﻿203 
  

  

  ON 
  FISH 
  AND 
  MOSQUITOS 
  IN 
  PALESTINE. 
  

   By 
  P. 
  A. 
  Buxton, 
  M.R.C.S., 
  L.R.C.P., 
  D.T.M.&H., 
  

  

  Fellow 
  of 
  Trinity 
  College, 
  Cambridge 
  ; 
  Government 
  Laboratory, 
  Jerusalem, 
  Palestine. 
  

  

  One 
  of 
  the 
  greatest 
  difficulties 
  of 
  anti-mosquito 
  work 
  in 
  Palestine 
  is 
  that 
  there 
  

   are 
  a 
  series 
  of 
  swamps 
  in 
  the 
  littoral 
  plain, 
  lying 
  almost 
  at 
  sea 
  level 
  and 
  prevented 
  

   from 
  draining 
  into 
  the 
  Mediterranean 
  by 
  sand-dunes 
  and 
  sand-bars 
  which 
  block 
  

   their 
  outlet 
  channels. 
  It 
  appears 
  that 
  cutting 
  channels 
  through 
  the 
  coastal 
  dunes 
  

   is 
  a 
  task 
  which 
  would 
  have 
  to 
  be 
  repeated 
  at 
  very 
  frequent 
  intervals, 
  and 
  until 
  some- 
  

   what 
  large 
  sums 
  of 
  money 
  are 
  available 
  the 
  pumping 
  of 
  these 
  numerous 
  swamps 
  

   into 
  the 
  sea 
  cannot 
  be 
  undertaken. 
  There 
  are, 
  moreover, 
  other 
  rather 
  large 
  areas 
  

   of 
  marsh, 
  notably 
  Lake 
  Huleh, 
  Beisan 
  marsh 
  and 
  the 
  Marj 
  Sanour, 
  the 
  proper 
  drainage 
  

   of 
  which 
  is 
  at 
  the 
  moment 
  beyond 
  the 
  financial 
  resources 
  of 
  the 
  country. 
  We 
  have 
  

   therefore 
  to 
  rely 
  for 
  the 
  moment 
  on 
  ameliorative 
  measures 
  which 
  are 
  admittedly 
  

   not 
  sufficiently 
  radical. 
  Among 
  other 
  things, 
  I 
  have 
  begun 
  a 
  study 
  of 
  our 
  native 
  

   fish, 
  hoping 
  to 
  find 
  some 
  small 
  and 
  voracious 
  species 
  that 
  breeds 
  rapidly 
  and 
  is 
  able 
  

   to 
  live 
  in 
  waters 
  of 
  different 
  degrees 
  of 
  salinity. 
  The 
  results 
  which 
  I 
  have 
  obtained 
  

   are 
  perhaps 
  discouraging, 
  but 
  certainly 
  interesting. 
  

  

  The 
  problem 
  is 
  essentially 
  one 
  of 
  oecology 
  ; 
  we 
  must 
  study 
  the 
  mosquito 
  larvae 
  

   and 
  fish 
  in 
  their 
  natural 
  environment, 
  and 
  endeavour 
  to 
  find 
  out 
  whether 
  they 
  are 
  

   in 
  any 
  way 
  dependent 
  one 
  on 
  the 
  other. 
  If 
  we 
  have 
  reason 
  to 
  hope 
  that 
  a 
  particular 
  

   species 
  of 
  fish 
  occasionally 
  takes 
  mosquito 
  larvae, 
  then 
  any 
  information 
  about 
  its 
  

   food 
  in 
  a 
  state 
  of 
  nature 
  is 
  relevant. 
  It 
  appears 
  to 
  me 
  that 
  no 
  laboratory 
  experiment 
  

   is 
  valid 
  in 
  elucidating 
  a 
  problem 
  such 
  as 
  this 
  ; 
  the 
  conditions 
  of 
  experiment 
  can 
  never 
  

   adequately 
  reproduce 
  the 
  complex 
  conditions 
  which 
  prevail 
  in 
  the 
  marsh. 
  I 
  have 
  

   therefore 
  confined 
  myself 
  to 
  examining 
  the 
  guts 
  of 
  fish 
  caught 
  in 
  their 
  natural 
  home 
  

   and 
  preserved 
  by 
  being 
  put 
  instantly 
  into 
  70 
  per 
  cent, 
  alcohol, 
  or 
  4 
  per 
  cent, 
  formalde- 
  

   hyde 
  ; 
  and 
  I 
  may 
  remark 
  in 
  passing 
  that 
  this 
  method 
  of 
  preservation 
  is 
  adequate 
  

   for 
  fish 
  up 
  to 
  3-4 
  in. 
  long. 
  Penetration 
  of 
  the 
  formalin 
  or 
  alcohol 
  is 
  so 
  quick 
  and 
  

   good 
  that 
  I 
  have 
  been 
  able 
  to 
  observe 
  the 
  nuclear 
  characteristics 
  of 
  Vorticellids 
  in 
  a 
  

