which na^ continue throughout the suamer, voxies in intensity end may have several pro- 

 nounced maxima. The occurrence of these periods is of great practical significance, "because 

 the production of seed can he naterially increased hy providing suitable clutch at the right 

 time and in the right places. 



The studj' of setting may he easily undertaken "by a competent marine hiologist 

 hy usins: vrire hag collectors (snail hags made of chicken v/ire, filled v/ith clean oyster shells) 

 placed at various stations or suspended at different levels from floats anchored in selected 

 locations. Ea,ch hag should he replaced at leapt once a week and its contents e3renined. In 

 this \-iair the intensity of setting, its exact time, and the optimum zone of setting at various 

 depths can he accurately established. 



If such experiments are sxiccessful and a sufficient number of young pearl 

 oysters are obtained on collectors, they can be transplanted to different experimental grounds 

 to determine the rate of growth of oysters and to study the factors controlling the prod\iction 

 of pearls. 



The formation of pearls has been the subject of many investigations, and 

 various factors responsible for the development of a pearl, such as mechanical irritation 

 or presence of parasites, are more or less understood. We do not know, however, why oysters 

 on certain grounds abound in pearls, while on others the pearls are almost lacking. For 

 instance, there are many places in Venezuelan waters which abound in pearl oysters, but the 

 latter contain no pearls. Detailed ecological studies are necessary for the understanding 

 of local factors v;hich favor the formation of pearls on certain grounds. 



Critical study of ecological factors responsible for the production of pearls 

 maj' lead to considerable improvement in the quality of natural pearls and to the increase 

 in their abundance. The aim of the proposed plan should be the finding of practical methods 

 to increase the poptilation of pearl oysters by facilitating their natural propagation, and 

 to encourage the production of pearls by selecting the grounds most suitable for this purpose. 

 The apT5lication of such a method may greatly increase the yield of the fishery and decrease 

 the fishing effort because oysters will be taken from more densely populated areas and only 

 from the grounds known to be highly productive in pearls. 



In planning this type of vrork, it is essential that certain grounds be closed 

 to the fishery and set aside for experimental purposes to determine the rate of growth of 

 young oysters, to carry out experiments with transplantation of seed oysters, and to deter- 

 mine their mortality rate. Studies 'of the rate of development of pearls, and of the percent- 

 age of oysters containing them, as well as the investigation of other factors, such as diseases, 

 effects of parasites, and attacks of various enemies, can be conducted simultaneously v;ith 

 the observations of oyster biology. Experimental grounds should not be large, so that their 

 ests.blishment v/ould not materisilly interfere with fishing operations. It is, hov/ever, in^. 

 portant that the selected grounds be v/ell patrolled to prevent unauthorized fishing, which 

 may ruin the experiments. 



Under the present system of management, and barring unforeseen circumstances, 

 the pearl oyster fishery around Margarita Island is expected to continue with occasional 

 interruptions v/ithout danger of serious depletion. But as long as the fishery is based on 

 the ex-oloitation of natiiral oyster ground s and depends entirely on natural repopulation of 

 oyster banks, it cazinot keep pace v/ith the increased intensity of fishing. In order to mini- 

 mize the effects of frequent interruptions, caused by insufficient supplies of oysters, and 

 to assure greater stability of the fishery, the present system of adjustment of fishery 

 efforts to the existing supply should be gradually changed to a system of cultivation of 

 pearl oysters, or oyster farming. Before such steps are undertaken by the Administrator of 

 Fisheries, several important phases of pearl oyster biology and ecology, discussed above, 

 itiu«t be elucidated by competent biological investigations. The program of such studies may 

 be briefly outlined as follov/st 



1. Survey of the principal pearl oyster grounds. Determination 

 of the areas ajid density of oyster population of each zone. 



a. Ecological characteristics - depth, character of bottom 

 and sea v;ater, currents, organisms associated with pearl 

 oyster, and enemies of pearl oyster. 



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