﻿74 
  REPORT 
  OF 
  COMMISSIONER 
  O?^ 
  FISH 
  AND 
  FISHERIES. 
  

  

  A 
  guard-rack 
  made 
  of 
  thin, 
  narrow 
  slats 
  is 
  arranged 
  on 
  an 
  incline 
  of 
  

   about 
  45°, 
  as 
  shown 
  at 
  C. 
  If 
  the 
  water 
  is 
  to 
  be 
  used 
  again 
  in 
  ponds 
  

   below, 
  a 
  receiver 
  is 
  built 
  underneath 
  the 
  bottom 
  of 
  the 
  pond 
  at 
  the 
  

   lower 
  end, 
  between 
  the 
  foot 
  of 
  the 
  guard-rack 
  and 
  the 
  dam-boards, 
  

   and 
  the 
  floor 
  of 
  the 
  pond 
  immediately 
  over 
  the 
  receiver 
  is 
  cut 
  away 
  and 
  

   fitted 
  with 
  a 
  grating. 
  This 
  allows 
  matter 
  to 
  fall 
  through 
  the 
  receiver 
  

   and 
  from 
  there 
  it 
  is 
  washed 
  through 
  the 
  sluiceway, 
  which 
  taps 
  the 
  

   receiver 
  by 
  drawing 
  the 
  gate 
  shown 
  at 
  D. 
  The 
  sluiceway, 
  E, 
  is 
  

   covered 
  and 
  leads 
  off 
  to 
  a 
  general 
  waste-ditch. 
  

  

  The 
  pond 
  is 
  provided 
  with 
  a 
  spawning-race 
  about 
  a 
  foot 
  deep, 
  4 
  feet 
  

   wide, 
  and 
  25 
  feet 
  long, 
  placed 
  at 
  the 
  upper 
  end 
  of 
  the 
  pond, 
  as 
  shown 
  

   at 
  H. 
  Three 
  division 
  boards 
  (shown 
  at 
  F), 
  about 
  12 
  feet 
  long 
  and 
  of 
  

   suitable 
  width 
  to 
  come 
  within 
  1 
  or 
  2 
  iuches 
  of 
  the 
  surface 
  of 
  the 
  water 
  

   when 
  the 
  pond 
  is 
  filled, 
  are 
  firmly 
  fixed 
  at 
  the 
  bottom. 
  The 
  object 
  of 
  

   these 
  boards 
  is 
  to 
  form 
  four 
  avenues 
  leading 
  to 
  the 
  raceway, 
  so 
  that 
  

   one 
  or 
  two 
  pugnacious 
  fish 
  can 
  not 
  command 
  the 
  approach 
  and 
  keep 
  

   back 
  spawning 
  fish 
  inclined 
  to 
  enter. 
  There 
  is 
  a 
  dam 
  across 
  the 
  race- 
  

   way 
  about 
  4 
  inches 
  high 
  (shown 
  at 
  G) 
  for 
  the 
  purpose 
  of 
  bringing 
  the 
  

   water 
  to 
  that 
  depth 
  in 
  the 
  lower 
  end, 
  so 
  that 
  when 
  the 
  trout 
  enter 
  they 
  

   will 
  find 
  sufficient 
  water 
  in 
  which 
  to 
  swim 
  freely, 
  and 
  not 
  be 
  inclined 
  

   through 
  fear 
  to 
  return 
  to 
  the 
  pond. 
  

  

  The 
  water 
  in 
  the 
  pond 
  is 
  of 
  sufficient 
  depth 
  to 
  bring 
  its 
  surface 
  

   within 
  6 
  inches 
  of 
  the 
  top 
  of 
  the 
  dam 
  in 
  the 
  raceway, 
  which 
  will 
  give 
  

   the 
  fish, 
  in 
  entering 
  the 
  raceway, 
  a 
  jump 
  of 
  7 
  inches, 
  allowing 
  1 
  inch 
  

   for 
  the 
  depth 
  of 
  water 
  on 
  the 
  dam 
  in 
  the 
  raceway. 
  This 
  distance 
  has 
  

   been 
  found 
  more 
  satisfactory 
  than 
  any 
  other, 
  and 
  spawning 
  fish 
  alone 
  

   will 
  go 
  up. 
  If 
  a 
  jump 
  of 
  less 
  than 
  7 
  inches 
  is 
  given, 
  other 
  fish 
  can 
  

   enter 
  the 
  raceway 
  without 
  much 
  exertion, 
  and 
  will 
  ascend 
  and 
  disturb 
  

   the 
  breeding 
  fish, 
  which, 
  when 
  spawning, 
  should 
  be 
  kept 
  strictly 
  by 
  

   themselves. 
  

  

  There 
  is 
  no 
  rule 
  regarding 
  the 
  supply 
  of 
  water 
  that 
  applies 
  to 
  a 
  

   spawning-pond 
  at 
  all 
  times 
  and 
  in 
  all 
  places. 
  It 
  is 
  necessarily 
  gov- 
  

   erned 
  by 
  the 
  temperature 
  of 
  the 
  water, 
  size 
  and 
  shape 
  of 
  the 
  pond, 
  

   size 
  of 
  the 
  fish 
  to 
  be 
  supported, 
  the 
  amount 
  of 
  shade, 
  etc. 
  For 
  a 
  

   pond 
  such 
  as 
  has 
  been 
  described, 
  where 
  water 
  is 
  plentiful, 
  at 
  least 
  200 
  

   gallons 
  per 
  minute 
  should 
  be 
  provided, 
  with 
  not 
  less 
  than 
  75 
  gallons 
  

   per 
  minute 
  as 
  a 
  minimum, 
  even 
  where 
  the 
  temperature 
  is 
  from 
  50 
  to 
  

   55 
  degrees 
  and 
  all 
  other 
  conditions 
  are 
  favorable. 
  While 
  the 
  former 
  

   amount 
  is 
  not 
  absolutely 
  necessary 
  for 
  the 
  support 
  of 
  the 
  fish, 
  it 
  

   insures 
  the 
  pond 
  being 
  kept 
  clean 
  and 
  the 
  fish 
  are 
  more 
  inclined 
  to 
  

   enter 
  the 
  raceway 
  at 
  spawning 
  time. 
  In 
  order 
  to 
  maintain 
  an 
  even 
  

   temperature 
  in 
  the 
  pond 
  the 
  earth 
  is 
  banked 
  against 
  the 
  sides 
  and 
  

   ends, 
  covering 
  the 
  framework 
  shown 
  on 
  plate 
  25, 
  and 
  the 
  embankments 
  

   are 
  made 
  broad 
  enough 
  on 
  top 
  to 
  admit 
  of 
  a 
  good 
  footway 
  around 
  the 
  

   ponds. 
  

  

  Such 
  a 
  pond 
  as 
  this 
  can 
  accommodate 
  from 
  1,000 
  to 
  1,500 
  breeding 
  

   fish. 
  Fish 
  must 
  not 
  be 
  overcrowded, 
  and 
  in 
  estimating 
  the 
  capacity 
  of 
  

  

  