XXX.-CRAW-FISH CULTURE IN EUROPE. 



By H. Rubelius.* 



[From " Industrie- Blatter," seventeenth year, No. 31; Berlin; July 29, 1880.] 



The attempt to raise craw-fish artificially in inclosed waters is old and 

 has been made repeatedly, but so far none of the methods employed have 

 given entire satisfaction ; and at best it requires a number of years before 

 craw-fish culture becomes profitable. It is well known that the common 

 craw-fish, also called river craw-fish (Astacus fluviatilis, Bond.), is found 

 throughout nearly the whole of Europe, but especially in North Ger- 

 many, and that it changes its shell every year. The male craw-fish does 

 this generally in June or in the beginning of July, while the female com- 

 mences in July. During this period both the male and female craw-fish 

 are very tender, and many of them die. After the craw-fish has thrown 

 off its old shell, a very soft skin forms which begins to harden in a few 

 days. During this time great care must be taken of the craw-fish. The 

 boxes must not be overcrowded, but must be supplied with sufficient 

 food, of which at this time the craw-fish require a double quantity. 



The male craw-fish prefer to live together in large numbers in holes 

 high up the bank. The female stays in her hole (i. e., she always re- 

 turns by day-time to the same hole where she has been before) until the 

 young fry slip out of the eggs which are attached to the abdominal ap- 

 pendages under the tail. A medium-sized craw-fish has, on an average, 

 150 to 200 eggs, which are hatched in May. The young craw-fish re- 

 semble very small worms, and are for some time attached to their 

 mother's tail by fine threads. They are in this way protected against 

 the persecutions of their enemies, the eels, pike, perch, &c. 



Some time elapses before the little craw-fish venture out alone. After 

 a year's time they have reached the size of a wasp. They grow so slowly 

 that it takes three to four years before they have reached the length of 

 about 10 centimeters, when they can be brought to market as " soup 

 craw-fish." From the fourth to the sixth year they reach the length of 

 " medium craw-fish" viz, 12 centimeters. A full-sized " table craw-fish" 

 has a length of 15 to 18 centimeters, and is froin eight to twelve years 

 old. Their quicker or slower growth depends on the water, its temper- 

 ature, and their food. Lakes which are situated in moors and are sur- 

 rounded by mountains generally have warmer water than open lakes 

 and rivers, and are, therefore, more favorable to the development of the 



* Zur Erebszucht, von H. Rubelius. — [Translated by Herman Jacobson.] 



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