﻿280 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  PHYSICAL 
  AND 
  BIOLOGICAL 
  CONDITIONS 
  ON 
  OYSTER-BEDS. 
  

   TEMPERATURE 
  OF 
  WATER. 
  

  

  The 
  oyster 
  lives 
  in 
  waters 
  of 
  widely 
  varying 
  temperature, 
  both 
  as 
  to 
  

   the 
  average 
  for 
  the 
  year 
  and 
  the 
  extremes 
  met 
  with 
  at 
  different 
  

   seasons. 
  Perhaps 
  the 
  greatest 
  divergence 
  between 
  the 
  extremes 
  is 
  

   in 
  Chesapeake 
  Bay, 
  where 
  the 
  range 
  is 
  from 
  the 
  freezing-point 
  of 
  

   brackish 
  water, 
  something 
  below 
  32°, 
  to 
  90° 
  F. 
  In 
  New 
  Jersey 
  and 
  in 
  

   Chesapeake 
  Bay 
  the 
  shallow-water 
  oysters, 
  which 
  are 
  exposed 
  or 
  

   nearly 
  exposed 
  at 
  low 
  water, 
  are 
  frequently 
  frozen, 
  an 
  event 
  which 
  is 
  

   not 
  necessarily 
  fatal 
  if 
  they 
  are 
  gradually 
  thawed. 
  Young 
  oysters 
  

   in 
  shallow 
  water 
  are 
  sometimes 
  "winter-killed," 
  or 
  their 
  vitality 
  is 
  

   seriously 
  reduced, 
  by 
  exposure 
  to 
  exceptionally 
  low 
  temperatures. 
  The 
  

   remedy, 
  or 
  rather 
  preventive, 
  is 
  to 
  remove 
  to 
  deeper 
  water 
  in 
  the 
  fall, 
  

   and 
  seed 
  oysters 
  on 
  natural 
  spatting- 
  grounds 
  may 
  often 
  be 
  saved 
  by 
  

   this 
  means. 
  

  

  In 
  deeper 
  water, 
  such 
  as 
  is 
  found 
  on 
  the 
  offshore 
  beds 
  of 
  Long 
  Island 
  

   Sound, 
  they 
  are 
  not 
  subject 
  to 
  such 
  severe 
  trials, 
  but 
  are 
  nevertheless 
  

   called 
  upon 
  to 
  withstand, 
  during 
  several 
  months, 
  a 
  temperature 
  not 
  far 
  

   from 
  32° 
  F. 
  In 
  the 
  Long 
  Island 
  oyster 
  region 
  the 
  summer 
  temperature 
  

   of 
  the 
  water 
  reaches 
  75° 
  F,, 
  and 
  from 
  May 
  1 
  to 
  November 
  1 
  probably 
  

   never 
  falls 
  below 
  G0° 
  F. 
  On 
  the 
  South 
  Carolina 
  oyster-beds 
  the 
  tem- 
  

   perature 
  appears 
  to 
  rarely 
  fall 
  below 
  55° 
  F., 
  but, 
  on 
  the 
  other 
  hand, 
  

   the 
  exposed 
  banks 
  of 
  that 
  region 
  are 
  subjected 
  to 
  the 
  direct 
  rays 
  of 
  the 
  

   sun 
  and 
  therefore 
  withstand 
  a 
  temperature 
  considerably 
  Liigher 
  than 
  

   that 
  to 
  which 
  submerged 
  oysters 
  are 
  liable. 
  

  

  The 
  temperature 
  has 
  an 
  important 
  bearing 
  upon 
  the 
  food 
  supply. 
  

   When 
  the 
  water 
  is 
  warm 
  there 
  is 
  a 
  rapid 
  multiplication 
  of 
  the 
  small 
  

   forms 
  upon 
  which 
  the 
  oyster 
  feeds, 
  and 
  at 
  the 
  same 
  time 
  the 
  activities 
  

   of 
  the 
  oyster 
  itself 
  are 
  quickened. 
  The 
  two 
  facts 
  taken 
  together 
  result 
  

   in 
  a 
  more 
  rapid 
  growth 
  of 
  the 
  oyster 
  than 
  is 
  likely 
  to 
  take 
  place 
  in 
  

   colder 
  waters. 
  

  

  It 
  is 
  often 
  said 
  that 
  "plants 
  do 
  not 
  spawn," 
  and 
  there 
  appears 
  to 
  be 
  

   some 
  truth 
  in 
  the 
  statement 
  if 
  we 
  apply 
  it 
  to 
  a' 
  period 
  of 
  a 
  year 
  or 
  so 
  

   after 
  planting, 
  and 
  refer 
  to 
  cases 
  in 
  which 
  the 
  transplanting 
  has 
  iiuluced 
  

   considerable 
  modification 
  in 
  the 
  conditions 
  under 
  which 
  the 
  oyster 
  is 
  

   placed. 
  This 
  fact 
  is 
  no 
  doubt 
  largely 
  due 
  to 
  the 
  changes 
  in 
  temperature 
  

   to 
  which 
  the 
  oyster 
  is 
  subjected 
  when 
  transplanted. 
  Dr. 
  Ryder 
  says: 
  

  

  A 
  very 
  short 
  exposure 
  of 
  the 
  auimal 
  to 
  water 
  of 
  an 
  increased 
  temperature 
  caused 
  

   a 
  deterioration 
  of 
  the 
  generative 
  matter. 
  I 
  have 
  tried 
  to 
  fertilize 
  the 
  eggs 
  of 
  num- 
  

   bers 
  of 
  oysters 
  that 
  had 
  lain 
  over 
  night 
  m 
  the 
  Quinnipiak 
  River 
  and 
  invariably 
  

   failed; 
  the 
  eggs 
  in 
  every 
  case 
  appeared 
  to 
  be 
  overripe. 
  Oysters 
  taken 
  from 
  the 
  bed 
  

   at 
  the 
  same 
  time 
  and 
  from 
  the 
  same 
  locality, 
  but 
  kept 
  in 
  a 
  basket 
  over 
  night, 
  gave 
  

   good 
  results. 
  

  

  The 
  same 
  investigator 
  found 
  that 
  at 
  Beaufort, 
  N". 
  C, 
  the 
  best 
  results 
  

   m 
  fertilization 
  were 
  obtained 
  the 
  nearer 
  the 
  temperature 
  was 
  to 
  70° 
  F. 
  

   Both 
  at 
  Beaufort 
  and 
  in 
  Chesapeake 
  Bay 
  the 
  embryos 
  develop 
  most 
  

  

  