220 SPOLTA ZEYLANICA. 



the Persian Gulf, and the large mortality which would be inevitable, 

 probably renders such a scheme impracticable. 



Even after the spatfall has taken place, the young oysters are to a 

 great extent at the mercy of the elements and predatory fish. All 

 that the Marine Biologist can do is to *' thin out " the beds which 

 are overcrowded, and to transplant the spat from unfavourable 

 ground to the paars where good attachment is assured and where the 

 probable dangers of silting may be minimised. 



Admitting that predatory fish are one of the chief sources of 

 danger to the beds, it is difficult to know how their depredations 

 may be best arrested. Either vigorous and continued warfare must 

 be waged against these enemies of the pearl oyster, or the pearl oyster 

 itself must be protected. The difficulties in the way of the first of 

 these propositions have already been dealt with. To prosecute a 

 sufficient vigorous and effective campaign against these predaceous 

 fish over an area of many hundreds of square miles does not appear 

 to be practicable in the special circumstances of the case. 



The other alternative presents even greater difficulties than the 

 first. Nevertheless Mr. Southwell made provision for an experiment 

 of this nature , and following his suggestion the Company pvirchased 

 at a cost of £3,500 sufficient wire netting to cover one-sixth of a 

 square mile. It was proposed to laj^ this wire netting over a bed 

 of spat, and thus protect the oysters at the most critical period of 

 their life from the ravages of the natural enemies. Unfortunately 

 Mr. Southwell was not able to test the value of this experiment as 

 no spatfall occurred. The wu-e netting is now the property of 

 Government, and the experiment devised by Mr. Southwell will be 

 carried out when the first spatfall occurs. But it is quite obvious, 

 as Ml'. Southwell himself pointed out, that the cost of such a means 

 of protection is prohibitive, and the objection which Mr. Southwell 

 himself made in regard to Herdman's cultching proposals may be 

 made with equal force to the wire-netting experiment. 



In view of these difficulties, it is fortunate that when a spatfall 

 does take place it is usually so abundant that, on suitable ground, 

 a sufficient number of oysters survive for the requirements of a 

 fishery. On Periya Paar it is true that an excessive mortality of the 

 spat occurs, but this is probably not due so much to the attacks of 

 fishes as to other obscure causes. Since Periya Paar is so unsuitable , 

 the difficulties may be partly averted by extensive transplantation 

 as soon as a spatfall on this paar is discovered. For the reasons 

 which have already been stated, it is difficult to say whether the 

 establishment of breeding reserves is necessary, but as the question 

 involved is of too vital an importance to be dismissed by a mere 

 expression of personal opinion, the value of such reserves will be 

 tested when next the opportunity presents itself. 



For obvious reasons the question of artificial hatching of the 

 Ceylon pearl oyster has not yet been seriously considered. Artificial 



