252 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



9400 r-j 1 | 



1 — r 



I l T 



i r 



t F 



919,000 



(9 



o 245,000 



a 



< 



x 



m 



u. 175,000 



O 



6 



z 



105,000 



TOTAL FISHING EFFORT 



o 



< < 



O o 



X U. 



. u 



o «»■ 



z 



1935 1940 1945 1950 



Figure 1. — Shad catch, fishing effort, and catch per unit of effort for the Connecticut River, 1935 through 1951 



did not differ significantly from the proportion of 

 returns of those tagged from pound nets. 



Using the tagging data to estimate the fishing 

 rate, where T equals the number of fish tagged, 

 and T c the number of tagged fish recaptured, the 

 estimated fishing rate is TJT, or 359/633, which 

 equals 56.7 percent. Assuming that the same 

 proportion of untagged fish present in the river 



was removed by the fishery, where iV equals the 

 total population and C equals the catch, the best 

 C 



estimate of iV is 



T c /T 



The total catch in 1951 was 



100,967 shad; therefore, the best estimate of total 

 population would be , .'. i or A 7 — 178,072 fish. 

 Since the estimate of N depends upon T, T c , and 



