﻿78 
  REPOET 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  fish 
  to 
  ascend 
  to 
  the 
  head 
  of 
  the 
  trough 
  and 
  receive 
  the 
  water 
  as 
  it 
  falls 
  

   from 
  the 
  screen, 
  which 
  is 
  very 
  beneficial. 
  Its 
  use 
  not 
  only 
  keeps 
  the 
  fry 
  

   clean 
  even 
  in 
  muddy 
  water, 
  but 
  also 
  reduces 
  the 
  loss 
  of 
  fry 
  from 
  suff'o- 
  

   cation 
  in 
  the 
  early 
  stages, 
  caused 
  by 
  their 
  banking 
  around 
  the 
  vertical 
  

   screens, 
  and 
  obviates 
  the 
  necessity 
  for 
  trough 
  covers 
  to 
  prevent 
  jumping, 
  

   as 
  trout 
  rarely 
  jump 
  where 
  the 
  horizontal 
  screen 
  has 
  been 
  adopted. 
  

  

  _o__ 
  ^ 
  ■> 
  ,-^.... 
  „ 
  ■> 
  fL 
  _ 
  

  

  LONGITUDINAL 
  SECTION 
  OF 
  HATCfUNQ 
  TROUGH.SHOWNG 
  POSITION 
  OF 
  HATCHING 
  TffAYS, 
  DAM, 
  £TC. 
  

  

  Hatching-troughs, 
  Guard-screen, 
  etc. 
  

   Hatching 
  trays 
  (C), 
  made 
  about 
  twice 
  as 
  long 
  ^s 
  wide, 
  i. 
  e., 
  28 
  by 
  

   13^, 
  are 
  convenient 
  to 
  handle 
  and 
  adjust 
  in 
  the 
  troughs. 
  The 
  sides 
  

   of 
  the 
  frame 
  are 
  made 
  of 
  good 
  pine 
  lumber, 
  dressed, 
  1 
  inch 
  square; 
  

   the 
  ends 
  are 
  dressed 
  J 
  by 
  1 
  inch, 
  and 
  are 
  cut 
  into 
  the 
  sides 
  to 
  form 
  a 
  

   smooth 
  surface 
  on 
  the 
  bottom 
  for 
  the 
  wire 
  filling. 
  The 
  wire 
  used 
  on 
  

   the 
  trays 
  is 
  woven 
  with 
  8 
  threads 
  to 
  the 
  inch, 
  with 
  a 
  mesh 
  f 
  inch 
  long, 
  

   and 
  should 
  be 
  well 
  galvanized 
  after 
  it 
  is 
  woven, 
  in 
  order 
  to 
  prevent 
  

   rusting 
  at 
  the 
  laps. 
  

  

  