liKI'Oirr OF COMMISSIONER OF FISH AND FISHERIES. 31 



The industry is discussed by Dr. Dean separately for each country, 

 comprising in each case an account of the distribution and character- 

 istics of the natural beds, of the methods employed in cultivation, in 

 the production of seed and the rearing to adult size, and of all other 

 matters bearing upon the subject of oyster production and i)reserva- 

 tion. The importance of the suggestions contained in this report, as 

 well as in the preceding one, can not be overestimated, and it is sin- 

 cerely to be hoped that the oyster interests of this country will be mate- 

 rially advanced thereby. Some of the more significant of Dr. Dean's 

 conclusions are quoted herewith: 



It would appear, for example, that the degree of density of the water is one of 

 the most important factors influencing the spawning and fattening of the oyster. 



* * * The density of the water recorded in the best spawning-grounds of the 

 French coast is practically that of the spawning-grounds of Italy and of northern 

 Europe. * * * The specific gravity of the water in regions of maximum pro- 

 duction throughout Europe appears to bo uniform at about 1.023 in the case of the 

 "flat" oyster {Ostrea editlis), and at about 1.021 in the case of the Portuguese species 

 (Ostrea angitlata). The influence of warmth is not to be underestimated in regard 

 to the time and degree of spawning. 



The amount of spat occurring annually in a region appears to be directly in pro- 

 portion to the number of spawning oj'sters in that region. This is by no means a 

 novel suggestion ; it is one, however, that has been repeatedly impressed upon the 

 writer. The older idea, i t will be remembered, is that banks can never be exhausted, 

 ou the ground that the few oysters left by the dredgers will, by the annual spawning 

 of several millions of young, cause a very rapid regeneration. That the banks regen- 

 erate is true, but the process is shown to be slow and beset with many difficulties. 



* * * It should be noted that only in those places in Europe where the natural 

 bulk of spawning oysters is actually maintained does a great quantity of spat occur 

 regularly; also that where the number of spawning oysters is equal, the percentage 

 of spat will be notably greater if the spawning oysters are little disturbed. 



The amount of oyster food appears to be notably characteristic of a locality whose 

 normal food value is represented by conditions of warmth, density, and richness in 

 the organic and inorganic salts, which serve to rapidly generate the oyster-food 

 organisms. Should this natural food value of a locality be a high one, culture has 

 demonstrated empirically that the number of oysters that may be reared is exceed- 

 ingly great. It would appear that the number of oysters to be fattened is directly 

 proportioned to the food normal of the locality and to the volume of water which 

 passes over the bed. The actual size of a natural oyster bed is limited by other 

 reasons than that of a failure of the food supply in the neighborhood. * » *• 



The system of stated oyster reserve has been the key to the success achieved bj'^ 

 the French and Dutch industries, and has alone rendered it possible for these two 

 countries to sui)p]y the entire seed market of Europe. To obtain seed oysters by 

 collectors is shown to be possible only when a regular yearly fall of spat is thus 

 assured. Proximity to a large stock of spawning oysters is one of the imperative 

 conditions of artificial production, a condition that has been too often lost sight of 

 in experiments made along the Atlantic coast of the United States. Collectors in 

 Europe are placed on no river bank or sunk in no stream save where the culturist is 

 fairly sure of a set that will be at least profitable. If experiments in artificial pro- 

 duction are to be made in the United States, the suggestion given by Eurojieau oyster- 

 culture is to secure for the purpose a particular part of beach, near the line of low 

 water, where spat has been found to regularly occur. If a trial demonstrates that 

 the locality is favorable, the European culturist would then gradually and carefully 

 expend his money in the purchase or preparation of a luore extended area for collect- 

 ing and would study to provide the most suitable form of collector. * * » 



