﻿MANUAL 
  OF 
  FISH-CULTURE. 
  125 
  

  

  4 
  feet 
  wide, 
  and 
  4 
  to 
  8 
  or 
  more 
  feet 
  deep. 
  They 
  should 
  be 
  placed 
  end 
  

   to 
  end 
  in 
  two 
  rows, 
  some 
  3 
  or 
  4 
  feet 
  apart 
  with 
  a 
  plank 
  walk 
  between, 
  

   for 
  convenience 
  in 
  caring 
  for 
  them. 
  The 
  tish 
  must 
  be 
  handled 
  as 
  little 
  

   and 
  as 
  gently 
  as 
  possible, 
  otherwise 
  the 
  eggs 
  will 
  form 
  into 
  a 
  hard 
  mass 
  

   and 
  never 
  ripen. 
  One 
  cause 
  of 
  injury 
  is 
  the 
  scoop 
  net 
  with 
  which 
  they 
  

   must 
  be 
  handled; 
  the 
  knots 
  and 
  the 
  twine 
  are 
  so 
  hard 
  that 
  they 
  injure 
  

   the 
  delicate 
  scales 
  of 
  the 
  whitefish, 
  which 
  struggles 
  violently 
  when 
  

   taken 
  from 
  the 
  water. 
  A 
  net 
  made 
  by 
  punching 
  suitable 
  sized 
  holes 
  

   in 
  a 
  sheet 
  of 
  thin, 
  soft, 
  tlexible 
  rubber 
  would 
  be 
  yielding 
  and 
  perhaps 
  

   cause 
  the 
  least 
  injury. 
  

  

  HATCHING 
  METHODS 
  AND 
  EQUIPMENT. 
  

  

  At 
  Put-in 
  Bay 
  the 
  water 
  for 
  hatching 
  is 
  obtained 
  from 
  Lake 
  Erie 
  

   through 
  a 
  pipe 
  that 
  extends 
  75 
  to 
  100 
  feet 
  into 
  the 
  lake. 
  Pumps 
  

   elevate 
  the 
  water 
  to 
  the 
  loft 
  of 
  the 
  hatchery, 
  where 
  it 
  is 
  received 
  into 
  

   supply-tanks, 
  whence 
  it 
  is 
  distributed 
  by 
  the 
  usual 
  methods 
  of 
  piping. 
  

   The 
  circular 
  supply-tanks, 
  two 
  in 
  number, 
  are 
  about 
  11 
  feet 
  in 
  mean 
  

   diameter, 
  8 
  feet 
  high, 
  and 
  have 
  a 
  capacity«of 
  5,000 
  gallons 
  each. 
  These 
  

   tanks 
  are 
  necessary 
  to 
  give 
  an 
  equal 
  pressure 
  in 
  tlie 
  pipes 
  and 
  to 
  

   provide 
  a 
  supi^ly 
  of 
  water 
  in 
  the 
  event 
  of 
  cessation 
  of 
  i)umiiing. 
  A 
  

   gauge 
  in 
  the 
  boiler 
  room 
  shows 
  the 
  height 
  of 
  water 
  in 
  the 
  tanks. 
  

  

  Whitefish 
  eggs 
  are 
  hatched 
  in 
  the 
  McDonald 
  jar 
  and 
  the 
  Chase 
  jar; 
  

   the 
  former 
  is 
  in 
  more 
  general 
  use 
  in 
  the 
  United 
  States 
  Fish 
  Commission, 
  

   although 
  both 
  give 
  satisfactory 
  results. 
  The 
  eggs 
  are 
  put 
  into 
  the 
  

   hatching-jars 
  by 
  means 
  of 
  a 
  dipper 
  having 
  a 
  perforated 
  bottom. 
  The 
  

   proper 
  number 
  to 
  a 
  jar 
  is 
  3^ 
  quarts, 
  as 
  determined 
  by 
  a 
  gauge; 
  these 
  will 
  

   swell 
  to 
  4:1 
  quarts, 
  which 
  is 
  about 
  the 
  proper 
  quantity 
  for 
  the 
  jars 
  used. 
  

  

  The 
  form 
  of 
  the 
  embryo 
  Avhitefish 
  can 
  be 
  seen 
  in 
  the 
  egg 
  by 
  the 
  use 
  

   of 
  a 
  magnifying 
  glass 
  in 
  from 
  10 
  to 
  15 
  days 
  and 
  the 
  eye-specks 
  and 
  

   color 
  stars 
  in 
  from 
  15 
  to 
  20 
  days, 
  the 
  time 
  depending 
  much 
  on 
  the 
  tem- 
  

   perature 
  of 
  the 
  water. 
  The 
  fry 
  being 
  hatched, 
  the 
  food-sac 
  is 
  absorbed 
  

   in 
  from 
  5 
  to 
  15 
  days, 
  varying 
  somewhat 
  with 
  the 
  period 
  of 
  incubation. 
  

   If 
  hatching 
  is 
  long 
  retarded 
  by 
  low 
  temperatures, 
  the 
  sac 
  will 
  be 
  nearly 
  

   all 
  absorbed 
  when 
  the 
  fry 
  hatches. 
  

  

  The 
  microscope 
  is 
  a 
  great 
  aid 
  in 
  whitefish 
  culture, 
  enabling 
  the 
  

   operator 
  to 
  determine 
  the 
  exact 
  percentage 
  of 
  dead 
  eggs 
  and 
  to 
  a 
  great 
  

   extent 
  the 
  cause 
  of 
  their 
  loss, 
  thus 
  allowing 
  him 
  to 
  remedy 
  some 
  if 
  not 
  

   all 
  the 
  evils. 
  For 
  examining 
  eggs 
  in 
  their 
  early 
  stages 
  the 
  microscope 
  

   is 
  placed 
  horizontally, 
  the 
  eggs 
  being 
  held 
  in 
  a 
  cell 
  filled 
  with 
  water. 
  

   This 
  may 
  be 
  easily 
  made 
  by 
  fastening 
  two 
  ordinary 
  glass 
  slides 
  to 
  a 
  

   strip 
  of 
  wood 
  an 
  eighth 
  of 
  an 
  inch 
  thick, 
  with 
  a 
  portion 
  cut 
  away 
  to 
  

   form 
  a 
  receptacle 
  for 
  the 
  eggs. 
  The 
  wood 
  is 
  thoroughly 
  saturated 
  with 
  

   asphaltum 
  varnish, 
  and 
  after 
  drying 
  the 
  sides 
  should 
  receive 
  a 
  thin 
  

   coat, 
  the 
  slides 
  being 
  laid 
  on 
  and 
  placed 
  under 
  pressure 
  to 
  dry. 
  When 
  

   dry 
  an 
  additional 
  coat 
  to 
  the 
  outer 
  joints 
  of 
  contact 
  will 
  guard 
  against 
  

   possible 
  leaks. 
  

  

  