Growth 83 



4.0- 



m 



CD 



I 3.0 



gi 2.0 



1.0- 



10 fish per 

 acre-foot 



300 



800 



2800 " 

 4500 " 



6500 



30 60 90 



Days of Growth 



Figure 4.5. Relationship between growth and growing time in days of 

 small walleyes in ponds, showing population density in fish per acre-foot. 

 These growth curves are actually a measure of relative abundance of food. 

 [From Dobie, J., Prog. Fish-Cult, 18(2) (1956)] 



April, September, and October in waters several hundred miles north of 

 Norris, Tennessee, provided the water is above 60°F and an abundance 

 of food is available.^ The length of the growing season for fishes which 

 rather closely parallels the agricultural growing season, but is somewhat 

 shorter, limits the annual growth cycle to a definite period of weeks or 

 months (Figure 4.3). Tlie amount of growth actually taking place during 

 this time depends (within limits) upon available food resources. At one 

 extreme, a fish might approach the maximum rate of gain for a given 

 species in a location where food was abundant and the growing season 

 was less than 3 months; at the other extreme, a fish might remain at a 



