TROUT WATERS AND CARP WATERS 



coefficient of respiration, about half that of the trout, 

 makes them extremely sensitive to low temperatures, 

 and this weakness of internal oxidization prevents them 

 from resisting such extremes. In autumn, when the 

 water goes down to about 50 degrees Fahrenheit, 

 most of them cease to feed. Even if they absorbed 

 nourishment, they would not be able to digest it, for 

 the digestive juices and their diastases would not be 

 able to function. Yet at the same temperature the 

 trout are both agile and voracious. When the tem- 

 perature is still lower, the fish seeks a shelter or falls 

 to the bottom in a condition of lethargy. It hiber- 

 nates. Its life is suspended. It will return later, 

 in the spring, when the waters are warmer again. 

 Then, with the progressive rise in temperature, life 

 will begin again; the fish will get up, begin to look 

 for food, and carry on its vital activities. Hibernation 

 is over. 



We find an interesting contrast in fish-breeding 

 establishments. The trout ponds are as animated as 

 ever in winter. It is the spawning time, when fish 

 are chosen to breed from, a time for artificial fecunda- 

 tion. The fish which are not yet ready to spawn are 

 fed and continue to grow. Though the weather is 

 cold, they go on seeking prey, and they swallow it 

 greedily enough, though digestion, at these low 

 temperatures, is not always complete. Carp ponds, 

 on the other hand, have a very different story to tell. 

 In the largest of them, the winter is the fishing season, 

 the time when the fish are sent to market and eaten; 

 but in the smaller ones, containing the smaller speci- 

 mens, it is a period of rest. The carp do not feed 

 and do not move. During the winter months, there 

 is no sign of life in them. Many carp raisers have 

 special narrow, deep tanks, filled with cold water 

 continually renewed, in which the carp, taken out of 

 the ponds, are placed to pass safely through the 

 winter season. Their lethargy permits of their being 

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