26 



advance of summer. In Europe the spatting season ranges from the middle of 

 June through July and on even to the middle and end of August according to 

 the character of the weather and the number of hours of sunshine. In Pulicat 

 Lake on the East Coast of India I find one spatting maximum occurs in 

 September and the beginning of October, while at Tuticorin where the tempera- 

 ture and salinity of the harbour waters are remarkably stable the whole year 

 round, the spawning of oysters is widely distributed throughout the greater part 

 of the year and brood oysters appear to met with during practically every 

 month. On the Sind Coast seasonal differences are much more distinctly 

 marked than on the South Indian Coasts where hot and cold weather seasons 

 are largely a figure of speech and not actualities. In Sind this is not so ; during 

 December, January and February a marked lowering of the temperature of the 

 inshore waters takes place, while an even more emphatic rise occurs in 

 July, August, September and October. A sudden alteration in the density of 

 the water is another factor which sometimes has a distinct influence in 

 accelerating or stimulating the emission of the reproductive products ; around 

 Karachi the heaviest rainfall of the year occurs in July ; in 1909, 3-29 inches 

 of rain fell in Karachi on the 14th, 15th, 26th, 27th and 29th July, the total 

 average annual fall being about 7 inches only. Hence it may well be that under 

 the combined stimuli of increase in temperature and a sudden decrease in salinity 

 at the end of July, this period of the year may mark the usual spatting maximum 

 in this locality. This is however merely a deduction based on knowledge of 

 what holds good elsewhere and I am prepared to find when we obtain further infor- 

 mation that the recession of the sea at the times of great spring tides during the 

 hot weather season have more to do with emission than have freshets. Exposure 

 to the sun's heat for a period of several hours daily on the occasions of those 

 spring tides which occur during warm weather acts as a distinct stimulus to the 

 reproductive glands of many littoral animals. I have noticed it of pearl oyster?, 

 edible oysters, and tube-dwelling worms (Sabellids), and it is a matter of 

 common belief among oyster-culturists that spatting takes place alwavs on a 

 rising tide. The dates when spring tides occur during the months of July, 

 August, September and October are the times when conditions are likely to be 

 most favourable to induce spawning in edible oysters on the Sind coast and this 

 is about all we can definitely say at present ; the size of the brood oysters seen 

 in Dumbri creek and at Shams Fir suggested their having been spawned during 

 September. 



108. The first experiments to be made should be directed to ascertain the 

 month of the maximal spat-fall and the factors which accelerate or retard the 

 emission of spawn locally. 



VI. THE REMEDIAL MEASURES PROPOSED. 



109. The recommendations which I shall now make for the improvement 

 of the Sind oyster industry fall into two divisions, (a) the administrative or 

 regulative aud (b) the cultural. With regard to the lack of success attending the 

 enforcement of the various regulations made for the protection of the Sind 

 oyster beds since 1897, those which enforced an annual close season and 

 closure of the creeks by compartments for two-year periods suffered from the 

 defect inherent almost always in such measures the omission to limit or 

 define the quantities to be removed during the open seasons. All the exist- 

 ing creek beds are very restricted in area and I have seen all the improvement 

 effected in the Dumbri and Mall creeks by two years of closure nullified by two 

 days' fishing upon the re-opening of the beds. It is not a matter of extending 

 the period of closure; it is the control of the beds when open to fishing which 

 is the essential of successful regulation. The object of closure is to afford 

 protection to the adults from undue depletion and to give them an adequate 

 opportunity to produce new generations. A little consideration will show that 

 it is obvious that the good effects of closure will be in inverse ratio to the 

 massing of the individuals to be protected. When the animals are sedentary 

 and massed thickly over small areas, close seasons are of little value ; the 

 shortest of open seasons will suffice for pract'cal extarraination if the subject of 



