﻿294 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  shells 
  are 
  gradually 
  dissolved 
  in 
  tlie 
  sea 
  water, 
  and 
  thus 
  furnish 
  the 
  lime 
  which 
  the 
  

   growing 
  oyster 
  needs 
  to 
  build 
  up 
  its 
  own 
  shell. 
  As 
  long 
  as 
  the 
  shell 
  is 
  soft 
  and 
  thin 
  

   the 
  danger 
  from 
  enemies 
  is 
  very 
  great, 
  and 
  this 
  danger 
  is 
  greatly 
  diminished 
  as 
  

   soon 
  as 
  the 
  shell 
  becomes 
  thick 
  enough 
  to 
  resist 
  attack. 
  It 
  is, 
  therefore, 
  very 
  neces- 
  

   sary 
  that 
  the 
  shell 
  should 
  bo 
  built 
  up 
  as 
  rapidly 
  as 
  possible, 
  and 
  an 
  abundant 
  supply 
  

   of 
  food 
  in 
  general 
  will 
  be 
  of 
  no 
  advantage 
  unless 
  the 
  supply 
  of 
  lime 
  is 
  great 
  enough 
  

   for 
  the 
  growth 
  of 
  the 
  shell 
  to 
  keep 
  pace 
  with 
  the 
  growth 
  of 
  the 
  body. 
  All 
  sea 
  

   water 
  contains 
  lime 
  in 
  solution, 
  but 
  the 
  percentage 
  is, 
  of 
  course, 
  greatest 
  near 
  the 
  

   sources 
  of 
  supply. 
  It 
  is 
  well 
  known 
  that 
  on 
  coral 
  reefs, 
  which 
  are 
  entirely 
  made 
  of 
  

   lime, 
  all 
  kinds 
  of 
  shelled 
  mollusks 
  liourish 
  in 
  unusual 
  abundance 
  and 
  have 
  very 
  

   strong 
  and 
  massive 
  shells, 
  and 
  our 
  common 
  laud 
  and 
  fresh- 
  water 
  snails 
  are 
  much 
  

   larger 
  and 
  more 
  abundant 
  in 
  a 
  limestone 
  region 
  than 
  in 
  one 
  where 
  the 
  supply 
  of 
  

   lime 
  is 
  scanty. 
  In 
  such 
  regions 
  it 
  is 
  not 
  unusual 
  to 
  hud 
  the 
  snails 
  gathered 
  around 
  

   old 
  decaying 
  bones, 
  to 
  which 
  they 
  have 
  been 
  drawn 
  in 
  order 
  to 
  obtain 
  a 
  supply 
  of 
  

   lime 
  for 
  their 
  shells. 
  

  

  From 
  all 
  these 
  causes 
  combined 
  it 
  results 
  that 
  a 
  young 
  oyster 
  which 
  settles 
  upon 
  a 
  

   natural 
  oyster-bed 
  has 
  a 
  much 
  better 
  chance 
  of 
  survival 
  than 
  one 
  which 
  settles 
  

   anywhere 
  else, 
  and 
  a 
  natural 
  bed 
  thus 
  tends 
  to 
  perpetuate 
  itself 
  and 
  to 
  persist 
  as 
  a 
  

   definite, 
  well-defined 
  area 
  ; 
  but 
  there 
  is 
  still 
  another 
  reason 
  . 
  As 
  the 
  flood 
  tide 
  rushes 
  

   up 
  the 
  channels 
  it 
  stirs 
  up 
  the 
  fine 
  mud 
  which 
  has 
  been 
  deposited 
  in 
  the 
  deep 
  water. 
  

   The 
  mud 
  is 
  swept 
  up 
  onto 
  the 
  shallows 
  along 
  the 
  shore, 
  and 
  if 
  these 
  are 
  level 
  much 
  of 
  

   the 
  sediment 
  settles 
  there. 
  If, 
  however, 
  the 
  flat 
  is 
  covered 
  by 
  groups 
  of 
  oysters, 
  the 
  

   ebl)iug 
  tide 
  does 
  not 
  flow 
  off 
  in 
  an 
  even 
  sheet, 
  but 
  is 
  broken 
  up 
  into 
  thousands 
  

   of 
  small 
  channels, 
  through 
  which 
  the 
  sediment 
  flows 
  down 
  to 
  be 
  swept 
  out 
  to 
  sea. 
  

