REPORT OF COMMISSIONERS OF INLAND FISHERIES. 143 



growths. In one a large percentage will survive, while in the other 

 the mortality will be high. The main cause will be the difference 

 in the current of water. 



By the angle of the paddle the amount of current is determined, 

 and the current determines the amount of food which is accessible 

 to the lobster, the extent of cannibalism, the ease with which they 

 molt, the amount of diatoms and other parasitic growths on the fry, 

 and those undeterminable factors which go to make up conditions 

 of health and vigor. 



That the proper amount of current should affect the accessibility 

 of the food and to a certain extent prevent their eating one another 

 is easily seen. That it should have an influence on the ease of 

 molting is also apparent. When the lobster molts it is, for a short 

 time, more or less helpless. A strong cvirrent throws it against the 

 sides of the bag or forces it against the screenings. These conditions 

 naturally do not favor molting. On the other hand, if the current is 

 very weak, while it may be sufficient to keep an active larva moving, 

 yet when the molting period arrives the larva will sink to the bottom 

 and be rolled along with whatever food, silt, diatoms, and fungus 

 spores have collected there. The current must be so adjusted as 

 to prevent both of these difficulties. Why it should affect the 

 parasitic growths on the fry is not so easily seen. Because of the 

 current continually running in the bags, there can not help but be 

 a considerable collection of diatoms, etc., on the inside of the canvas, 

 and consequently in the water within the bags. The number in the 

 water within the bags, however, cannot be much greater than in 

 the water outside; at least not enough greater to explain the abundant 

 growths of diatoms which sometimes occur. The probability is that 

 the fry are infected with these organisms by their contact with the 

 sides of the bags. With a current great enough to continually 

 throw the fry against the sides of the bags, the opportunity for their 

 infection would be very great; while with a current of less intensity 

 the natural instinct of the fry to shun a white surface would prevent 

 this to a great extent. That this is actually the case is shown by 



