402 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 3 



YEARS 



OF 



LIFE 



Fig. 10. — Average rate of growth of golden shiners in Onized Lake and in the Huron Rive 

 at Ypsilanti, Michigan. 



Also in fig. 10 is shown a second curve 

 based on female golden shiners collected 

 and aged by Cooper (1936). These fish 

 were taken from the Huron River at Ypsi- 

 lanti, Michigan, May 19, 1934. Coop- 

 er's data, summarized in table 31, offer 

 evidence that the females of golden shin- 

 ers live to a greater age and grow some- 

 what faster than males, and suggest that 

 females predominated among the larger 

 shiners in Onized Lake. 



In Onized Lake, the first-year growth 

 rate was essentially the same as in the 

 Michigan collection of Cooper. How- 

 ever, Onized Lake shiners continued to 

 grow at a rapid rate during the second 

 year, while the rate of growth of the 

 Michigan fish was much slower. Probably 

 because of competition with other young 

 fish, Onized Lake shiners grew less rapid- 

 ly in their first year than might normally 

 be expected in the southern part of 

 Illinois. 



The origin of the Onized Lake golden 



shiners is unknown. Possibly they wer 

 stocked as forage for bass. Or they mai 

 represent escaped bait. 



Miscellaneous Fish 



One carp, one common sucker and on 

 blunt-nosed minnow were taken in thj 

 1941 census. i 



This miscellaneous assortment of roug j 

 and forage fish probably represents bai 

 that escaped the hooks of fishermer 

 Onized Lake is some distance from othe 

 water containing a variety of fish, and i 

 is improbable that these fish were carrie 

 to the lake by fish-eating birds. 



Age Distribution of Fish 



The overfished population of Onize 

 Lake was of particular interest from tl 

 standpoint of its age composition. As mjj 

 be seen from table 32, overfishing tende 

 to limit the life span of the fishes to tl 



