48 



the spawning season, and be free from other species of 

 fish. 



SELECTION AND INTRODUCTION OF BROOD STOCK 



An operator selecting brood stock must bear in 

 mind that the male chub grows larger than the female; 

 that the mature male is dist ingui shable from the female 

 by the presence of bony protuberances (horns) on the 

 head immediately before and during the spawning season; 

 and that the male is usually highly colored during the 

 spring, having tinges of red on the paired fins and 

 abdomen. In contrast, the adult female is generally 

 smaller and more drab in color than the male and has a 

 swollen abdomen during the spawning season. Results 

 of Michigan studies in the selection of brood stock 

 indicate that it is advisable to use 6- to 8-inch males 

 and 5- to 6-inch females for breeders. If larger males 

 (7 to 10 inches in length) are available and the total 

 stock could be represented by fish of this size, results 

 should prove satisfactory. Likewise, if larger females 

 ( 6 to 8 inches in length) are available, they could also 

 be used. It is not advisable to mix small {5-inch) 

 mature males with larger (10-inch) males in the same 

 raceway, as sizes thus mixed are not suitable and mor- 

 tality occurs as a result of fighting. Where small 

 (3-inch) females were mixed with larger (8-inch ) females 

 in the same raceway, a prolonged spawning season oc- 

 curred, resulting in a loss of fry. The larger females 

 matured about 2 weeks earlier than the smaller ones: 

 by the time the latter were through spawning, many fry 

 had hatched and emerged from the earlier- formed nests. 

 The presence of fry in the raceway and base pond before 

 the brood stock is removed, naturally complicates their 

 removal. 



One more suggestion to be presented at this time 

 concerns the age of adult fish. Normally only a few 

 pond-reared creek chubs can be expected to mature in 

 their first year and to be used as breeders. In the 

 second year, possibly 50 percent willmature (depending 

 upon the rate of growth, the larger fish being the most 

 favored); as a result, most of the brood stock will 

 have to be selected from older fish. Innatural waters, 

 female creek chubs normally do not mature until their 

 fourth year and mal-es not until their fifth. It is 

 evident that creek chubs are not long-lived fish, 

 rarely exceeding 6 or 7 years. 



