l66 MADRAS FISHERIES BULLETIN [VOL. XVI, 



The only means to clean a bed is to dredge it thoroughly, sepa- 

 rating and treating the materials brought up in the way above 

 described. 



The Indian banks are too extensive to permit of dredging being 

 undertaken with this sole object in view, but, as this cleansing can 

 and should go on concurrently with the dredging of spat for trans- 

 plantation or of mature oysters for sale, we have herein one of the 

 chief arguments in favour of taking up dredging on a scale of 

 considerable magnitude. Sight should never be lost of the fact 

 that dredging has four-fold utility, namely, (a) fishing oysters, (b) 

 cleaning ground and removing enemies, (c) in thinning out over- 

 crowded beds, and (d) spat transplantation. Its value is not pro- 

 perly assessed if account be taken of the first item alone or even 

 of the first and the last. 



Every live coral removed and replaced by a fragment of clean 

 cultch may mean the addition of three oysters at the next fishery ; 

 every starfish destroyed does mean scores of oysters saved from 

 destruction ; every Clione-riddled block of coral bleached on the 

 shore will tend to reduce the widespread havoc this inconspicuous 

 sponge causes amongst the oysters. The immense advantage that 

 accrues from keeping the banks in a state of thorough cleanliness 

 can well be appreciated by an agriculturist who knows how his 

 crops fall off if weeds be allowed to run riot unchecked, if fungoid 

 and insect pests be ignored, if the soil be never disturbed and if 

 sun and air be excluded therefrom. 



(d) Thinning out of oysters. — The evil effects attendant upon 

 overcrowding of the oysters which so often takes place upon 

 certain of the Indian banks have been laid stress upon, and I think 

 sufficiently demonstrated. The remedy suggested consists of 

 thinning out at suitable time. The dredge again is the only reme- 

 dial agent. Thinning out, transplantation, and cleaning the bank 

 may all proceed conjointly -the thinned out oysters being depo- 

 sited on unoccupied ground, while the foreign organisms and the 

 cultch materials will be taken ashore, the former to be destroyed, 

 the latter to be bleached. 



(V) 

 Creation of a Fisheries Department. 

 A Fisheries Department should be constituted under scientific 

 control and the work of inspection of the pearl banks and superin- 



