166 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Figure 5. — Scale from 5-year-old marked shad spawning for the first time. 



generation, and 15 had complete regeneration. 

 This group consisted of 56 first- and 14 second-year 

 spawners. Forty-three percent (6) of the males 

 and 14 percent (8) of the females were spawning 

 for the second time. Figures 5 and 6 illustrate 

 representative scales from 5-year-old marked fish 

 spawning for the first and second time. In figure 

 5 the fifth or last annulus is plainly visible, but 

 since it was laid down just prior to the spawning 

 migration, it is combined with the scale edge and 

 counted as one year. Fish spawning for the second 

 time (fig. 6) had first spawned in 1956 when 4 

 years old. Marked males averaged 17.6 inches 

 fork length and 3.2 pounds in weight. Marked 

 females averaged 18.8 inches, fork length, and 

 4.1 pounds in weight. 



MARKED FISH RECOVERED 1958 



From a study of pelvic fin sections and radio- 

 graphs it was determined that 40 marked shad 



were recovered in 1958. Age determined from 

 scale readings indicated that 39 fish were 6 years 

 old and one was 5 years old. The radiographs and 

 scale samples were re-examined and the above 

 findings confirmed. Therefore, an error of ap- 

 proximately 2 percent exists either in interpreta- 

 tion of radiographs or in age determination. 



The 39 marked recoveries included 16 males and 

 23 females, of which 11 had no regeneration of 

 the right fin, 9 had one-third regeneration, 10 had 

 two-thirds regeneration, and 9 had complete re- 

 generation. This group consisted of 13 first-, 18 

 second-, and 8 third-year spawners. All males 

 (16) and 43 percent (10) of the females had pre- 

 viously spawned. Sixty-two percent (10) of the 

 males and 35 percent (8) of the females were 

 sijawning for the second year, and 38 percent (6) 

 of the males and 9 percent (2) of the females were 

 spawning for the third year. Figures 7 and 8 

 are representative scales from 6-year-old marked 



