﻿410 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  Reference 
  to 
  page 
  406 
  will 
  show 
  that 
  the 
  spring 
  spawning 
  occurs 
  in 
  

   Oak 
  Bay 
  during 
  a 
  period 
  when 
  the 
  surface 
  temperature 
  at 
  Eastport 
  

   ranges 
  between 
  36^° 
  F. 
  and 
  42° 
  F. 
  It 
  takes 
  place, 
  therefore, 
  on 
  a 
  

   rising 
  temperature. 
  The 
  surface 
  and 
  bottom 
  temperatures 
  keep 
  pace 
  

   with 
  one 
  another 
  during 
  their 
  rise 
  and 
  fall, 
  and 
  seldom 
  differ 
  by 
  more 
  

   than 
  1° 
  or 
  2° 
  in 
  the 
  depth 
  attainable 
  from 
  the 
  wharves 
  at 
  Eastport, 
  

   which 
  varied 
  from 
  2 
  to 
  30 
  feet. 
  

  

  An 
  examination 
  of 
  the 
  temperature 
  of 
  the 
  water 
  at 
  the 
  spawning 
  

   season 
  of 
  the 
  fall 
  herrings 
  at 
  various 
  places 
  on 
  the 
  coast 
  of 
  the 
  United 
  

   States 
  shows 
  some 
  interesting 
  facts. 
  Early 
  in 
  the 
  investigation 
  it 
  

   was 
  noticed 
  that 
  tlie 
  spawning 
  time 
  receded 
  in 
  date 
  westward 
  and 
  

   southward 
  along 
  the 
  coast, 
  and 
  that 
  the 
  temperature 
  of 
  the 
  water 
  at 
  

   any 
  given 
  time 
  became 
  progressively 
  higher 
  in 
  the 
  same 
  directions. 
  

   In 
  most 
  cases 
  the 
  temperature 
  observations 
  were 
  not 
  made 
  imme- 
  

   diately 
  upon 
  the 
  spawning-grounds, 
  but 
  many 
  of 
  the 
  stations 
  were 
  

   sufficiently 
  near 
  to 
  make 
  j)robable 
  but 
  a 
  very 
  slight 
  error 
  in 
  regarding 
  

   the 
  temperatures 
  as 
  identical. 
  

  

  In 
  order 
  to 
  examine 
  more 
  closely 
  into 
  the 
  relations 
  existing 
  between 
  

   the 
  temperature 
  of 
  the 
  water 
  and 
  the 
  spawning 
  time, 
  a 
  chart 
  was 
  

   prepared 
  showing 
  the 
  mean 
  temperature 
  of 
  five 
  years 
  at 
  a 
  number 
  of 
  

   stations 
  during 
  the 
  first 
  week 
  of 
  each 
  of 
  the 
  last 
  six 
  months 
  of 
  tiie 
  year, 
  

   the 
  temperatures 
  of 
  all 
  stations 
  at 
  each 
  period 
  being 
  connected 
  by 
  lines, 
  

   as 
  shown 
  in 
  plate 
  61. 
  From 
  the 
  data 
  before 
  given 
  the 
  spawning 
  season 
  

   at 
  each 
  j)lace 
  was 
  indicated 
  by 
  vertical 
  lines 
  connecting 
  its 
  approximate 
  

   or 
  average 
  date 
  of 
  beginning 
  and 
  ending 
  and 
  at 
  the 
  same 
  time 
  graphic- 
  

   ally 
  indicating 
  the 
  temperatures 
  prevailing 
  at 
  the 
  surface 
  of 
  the 
  water 
  

   during 
  the 
  herring's 
  term 
  of 
  reproductive 
  activity. 
  By 
  an 
  inspection 
  

   of 
  the 
  chart 
  it 
  will 
  be 
  seen 
  at 
  once 
  that 
  theie 
  is 
  an 
  apparently 
  close 
  

   relation 
  between 
  the 
  surface 
  temperature 
  and 
  the 
  time 
  of 
  sjiawning. 
  

   The 
  real 
  relationship 
  is, 
  of 
  course, 
  with 
  the 
  bottom 
  temperatures 
  in 
  

   which 
  the 
  actual 
  spawning 
  takes 
  place, 
  but 
  as 
  these 
  temperatures 
  were 
  

   available 
  in 
  but 
  one 
  or 
  two 
  places, 
  and 
  as 
  the 
  surface 
  and 
  bottom 
  read- 
  

   ings 
  rise 
  and 
  fall 
  j;«W 
  passu, 
  or 
  nearly 
  so, 
  it 
  was 
  considend 
  that 
  the 
  

   general 
  eftect 
  of 
  the 
  temperature 
  may 
  be 
  shown 
  as 
  well 
  by 
  the 
  one 
  

   series 
  as 
  by 
  the 
  other. 
  A 
  source 
  of 
  possible 
  error 
  arises 
  irom 
  the 
  fact 
  

   that 
  the 
  readings 
  were 
  not 
  made 
  actually 
  upon 
  the 
  spawning-grounds, 
  

   and 
  are 
  reported 
  from 
  independent 
  observations. 
  The 
  stations 
  at 
  which 
  

   the 
  meteorological 
  observations 
  were 
  made, 
  however, 
  are 
  so 
  close 
  to 
  the 
  

   observed 
  spawning-grounds 
  that 
  there 
  is 
  probably 
  but 
  a 
  small 
  ]iercent- 
  

   age 
  of 
  error 
  from 
  this 
  source, 
  and 
  the 
  bulk 
  of 
  the 
  spawning 
  at 
  the 
  place 
  

   named 
  may 
  safely 
  be 
  considered 
  as 
  accomplished 
  between 
  the 
  dates 
  and 
  

   temperatures 
  indicated. 
  

  

  As 
  shown 
  in 
  the 
  chart, 
  the 
  spawning 
  of 
  the 
  summer 
  and 
  fall 
  schools 
  

   of 
  herring 
  takes 
  place 
  at 
  a 
  temperature 
  between 
  47° 
  F. 
  and 
  57° 
  F., 
  

   independently 
  of 
  the 
  time 
  at 
  which 
  this 
  temperature 
  occurs 
  after 
  July 
  1. 
  

   West 
  of 
  Matinicus 
  Island 
  the 
  temiierature 
  is 
  within 
  this 
  range 
  In 
  

   spring 
  as 
  well 
  as 
  in 
  fall, 
  but 
  so 
  far 
  as 
  known 
  no 
  herring 
  spawn 
  in 
  that 
  

  

  