8 U. S. BUREAU OF PISHEBIES. 



Table 3. — Grmvth records of Lepomis humilis from Iowa and Louisiana.^ 



1 The cause of the apparently undue fluctuations in average lengths over a given growth year is attribut- 

 able to the method of computation and to the accidental occurrence of a number of especially well grown 

 or poorly giown fish in the collections of certain months. 



Figure 4 indicates the growths of the simfish under the different 

 climatic conditions of Louisiana and Iowa. The figure also points 

 out the periods of ripeness of fishes of different seasonal birth. It 

 may be noted that the growth of the sunfish over four years of its 

 life is not especially slowed down, even though the fish reached 

 sexual maturity in the second year. The usual circumstance — ^that 

 the attainment of sexual maturity is accompanied by a considerable 

 retardation of growth — is not strikingly borne out in the average 

 curve of growth of this species (Fig. 4). A breeding female 3 cm. 

 long may triple her size within four years. The curve of growth 

 (Fig. 4), rising at an angle of 40° or more and sustaining its direction 

 quite into the fourth year, indicates the ability of the fish to obtain 

 and utilize in growth an increased food suppljr even after the attain- 

 ment of adulthood, determined by sexual activity. The growth of 

 this sunfish stands in contrast to that of the smallest representative 

 of the family Elassoma, whose growth (Barney and Anson, 1920) 

 after reaching sexual maturity at the end of the first year of its life 

 is very markedly slowed down. It is not to be understood, however, 

 that the ripening of the sexual organs of humilis occurs without ex- 

 pense to growth. The curve of growth (Fig. 4) is based on averages 

 obtained from the measurements of large numbers of fish of both 

 sexes. The facts that the breeding season is not a limited one and 

 that spawning fish may be taken in any summer month along with 

 large numbers of spawned or ripening fish have a tendency to smooth 

 out the growth curve. Irregularities of growth of individual fishes or 

 sexes are masked, because of the length of the breeding season and 

 the varying time of attainment of sexual maturity and because of the 

 process of computation used to secure the points on which the growth 

 curve is founded. The difference between the growth of Elassoma 

 and that of hmnUis is that the retardation of growth of Elassoma 

 after sexual maturity is permanent and increase in size of this species 

 thereafter is at u very slow rate, whereas in humilis the retardation 



