272 G. V. NncorsKii 



N. p. Makarova (1961) showed that, under conditions of starvation, the fat 

 carp consume to maintain their metabohsm comes first from the intestine, 

 then from the muscles and fmally from the gonads. During the period of 

 gonad development, the fatness in carp gonads undergoes less fluctuation 

 than the fatness in any other parts of the body. The same phenomenon was 

 noticed in some other fish (smelt, perch). This is an important adaptation, 

 which, in the case of starvation, preserves, for a long time favourable 

 developmental conditions for eggs in the body of the mother. 



THE COURSE OF SPAWNING 



An important adaptation to the self-regulation of fish population density is 

 the character of spawning and the mode of arrival of the spawners on their 

 spawning grounds. It was determined for some fish that the middle-aged 

 individuals of the spawning population possess the greatest reserve of yolk 

 in the egg and fat in the yolk. F. G. Martyshev (cited by Nikol'skii, 1953) 

 has shown that the diameter of the egg of common carp, the length of the 

 larvae at the moment of emergence, and the weight of the yearlings before 

 the autumn appear to be highest in fish of the mean age group (Table III). 



Table III. Size of carp eggs, embryos at the time of emergence, and of yearlings 

 before autumn [after F. G. Martyshev) 



Thus, in common carp, the most viable offspring, best provided with food 

 for the period of yolk feeding, are left by the middle-aged parents. A similar 

 picture is found in the Amur lenok (Brachymystax lenok Pall.). The changes 

 in weight of the egg of lenok with fish size are shown in Table IV, and it 

 will be seen that in lenok, as well as in common carp, individuals of the 

 average size in the spawning population have the largest reserve of yolk in 



egg- 

 In fish of the spawning population the relative amount of fat in the egg 

 changes with age. Thus in the North Caspian roach the largest reserve of 

 nutritious substances in the eggs is found in middle-aged fish; both in young 



