FISH-CULTURAL PRACTICES IN THE BUREAU OF FISHERIES. 



753 



3,0(X),ooo fry. It is customary to take from 12 to 15 cans of fry in addition to 

 those taken in the well, the fry in the cans being the first planted. 



On vessels having no wells, aeration for all species of the marine fry, includ- 

 ing the lobsters, is accomplished by siphoning off and dipping the water freely, 

 as will be described for whitefish, pike perch, etc. For tempering the water 

 ice is suspended from the cover of the can in a cylinder. 



Temperature is a most important consideration in the transportation of 

 fishes, and owing to the different conditions under which they are hatched in 

 the various localities, is a feature that requires skilled discretion on the part of 

 the attendant. The general rule is to keep the temperature at least as low as 

 that of the water from which the fish were taken, and lower if the species is not 

 sensitive to changes. 



The maximum number of fishes to be carried most advantageously in a 

 lo-gallon can is another equally important question. The distance to be trav- 

 eled partly prescribes this number, but must be considered also with reference 

 to the temperature; and these factors, interdependent as they are, go to prevent 

 the formulation of any hard and fast rule. In the following table, however, 

 attempt is made to generalize by means of average conditions, and show the 

 number of fishes of specified kind and size as ordinarily transported in a 10- 

 gallon can. The cooler period of the year in which handled accounts for the 

 lower temperature for fry of the trouts as compared with the higher temperature 

 of fingerlings. It also accounts for the lower temperature for landlocked salmon 

 fingerlings as compared with fry. Ordinarily if landlocked salmon, rainbow 

 trout, and brook trout fry from the same source should be distributed in warm 

 weather it would be desirable to reduce the water temperature for the brook 

 trout considerably lower than for the other two species. 



Number of Fishes of Given Kinds and Sizes to be Transported in a io-Gallon Can under 



Average Conditions. 