   Cyprinodon 
  which 
  has 
  been 
  preserved 
  for 
  several 
  months. 
  Specimens 
  of 
  all 
  species 
  

   of 
  fish 
  examined 
  have 
  been 
  determined 
  by 
  Mr. 
  C. 
  Tate 
  Regan, 
  F.R.S. 
  The 
  results 
  

   obtained 
  are 
  as 
  follows 
  : 
  — 
  

  

  1. 
  Young 
  Mugil 
  sp. 
  (family 
  Mugilidae), 
  2 
  in. 
  long, 
  from 
  the 
  Kishon 
  marshes, 
  

   July 
  ; 
  1 
  1 
  dissected. 
  None 
  contained 
  any 
  animal 
  matter 
  of 
  any 
  sort. 
  They 
  

   were 
  packed 
  with 
  diatoms, 
  and 
  had 
  also 
  taken 
  other 
  unicellular 
  algae, 
  Volvocales, 
  

   Dinoflagellates 
  and 
  grit. 
  

  

  2. 
  Tilapia 
  zillii 
  (family 
  Cichlidae), 
  specimens 
  from 
  1-4 
  in. 
  long, 
  from 
  the 
  Kishon 
  

   marshes, 
  July 
  ; 
  Nahr 
  Barideh, 
  Jaffa, 
  December 
  ; 
  and 
  Beisan, 
  June. 
  In 
  each 
  case 
  

   fish 
  came 
  from 
  water 
  in 
  which 
  mosquito 
  larvae 
  could 
  be 
  found, 
  though 
  generally 
  

   the 
  larvae 
  were 
  well 
  protected 
  in 
  shallow 
  bays 
  or 
  among 
  dense 
  weeds. 
  The 
  following 
  

   were 
  found 
  in 
  31 
  stomachs 
  and 
  intestines 
  examined 
  : 
  in 
  every 
  individual 
  diatoms 
  

   and 
  grit 
  and 
  Copepods 
  ; 
  in 
  21 
  individuals, 
  filamentous 
  algae 
  ; 
  in 
  10 
  individuals, 
  

   Volvocales 
  ; 
  in 
  2 
  or 
  3 
  individuals, 
  Ostracods, 
  Vorticellids, 
  jumping 
  Rotifers, 
  pieces 
  

   of 
  grass, 
  small 
  Nematocerous 
  larvae, 
  and 
  undetermined 
  insects 
  ; 
  in 
  single 
  individuals, 
  

   Cladocera, 
  adult 
  Leptoconops 
  (Chironomidae), 
  beetle 
  larvae, 
  and 
  Hydrachnids. 
  To 
  

   summarise 
  these 
  results 
  one 
  may 
  say 
  that 
  Tilapia 
  zillii 
  takes 
  a 
  wide 
  range 
  of 
  food, 
  

   animal 
  and 
  vegetable, 
  but 
  that 
  we 
  have 
  at 
  present 
  no 
  record 
  of 
  mosquito 
  larvae 
  

   being 
  found 
  in 
  its 
  alimentary 
  canal. 
  I 
  understand 
  from 
  Dr. 
  L. 
  H. 
  Gough 
  that 
  in 
  

   Egypt 
  a 
  species 
  of 
  Tilapia 
  locally 
  known 
  as 
  " 
  Bolte 
  " 
  has 
  been 
  distributed 
  as 
  a 
  

   mosquito 
  destroyer, 
  and 
  that 
  its 
  introduction 
  has 
  been 
  followed 
  by 
  a 
  reduction 
  in 
  the 
  

   number 
  of 
  mosquitos 
  and 
  of 
  cases 
  of 
  malaria 
  in 
  certain 
  areas. 
  

  

  