21 



spawn from each bed but it appears that ordinarily no suitably 

 clean cultch is available to attract fresh spat. Only when some 

 of the adult oysters now living shall die off iu the next great 

 drought will suitable cultch be provided to meet the taste of 

 the swimming spat which must have clean surfaces for attach- 

 ment or they will die without making attachment. Shells 

 covered with mud and diatom slime are valueless as cultch ; 

 at the present time practically all the oysters now alive in 

 Pulicat lake are in such condition. 



If this method of oyster-culture be adopted, additional area 

 may be obtained by planting up the muddy shallows with 

 mangroves and by inducing oyster spat-falls upon the stilt 

 roots thrown out by these bushes. In some districts mangrove 

 oysters are of considerable economic importance ; the culture 

 is most simple and it would have other advantages. At present 

 the mangrove is all but absent from the lake ; its introduction 

 would help to accelerate the silting up of the muddy shallows 

 east of Venadu. It would in this way reduce the area of the 

 water-spread of the lake at its shallowest part and so reduce 

 that excessive evaporation which in dry seasons brings about 

 all the difficulties resultant from the partial drying up of the 

 lake. Yet another advantage would be the supply of large 

 quantities of bark for net-tanning which would be thus pro- 

 vided for the fishermen — mangrove cutch being probably the 

 best barking material known for nets. Its collection and pre- 

 paration form a considerable industry in Burma and in Borneo. 

 In passing I may also mention that I have seen mangrove 

 purposely planted along the shores of a muddy bay on the north 

 coast of Kattiawar to furnish supplies of firewood. 



Karimanal inlet is the only place where continuous culture 

 is possible. Eeceiving more tidal water than any of the other 

 localities where oyster beds are situated, its oysters may be 

 expected to show the best growth ; against this advantage is to 

 be set comparatively limited area. The west side only is 

 available for culture, the east side being exposed to silting 

 and shoal movement in consequence of the manner in which the 

 bar shifts gradually from the south to the north end of its run 

 during the years it remains open. 



If culture be worked in three to four-year periods, all 

 oysters save a large breeding reserve in deep water being 

 harvested just before a closure of the bar, then the area 

 available is of very considerable extent— not less than ten 

 square miles at a moderate estimate. 



The most suitable plan of operations would probably be to 

 prepare by liming a great quantity of cultch — old oyster and 