  

  The 
  oyster-bed 
  thus 
  tends 
  to 
  keep 
  itself 
  clean, 
  and 
  for 
  these 
  various 
  reasons 
  it 
  

   follows 
  that 
  the 
  more 
  firmly 
  established 
  an 
  oyster 
  bed 
  is 
  the 
  better 
  is 
  its 
  chance 
  of 
  

   perpetuation, 
  since 
  the 
  young 
  spat 
  finds 
  more 
  favorable 
  conditions 
  where 
  there 
  are 
  

   oysters, 
  or 
  at 
  least 
  shells, 
  already 
  than 
  it 
  finds 
  anywhere 
  else. 
  

  

  Now, 
  what 
  is 
  the 
  practical 
  importance 
  of 
  this 
  description 
  of 
  a 
  natural 
  bed 
  ? 
  It 
  is 
  

   this: 
  Since 
  a 
  natnral 
  bed 
  tends 
  to 
  remain 
  permanent, 
  because 
  of 
  the 
  presence 
  of 
  

   oyster 
  shells, 
  the 
  shelling 
  of 
  bottoms 
  where 
  there 
  are 
  no 
  oysters 
  furnishes 
  us 
  with 
  a 
  

   means 
  of 
  establishing 
  new 
  beds 
  or 
  of 
  increasing 
  the 
  area 
  of 
  the 
  old 
  ones. 
  

  

  The 
  oyster-dredgers 
  state, 
  with 
  perfect 
  truth, 
  that 
  by 
  breaking 
  up 
  the 
  crowded 
  

   clusters 
  of 
  oysters 
  and 
  by 
  scattering 
  the 
  shells 
  the 
  use 
  of 
  the 
  dredge 
  tends 
  to 
  enlarge 
  

   the 
  oyster-beds. 
  The 
  sketch 
  which 
  we 
  have 
  just 
  given 
  shows 
  the 
  truth 
  of 
  this 
  claim, 
  

   but 
  this 
  is 
  a 
  very 
  rough 
  and 
  crude 
  way 
  of 
  accomplishing 
  this 
  end.* 
  

  

  This 
  desoription, 
  so 
  far 
  as 
  it 
  relates 
  to 
  tlie 
  oysters 
  tliemselves, 
  gives 
  

   a 
  good 
  idea 
  of 
  the 
  average 
  oyster-bed, 
  though 
  they 
  differ 
  somewhat 
  in 
  

   details 
  in 
  different 
  localities. 
  But, 
  as 
  shown 
  in 
  the 
  sections 
  which 
  treat 
  

   of 
  the 
  enemies 
  and 
  the 
  food 
  of 
  the 
  oyster, 
  the 
  latter 
  is 
  very 
  far 
  from 
  

   constituting 
  the 
  entire 
  population 
  of 
  the 
  beds. 
  The 
  same 
  causes 
  which 
  

   induce 
  the 
  growth 
  of 
  the 
  oyster, 
  the 
  firm 
  basis 
  of 
  attachment, 
  the 
  sur- 
  

   rounding 
  food-producing 
  mud, 
  the 
  favorable 
  deusity 
  and 
  temperature, 
  

   all 
  tend 
  to 
  make 
  the 
  oyster-bed 
  a 
  center 
  teeming 
  with 
  aquatic 
  life. 
  

   Thus 
  a 
  single 
  point 
  of 
  attachment, 
  a 
  firm 
  nucleus 
  projecting 
  naturally 
  

   above 
  the 
  surrounding 
  mud, 
  or 
  a 
  few 
  shells 
  thrown 
  upon 
  the 
  muddy 
  

   bottom 
  may 
  give 
  rise 
  to 
  a 
  community 
  where 
  life 
  is 
  as 
  abundant 
  and 
  the 
  

   struggle 
  for 
  existence 
  as 
  complex 
  and 
  strenuous 
  as 
  is 
  anywhere 
  found 
  

   in 
  nature. 
  

  

  * 
  Brooks, 
  W. 
  K., 
  Maryland 
  Oyster 
  Report, 
  1884, 
  pp. 
  86 
  to 
  88, 
  inclusive. 
  

  

  