One should not underestijnate the possibility to make practical use of certain rules 

 concerning maturity with regard to early spaiming, Karly feeders among the fingerllnga 

 of rainbow trout, for instance, are superior to others in many ways, such as better 

 acclimatization, longer growth duration, complete accomodation to food at the beginning 

 of the main period of growth during summer, less inclination to contract Cyrodactilua etc. 

 The differences are at times quite marked, 



I know of a trout hatchery in Central Germany. There, the brood (from Danish eggs) 

 began to feed on May 26, while brood frcai their own eggs began to feed already on April 1, 

 i.e. almost two months earlier. 



With regard to the appearance of sex maturity for the first time in individual fish, 

 I would like to say that two years old females bring forth eggs for the first time. 

 According to Wohlgemuth males can beocMne sex-mature already in the first year. 



If mature fish are not stripped or do not spawn, their eggs and spermatozoids are 

 converted back. The egg shells remain in the "ovarian pouch" and are expelled at the 

 next spawning. First year females are seldom fit for stripping, they are not large enough 

 and their state of nutrition is often under par. 



Certain paratypical factors play an in^rtant role in the evaluation of spawn trout 

 to be used for stripping. Size, state of nutrition and perhaps even age. These factors 

 influence the sex, the number and the growth of the progeny. The size of the parent fish 

 is the determining factor . Upon it depends: 



(1) The absolute and relative amount of eggs in the female and of milt 

 in the male. 



(2) The size of eggs. 



(3) The proportion of sexes among the progeny in relation to the 

 mating of differently sized parent fishes. 



Age and state of nutrition seem also to exert some influences, although to a lesser 

 degree. They will influence the procreative functions of males and females. Young males, 

 3 to -i years old, subsisting upon natural aliments will produce a better milt, according 

 to Scheuring. than older ones. These latter are frequently sterile. Tfell nourished 

 males — even those subsisting altogether upon artificial food — produce more milt than badly 

 nourished ones. 



Diseases and in.luries are injurious to both, males and females, A more than normal 

 loss of scales may cause sterility in females and may cause water disease of the vitelline 

 sac of their brood. Injuries through fishhooks, though, have no noticeable bad results. 



All of these things have to be considered if first class spawn-trout is the attempted 

 goal. 



Females of 1 kilogram weight produce an average of 2,000 eggs. In smaller fishes, 

 the number of eggs is offhand absolutely less but relatively greater. In very small 

 females, their number drops absolutely as well as relatively, as may be seen from table 

 13. The figures in this table come from well nourished trout, raised by me at the 

 Academy of Eberswalde. 



102 



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