
  water 
  and 
  the 
  

   eggs 
  stirred 
  with 
  a 
  feather; 
  the 
  shells 
  rise 
  to 
  the 
  to^) 
  and 
  can 
  be 
  easily 
  

   poured 
  off, 
  and 
  by 
  repeating 
  this 
  operation 
  several 
  times 
  the 
  hatching 
  

   fish 
  are 
  entirely 
  freed 
  from 
  this 
  refuse. 
  In 
  returning 
  the 
  fish 
  and 
  eggs 
  

   to 
  the 
  trays 
  they 
  should 
  be 
  divided 
  as 
  equally 
  as 
  possible 
  among 
  the 
  

   ten 
  trays. 
  The 
  necessity 
  for 
  this 
  depends 
  on 
  the 
  rapidity 
  of 
  hatching 
  

   and 
  perhaps 
  a 
  single 
  box 
  need 
  be 
  served 
  in 
  this 
  manner 
  only 
  three 
  

   or 
  four 
  times 
  during 
  the 
  hatching 
  period. 
  

  

  The 
  care 
  of 
  the 
  fry 
  from 
  this 
  time 
  to 
  their 
  distribution, 
  if 
  distributed 
  

   before 
  the 
  absorption 
  of 
  the 
  food-sac, 
  is 
  somewhat 
  similar 
  to 
  the 
  treat- 
  

   ment 
  described 
  for 
  eggs. 
  JMonstrosities, 
  " 
  blue-sacs," 
  and 
  dead 
  fry 
  are 
  

   picked 
  out 
  as 
  soon 
  as 
  they 
  are 
  discovered. 
  The 
  yolk-sac 
  attached 
  to 
  

   the 
  fry 
  will 
  be 
  gradually 
  absorbed 
  and 
  the 
  fry 
  so 
  increase 
  in 
  size 
  that 
  

   4,000 
  overcrowd 
  one 
  tray, 
  and 
  when 
  the 
  sac 
  is 
  about 
  half 
  gone, 
  which 
  

   is 
  in 
  about 
  three 
  or 
  four 
  weeks 
  after 
  the 
  fish 
  are 
  hatched, 
  it 
  is 
  necessary 
  

   to 
  reduce 
  the 
  number 
  upon 
  each 
  tray 
  to 
  2,000. 
  

  

  DISTRIBUTION 
  OF 
  THE 
  FRY. 
  

  

  Lake 
  trout 
  should 
  either 
  be 
  planted 
  while 
  the 
  food-sac 
  is 
  still 
  visible, 
  

   or 
  not 
  until 
  they 
  possess 
  the 
  vitality 
  of 
  the 
  yearling. 
  Trout 
  planted 
  

   when 
  the 
  food-sac 
  is 
  within 
  one 
  or 
  two 
  weeks 
  of 
  complete 
  absorption 
  

   have 
  sufficient 
  nourishment 
  to 
  sustain 
  life 
  until 
  they 
  are 
  acclimated 
  to 
  

   their 
  surroundings, 
  as 
  well 
  as 
  the 
  natural 
  impulse 
  from 
  the 
  beginning 
  to 
  

   take 
  the 
  minute 
  particles 
  of 
  food 
  which 
  they 
  find. 
  As 
  from 
  2,000,000 
  to 
  

   4,000,000 
  lake 
  trout 
  are 
  hatched 
  at 
  Northville 
  annually, 
  it 
  is 
  impossible, 
  

   with 
  the 
  present 
  facilities, 
  to 
  hold 
  them 
  all 
  in 
  rearing-troughs 
  and 
  ponds 
  

   until 
  they 
  become 
  yearlings, 
  and 
  the 
  fry 
  are 
  usually 
  distributed 
  direct 
  

   from 
  the 
  hatching-boxes. 
  

  

  r. 
  C. 
  R. 
  1897 
  8 
  

  

  