24 



99. Backwater beds form the third and most valuable class. On the Sind 

 coast they are restricted to the western section of the Karachi backwater ; they 

 comprise the well-known Nawa Nar or Mauripur beds. Reference to any plan 

 of the backwater (see Fig. 1) shows how excellent this location is for the 

 well-being of oysters. No large river is present at the western end ; whatever 

 fresh water enters during the rains is absorbed at once by the vast body of 

 tidal water that presses up the channels twice a day. Rocky ground forms the 

 northern boundary and outcrops here and there from the bottom ; these reefs 

 and submerged ridges and the gravels and boulders associated with them form 

 the best of natural cultch materials and provide them in considerable 

 abundance. The great areas of shallow water found at every state of the tide and 

 the high temperature of the water for the greater part of the year are condi- 

 tions highly favourable to the growth of the diatomaceous food-supply required 

 by oysters and as a consequence the growth and fattening of oysters, so far as 

 the observations made enable me to judge, appear to be unusually rapid. 



100. Ample direct confirmation was obtained during the enquiry of the 

 present complete exhaustion of all oyster beds on the Sind coast save in some 

 part, those of the Hab river. 



101. The Nawa Nar beds in actuality DO longer exist ; here and there a 

 few dozen oysters may be gathered but this is at the expense of much time and 

 trouble. No massing of oysters is to be seen anywhere, merely the occurrence 

 of single individuals scattered here and there at considerable intervals. The 

 beds in Kuranji and Kadero creeks have fared even worse, and nothing but 

 dead shells mark the place where very rich deposits existed till 1890. In the 

 creeks southward there is an appearance of rather better conditions ; a two- 

 years' closure of the beds had just terminated and some of the patches examined 

 had recovered to some degree. This improvement was a most valuable object 

 lesson as it enabled me to learn precisely the extent of nature's power in 

 restoring the prosperity of a bed when given the time aud opportunity to do so. 

 The operations of the oystermen whom I saw engaged in collecting oysters 

 afforded me the requisite information on the converse proposition of how 

 quickly unrestricted fishing may exhaust the improvement made during the 

 period of closure. 



102. The only beds which do not show evidence of complete depletion are 

 those of the Bab river. There every rock and every object fit to give footing to 

 oysters are covered with them in densely packed masses. The general size was 

 small and stunted due to mutual crowding, the consequence of insufficient 

 cultch surfaces for the multitudes of spat emitted by the adult oysters found 

 there. I was informed, however, that alterations in the course of the river have 

 involved the silting up of many good rocky patches and other cultch, so that the 

 oyster population at this place is Je.'S than it was pome years since. The size- 

 quality of the oysters is the fault here and not that of actual scarcity* of 

 individuals. On the other beds the fault is actual depletion of the oyster 

 population ; at the Hab, it is deterioration of quality that is the fault. 



fc 



103. Causes of depletion. My inspection of the beds confirmed fully the 

 views which attribute the present exhaustion of the beds to the evils of overfish- 

 ing. No other conclusion is possible. Overfishing is without doubt the main 

 and preponderating cause of this catastrophe, emphasized and hastened, however, 

 by the coincidence of several minor factors during the period when overfishing 

 was being most actively pursued. The historical evidence given on a fore- 

 going page and the pictures of the present-day condition drawn in the section 

 dealing with the record of my inspection of the beds furnish convincing testi- 

 mony and need be laboured no further. It is abundantly clear that in the 

 past treatment of these beds the first principle of oyster cult ure, namely that 

 the average number of oysters annually removed must not exceed the number 

 annually bred and reared to a marketable size, has been consistently violated. 



104. Of the minor contributory causes the most important have been, (a) 

 cyclones, (b) freshets of the Indus and the Hab, (<?) mara pani, poisonous and 

 sulphuretted water of obscure origin. All three have played their part, 

 aggravating locally the mischief being done generally by overfishing. It 



