1922] MADRAS PEARL FISHERIES 163 



encouragement be given to fishermen to go there and fish for 

 Vellamin and Trigger-fish {Kilati) as these are the great enemies 

 of the pearl-oyster at this age. 



Stone anchors should, however, be interdicted, and the use of 

 grapnels or iron anchors insisted on. 



At other times, except when the pearl-oysters are in their 

 third year, I should recommend fishing to be permitted with the 

 one restriction regarding the non-employment of stone anchors. 



When oysters on a bank approach maturity probably it would 

 be advisable to prohibit fishing — this chiefly for two reasons, the 

 one being the danger of disturbance of the oysters, and the other 

 that at this time sponge-eating fish {Holacanthus spo.), Gymnodonts, 

 Vellamin (Lethrinus spp.), and Trigger-fish perform a useful func- 

 tion in devouring and helping to keep under various competing 

 organisms, sponges, small molluscs (suran and brood oysters), and 

 crusting growths that overload and overrun the valves of the older 

 oysters. 



(Ill) 



Determination of Surface-drift over the banks. 



An accurate knowledge of the movement of the surface-water 

 over the pearl banks is a matter of the utmost importance in their 

 management. Without this knowledge we cannot form even an 

 approximately accurate idea of the source whence comes the spat 

 that from time to time replenishes one or other of our banks. So 

 long as we are in the dark upon this subject, we cannot define in 

 what location a reserve of oysters should be to produce the most 

 useful results. There are banks so situated as to be normally of 

 no breeding value, of no importance in replenishing the banks 

 which are our reliance ; conversely certain banks must be of 

 supreme importance in the conservation of our beds, and it is 

 obvious that information on these points is of vital importance in 

 the farming of the banks. It should be ascertained whether any 

 proportion of the spat that settles, say on the Tolayiram Par, 

 originated from the oyster beds on the Ceylon side of the Gulf of 

 Mannar, whether the converse be the case, or again whether there 

 be mutual interchange of spat. 



The plan offering the greatest advantages is to obtain the co- 

 operation of the Ceylon Government in order to secure both uni- 

 formity of method and mutual assistance in carrying on this 



