CEYLON PEARL BANKS. 211 



manner. As Jameson has pointed out, Hornel] transplanted a, 

 batch of 10,000,000 oysters, but no subsequent report indicates 

 whether the experiment was a success or failure. Southwell also 

 transplanted 9,000,000 oysters, but they all died in the following year. 

 One has every reason to believe that transplantation operations, 

 if carried out on a sufficiently large scale, will prove an important 

 factor in the improvement of the banks, and in consequence it 

 will be of interest to follow the results of future transplantation 

 experiments. 



Transplanting is not only necessary to relieve overcrowding, but 

 also in cases where a spatfall takes place on unsuitable ground. 

 For example, Periya Paar frequently receives large deposits of spat 

 which rarely reach maturity. In such a case, whenever a spatfall 

 occurs, the young oysters should be dredged up and deposited on 

 more suitable ground. 



It is questionable whether the dangers of overfishing are so serious 

 as would appear at first sight. Professor Herdman strongly empha- 

 sized the evils of overfishing in his reports, but it is significant that 

 in his final recommendations no mention is made of any provision 

 against overfishing. It is probable that the pearl oyster matures 

 at least two years before it is " fishable," and so far as one can 

 determine it does not live long after the fishable age. It has been 

 suggested that overfishing may be prevented by marking off certain 

 " spawning reserves '" during a fishery. This will ensure that a few 

 compact beds of oysters are left at the conclusion of fishing opera- 

 tions. But since these oysters have already been spawning for at 

 least two years, and since so far as one can determine their fertilitj' 

 wanes after they reach a " fishable " age, the advantage of estabUsh- 

 ing these reserves is probably overrated.* At any rate, so long 

 as other beds of young oysters are known to be on the banks 

 there appears to be no need for establishing breeding areas on any 

 particular paar. If this be so , it would seem that the only time when 

 the estabhshment of breeding reserves would be necessary would be 

 when whole banks showed signs of approaching barrenness. But 

 as a matter of practice it would be unwise in the immediate future 

 not to take every conceivable precaution, and it would be regrettable 

 not to test the value of the breeding reserves as a means of arriving 

 at some solution of the main problem, namely, the recurrence of 

 barren years. So far as I am aware, no such measures have yet 

 been taken. f 



Both Herdman and Hornell were strongly of opinion that cultching 

 should be carried out, but so far as one is able to judge, Southwell's 

 criticism of this suggestion is a sound one. If Southwell's figures 



* Since so little is known of tlie spawning periods and the life-history of the 

 oyster, such a conclusion as this may have to be modified as our knowledge of 

 the subject increases. 



t It is pointed out later that the breeding reserves will be valueless if 

 spawn produced is carried off the banks. 



2f 6(7)12 



