10 CEYLON PEARL OYSTER REPORT. 



" Where ' foul ' areas are found, i.e., where Sponges, Corals, Alcyonarians, Echino- 

 derms and Ascidians abound, as on many parts of the Western Cheval and Muttu- 

 varatu paars, the oysters, while numerous enough, are stunted and poor, suffering by 

 competition with the host of creatures living upon the same diet of microscopical 

 organisms. The only means of cleaning such a bed is to dredge it thoroughly, 

 separating and removing the materials brought up." 



On the Ceylon pearl banks the beds are too extensive to permit of dredging being 

 undertaken with this sole object in view, but as this cleaning can and should go on 

 concurrently with the dredging of spat for transplantation or of mature oysters for 

 sale, we have herein an additional argument in favour of taking up dredging on 

 a scale of considerable magnitude. We must not lose sight of the fact that dredging 

 has a fourfold utility, namely, (a) in fishing oysters, (b) in cleaning the ground and 

 removing enemies, (c) in thinning out overcrowded beds, and (d) in spat transplanta- 

 tion. Its value is not properly 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 

 star-fish destroyed probably means scores of oysters saved from destruction ; every 

 Cliona-rlddled 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 left 

 unchecked, and if fungoid and insect pests be ignored. 



Beacon Marks. Sir William Twynam has pointed out the need of fixed, well- 

 defined landmarks from which bearings may be taken at all parts of the banks ; and 

 he states his belief (p. 20 of his 1902 Report) that this want of adequate landmarks 

 resulted in the wrong bank being fished in 1836 two beds of young oysters being 

 fished instead of the one proposed. Again be states that the fishery of 1860 on the 

 Modragam was all but lost for the same reason a long continued search of 3 days 

 being necessary before the bed was re-discovered. 



A notable advance was made this year by the erection of a permanent beacon on 

 the tail of Karativo shoal, immediately to the south of the South Cheval Paar, to 

 serve as the point of departure at the inspection of the whole Cheval area. Many 

 years ago (1878) Captain Donnan sank an iron tank close to this spot and subsequently 

 (1883) he added a second. It was his custom at the beginning of each inspection to 

 locate these tanks by bearings taken from Kudiramalai and by means of the inspection 

 divers, and, when found, to mark the position tenqjorarily during the inspection by a 

 large beacon buoy the so-called shoal buoy. 



Captain Donnan's successor, Captain Legge, appreciating both the loss of time 

 involved in the oft recurrent hunt for sunken tanks, and the danger of taking 

 incorrect bearings when these tanks could not be located, requested sanction to have 

 a permanent beacon erected. This was granted, but all efforts to erect it last year 



