1939 SPAWN AND HATCH 



The sex organs were examined and the degree of sexual maturity was recorded for most 

 of the fish removed from Fork Lake during 1939. The testes and ovaries of the largemouth 

 bass were somewhat enlarged, although the fish did not reach maturity. Testes were small 

 and translucent or white; ovaries were somewhat swollen, translucent or yellowish, but 

 without definite eggs. No indication of nesting activity was observed in bass. 



The 1938 brood of bluegills was sexually mature in 1939. In March, the gonads of 

 both sexes were small, but during April they enlarged rapidly. By the latter part of 

 April, males showed swollen, white testes and females had large, yellow ovaries filled 

 with well-developed eggs. The old breeder bluegills showed about the same stage of sexual 

 development as the 1938 brood. 



The condition of the gonads was recorded as follows: 



Immature. Testes of the males slender, translucent cords; ovaries of the females small, 

 cigar-shaped, translucent and grayish-pink in color. 



Poorly developed. Testes slightly enlarged, opaque and white; ovaries somewhat enlarged, 

 opaque, pale yellow and developing eggs presenting a granular appearance. 



Testes greatly enlarged, flattened, with wavy edges and opaque-white; ovaries 

 greatly enlarged, oval, with large, distinct, solid, opaque, yellow eg 



Snlarged. 



Spawning condition. Testes as above, but giving off milt, a watery white fluid, when 

 gently pressed; ovaries as above, but turgid, giving off eggs when gently 

 pressed. Eggs semillquid, translucent, brownish-yellow and sticky. 



Partly spent. Testes (after June) same as next above but less swollen; ovaries smaller 

 but very similar to condition described as "enlarged." It is assumed that 

 these fish have already spawned once. 



Completely spent. Males with testes small and pinkish; ovaries of females flabby at first, 

 contracted later, pinkish with granular appearance. 



The percentages of fish taken each month showing each of the above conditions of 

 sexual development are listed in table 13. In this table the sexes are separated and 

 figures representing males underlined. Males matured earlier than females, and slightly 

 more males than females were in spawning condition late in May. This lag in the develop- 

 ment of the females seems to continue throughout most of the simmer. In the collections 

 of September 18-22, one female was in spawning condition and one partly spent, while all 

 males were completely spent. The table indicates that the spawning period of the bluegill 

 Includes June, July and August. Observations on nesting confirm this Information. 



TABLE 13. —THE SEXUAL DEVELOPIWJT OF BLUEGILLS TAKEN FROM FORK LAKE, 

 1939, SHOWN AS PERCENTAGES. FIGURES REPRESENTING MALES ARE UNDERLINED. 



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