﻿SPAWNING 
  SEASONS 
  OF 
  FISHES 
  PROPAGATED, 
  CHARACTER 
  

   OF 
  FISH 
  EGGS, 
  PERIOD 
  OF 
  INCUBATION, 
  ETC. 
  

  

  lu 
  tlie 
  following 
  table 
  there 
  are 
  x)resented, 
  in 
  a 
  form 
  convenient 
  for 
  

   reference, 
  some 
  of 
  the 
  more 
  important 
  facts 
  connected 
  with 
  eggs 
  of 
  the 
  

   fishes 
  artificially 
  cultivated 
  in 
  the 
  United 
  States. 
  It 
  should 
  be 
  under- 
  

   stood 
  that 
  there 
  is 
  considerable 
  variation 
  in 
  many 
  of 
  the 
  items, 
  depend- 
  

   ing 
  on 
  climatic 
  conditions, 
  size 
  and 
  age 
  of 
  fish, 
  etc. 
  ; 
  the 
  information 
  for 
  

   such 
  can 
  therefore 
  be 
  only 
  approximately 
  correct. 
  For 
  certain 
  of 
  the 
  

   less 
  important 
  fishes, 
  it 
  is 
  possible, 
  from 
  the 
  data 
  available, 
  to 
  supply 
  

   only 
  a 
  part 
  of 
  the 
  information 
  indicated 
  by 
  the 
  column 
  headings. 
  The 
  

   spawning 
  season 
  given 
  is 
  generally 
  that 
  of 
  wild 
  fish 
  in 
  the 
  regions 
  where 
  

   fish-cultural 
  work 
  is 
  i)rosecuted; 
  this 
  varies 
  much 
  with 
  latitude 
  and 
  

   local 
  conditions. 
  

  

  Fish 
  eggs, 
  as 
  regards 
  their 
  physical 
  characters, 
  naturally 
  fall 
  into 
  

   four 
  classes, 
  as 
  follows 
  : 
  

  

  (1) 
  Buoyant 
  or 
  floating, 
  as 
  the 
  eggs 
  of 
  the 
  cod, 
  mackerel, 
  and 
  most 
  

   pelagic 
  fishes, 
  which 
  come 
  to 
  the 
  surface 
  when 
  first 
  deposited 
  and 
  

   remain 
  there 
  during 
  at 
  least 
  the 
  early 
  stages 
  of 
  incubation. 
  

  

  (2) 
  Semi-buoyant, 
  as 
  the 
  eggs 
  of 
  the 
  shad 
  and 
  whitefish, 
  whose 
  spe- 
  

   cific 
  gravity 
  is 
  but 
  slightly 
  greater 
  than 
  that 
  of 
  water. 
  

  

  (3) 
  Heavy, 
  non-adhesive, 
  as 
  fha 
  eggs 
  of 
  salmon 
  and 
  trout. 
  

  

  (4) 
  Heavy, 
  adhesive 
  or 
  glutinous, 
  as 
  the 
  eggs 
  of 
  the 
  flatfish, 
  sea 
  her- 
  

   ring, 
  yellow 
  perch, 
  and 
  most 
  pond 
  fishes. 
  

  

  The 
  differences 
  in 
  the 
  types 
  of 
  hatching 
  apparatus 
  depend 
  primarily 
  

   on 
  the 
  foregoing 
  characters 
  of 
  the 
  eggs. 
  

  

  At 
  the 
  hatching 
  stations 
  the 
  size 
  of 
  eggs 
  is 
  determined 
  by 
  placing 
  a 
  

   number 
  of 
  moist 
  eggs, 
  shortly 
  after 
  taking, 
  on 
  a 
  flat 
  surface, 
  side 
  by 
  

   side, 
  and 
  noting 
  how 
  many 
  are 
  required 
  to 
  cover 
  a 
  linear 
  inch. 
  Owing 
  

   to 
  capillary 
  attraction 
  between 
  adjoining 
  eggs 
  leading 
  to 
  compression 
  

   or 
  flattening 
  of 
  the 
  contiguous 
  sides, 
  this 
  method 
  is 
  liable 
  to 
  slight 
  

   error, 
  the 
  extent 
  of 
  which 
  is 
  in 
  inverse 
  proportion 
  to 
  the 
  size 
  of 
  the 
  

   eggs. 
  

  

  By 
  means 
  of 
  the 
  microscope, 
  accurate 
  measurements 
  of 
  small 
  eggs 
  may 
  

   be 
  made. 
  The 
  size 
  of 
  eggs 
  of 
  a 
  given 
  species 
  often 
  varies 
  considerably, 
  

   sometimes 
  amounting 
  to 
  25 
  per 
  cent. 
  

  

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