﻿MANUAL 
  OF 
  FISH-CULTURE. 
  121 
  

  

  ary, 
  1897, 
  many 
  of 
  these 
  animals 
  were 
  pumped 
  up 
  with 
  the 
  water 
  

   supply 
  of 
  Put-in 
  Bay 
  station. 
  The 
  stomachs 
  of 
  a 
  considerable 
  number 
  

   of 
  them 
  ccmtained 
  whitefish 
  and 
  cisco 
  eggs, 
  the 
  contents 
  of 
  one 
  stomach 
  

   being 
  288 
  whitefish 
  and 
  4 
  cisco 
  eggs. 
  

  

  Another 
  voracious 
  destroyer 
  of 
  the 
  whitefish 
  is 
  the 
  common 
  yellow 
  

   perch 
  {Verca 
  Jiavescens). 
  The 
  deck 
  of 
  a 
  boat 
  has 
  been 
  seen 
  covered 
  

   with 
  the 
  eggs 
  of 
  the 
  whitefish 
  and 
  cisco 
  pressed 
  out 
  of 
  the 
  stomachs 
  of 
  

   perch 
  taken 
  from 
  gill 
  nets 
  the 
  last 
  of 
  November 
  on 
  the 
  reefs, 
  where 
  thej^ 
  

   had 
  gone 
  to 
  feed 
  on 
  the 
  eggs. 
  

  

  The 
  various 
  smaller 
  CyiyrlnUhv 
  and 
  some 
  other 
  fishes, 
  crawlish, 
  and 
  

   wild 
  fowl 
  make 
  the 
  eggs 
  of 
  fishes 
  a 
  considerable 
  portion 
  of 
  their 
  diet, 
  

   those 
  which 
  require 
  the 
  longest 
  period 
  in 
  hatching, 
  of 
  course, 
  suffering 
  

   most. 
  

  

  ARTIFICIAL 
  PROPAGATION. 
  

  

  The 
  artificial 
  propagation 
  of 
  whitefish 
  has 
  long 
  since 
  passed 
  the 
  

   exi)eriniental 
  stage 
  and 
  has 
  attained 
  a 
  high 
  degree 
  of 
  perfection. 
  The 
  

   work 
  can 
  be 
  carried 
  on 
  with 
  great 
  facility, 
  and 
  its 
  value 
  is 
  especially 
  

   apparent 
  when 
  it 
  is 
  considered 
  that 
  nnder 
  natural 
  conditions 
  only 
  

   a 
  very 
  small 
  percentage 
  of 
  the 
  eggs 
  hatch, 
  while 
  through 
  artificial 
  

   propagation 
  from 
  75 
  to 
  95 
  per 
  cent 
  are 
  productive. 
  J'ractically 
  all 
  the 
  

   eggs 
  taken 
  for 
  hatching 
  purposes 
  are 
  obtained 
  from 
  fish 
  caught 
  by 
  the 
  

   commercial 
  fishermen, 
  which 
  would 
  otherwise 
  be 
  lost. 
  

  

  The 
  methods 
  of 
  culture 
  hereafter 
  referred 
  to 
  are 
  those 
  adopted 
  at 
  

   the 
  Putin 
  Bay 
  (Ohio) 
  station, 
  but 
  these 
  do 
  not 
  differ 
  in 
  any 
  essential 
  

   particular 
  from 
  those 
  in 
  general 
  use. 
  

  

  In 
  the 
  fiscal 
  year 
  1895-1)G 
  the 
  United 
  States 
  Fish 
  Commission 
  hatched 
  

   and 
  planted 
  189,690,000 
  whitefish 
  fry, 
  and 
  in 
  the 
  subsequent 
  year 
  

   95,049,000 
  fry 
  were 
  hatched 
  and 
  liberated 
  in 
  suitable 
  waters. 
  

  

  HOW 
  THE 
  ECiG« 
  ARE 
  TAKEN 
  AND 
  TREATED. 
  

  

  The 
  taking, 
  impregnating, 
  and 
  handling 
  of 
  the 
  whitefish 
  eggs 
  are 
  

   simple 
  processes, 
  but 
  require 
  great 
  care 
  at 
  every 
  stage. 
  Eggs 
  are 
  

   often 
  injured 
  by 
  undue 
  haste 
  in 
  stripjung, 
  and 
  many 
  are 
  lost 
  by 
  allowing 
  

   them 
  to 
  fall 
  too 
  great 
  a 
  distance 
  into 
  tlie 
  spawning-pan. 
  Eggs 
  are 
  very 
  

   delicate 
  when 
  first 
  taken 
  and 
  before 
  the 
  absorption 
  of 
  water 
  has 
  made 
  

   the 
  investing 
  membrane 
  tense, 
  and 
  if 
  roughly 
  treated 
  will 
  be 
  seen 
  to 
  be 
  

   ruptured 
  as 
  viewed 
  under 
  the 
  microscope. 
  Witli 
  care 
  about 
  four 
  fifths 
  

   of 
  the 
  eggs 
  will 
  hatch. 
  Improper 
  attention 
  to 
  the 
  impregnating 
  process 
  

   may 
  also 
  result 
  in 
  serious 
  loss 
  of 
  eggs. 
  While 
  scarcity 
  of 
  milt 
  may 
  

   load 
  to 
  the 
  nonfertilization 
  of 
  the 
  eggs, 
  the 
  manner 
  in 
  which 
  the 
  milt 
  is 
  

   brought 
  in 
  contact 
  with 
  eggs 
  is 
  a 
  more 
  common 
  cause 
  of 
  failure. 
  

  

  The 
  eggs 
  supplied 
  by 
  each 
  spawn-taker 
  should 
  be 
  examined 
  daily, 
  

   and 
  if 
  it 
  is 
  found 
  that 
  a 
  considerable 
  number 
  have 
  ruptured 
  yolks 
  it 
  may 
  

   be 
  taken 
  for 
  granted 
  that 
  the 
  spawn-taker 
  has 
  handled 
  the 
  fish 
  and 
  eggs 
  

   roughly, 
  and 
  if 
  many 
  are 
  unimpregnated 
  it 
  is 
  evident 
  that 
  he 
  did 
  not 
  

   use 
  sufticient 
  milt 
  or 
  that 
  it 
  was 
  not 
  properly 
  applied 
  to 
  the 
  eggs. 
  

  

  