78 Carrying Capacity, Productivify, and Growth 



ton) for thin, a\orage, and fat fish that Thompson and Bennett found 

 for lUinois fish of those species. 



Condition Factor of Cooper and Benson. Still another method of 

 figuring condition is that of Cooper and Benson -^^ 



Coefficient of Condition, R = ^, ■ 



Where W = weight in grams, and 

 L = total length in inclics. 



This mixed method of fi^urins^ condition \\as used on small trout con- 

 venientlv weighed in scrams, whereas measurino; boards were calibrated in 

 inches and tenths. 



Conversion was as follows: to the English system (CF.), R X 22.038 

 — C.F.; to the Thompson and Bennett system, R X 2.2038 — C. 



Condition Cycles 



Some fish species follow c\cles of condition associated with seasons. 

 For example, the bluegills in a pond in central Illinois *^ showed high 

 condition during Ma\' and earlv June at the beginning of the spawning 

 season, follo\\od b\- a gradual chop in condition throughout the summer 

 and fall until a low point was reached in October or No\ember. Over 

 the winter, the condition gradualh" rose, but the most rapid rise took 

 place in earh' spring, during the months of March, April, and Ma\-, when 

 bluesiills were feeding hea\il\' on dipterous lar\ae and cladocera. Some 

 of the loss in condition of bluesfills, boiiinnins; in late Mav and extend- 

 ine throushout the summer \\as undoubtedlv associated with the lonff 

 spawning season of this fish, which began in Mav and extended into early 

 September. 



A seasonal condition cvcle for white crappies in a lake in the same 

 region-^ was quite difierent from the bluegill cycle of condition. Lake 

 Decatur ( Illinois ) crappies of 6 to 8.5 inches usually showed their highest 

 condition in the fall and winter, and the condition of these fish dropped 

 sharph" from earlv spring to June or July. Following a low point, usually 

 in Julw the condition of the crappies began to rise in August and con- 

 tinued to rise until winter. 



Several studies on condition in largemouth bass suggest that these 

 fish show no seasonal cxclo of plumpness. There is e\idence, however, 

 that the average condition of a bass population may change rather sud- 

 denlv with changing feeding conditions. For example, in 1941 at the 

 time of an extensi\e natural die-ofi" of die pond weed, P. foUosus, in a 

 pond,*' the bass had an average condition of 5.00. After the plant die-oft' 

 beo-an, thev became verv fat and their average condition rose to 6.15. 



