THE WIND OW- PANE OYSTERS. 



5^ 



The above figures show clearly enough a disturbance of meteoro- 

 logical conditions in the rainy season immediately preceding the 

 placuna fishery of 1907, and the same indications are continued 

 during February and March : — 



Inches. 



2-16 



0'93 



0*00 



February average 



1905 



1906 



1907 



March average 



1905 



1906 



1907 



1*48 

 1*48 

 0*03 

 0*22 

 1'94. 



REGBNERATIOISr OF THE TaMBLEGAM BeDS. 



The main object of placuna fishery investigations in Ceylon must 

 be to foster the Tamblegam fishery in particular. I have already 

 pointed out that it is not enough to limit the season and the size. 



In order to replenish the partially exhausted beds, some control 

 should be exercised over the breeding facilities so as to ensure 

 an adequate reserve of spawning oysters. It is an axiom among 

 European and American ostreiculturists " that the amount of spat 

 annually occurring in a region appears to be directly in proportion to 

 the number of spawning oysters in that region,"* This is evidently 

 a safe principle. 



The Nachchikkuda, being devoid of rivers opening into it, andbeing 

 by its position secluded to a great extent from other outside 

 influences, is peculiarly suitable for the introduction of simple and 

 inexpensive cultural operations. I would recommend the immediate 

 laying down of an enclosure about 30 feet square and thickly 

 planting the bottom with placunse, of which the average size has 

 been ascertained by previous measurement. By such means inform- 

 ation could in course of time be expected concerning actual rate of 

 growth, natural longevity, maturation, spawning, and distribution 

 of the fry. 



It is important to note that in spite of the mortality recorded in 

 this report, placuna is none the less a hardy mollusc, and can be 



* Bashford Dean. Report on the Em-opean Methods of Oyster-culture 

 Bull. U. S. Fish Commission for 1891 , pp. 357-406. Wasliington, 1 893- 



