The Distribution of Senescence 



1953), Fig. 15fl, b. In the goldfish, according to exhibition 

 breeders, fertility reaches a maximum under aquarium condi- 

 tions in the third year of life, declining thereafter, and almost 

 all fish are sterile by the seventh year. Breeding at 10 years is 

 recorded (Hervey and Hems, 1948). When the reproductive 



3000 



2500 



2000 - 



1500 



1000 



500 - 



10 



20 



11 

 22 



12 

 21 



13 A b ram is drama 

 26Acipenser stef/afus 



12 3 15 6 7 8 

 2 1 6 8 10 12 11 16 



Age in Years 



Fig. 17 (b). — Growth in weight of the sturgeon (Acipenser stellatus) and the 



bream (Abramis brama). Scale for A. stellatus 1 Russian lb = 100. Scale for 



A. brama 1 g. = 1 (after Schmalhausen, 1928). 



life is over, however, the fish may improve greatly in condition, 

 and appear much less sensitive to environmental damage than 

 before. In exhibition fish the life-span appears to be about 

 1 7 years, though much older examples are known. The extreme 



73 



