CATCH OF AGE-I (eiLLlONS OF FISH) 



Figure 34.— Catch of age-1 Atlantic meniiaden com- 

 pared to total catch of ages 0-3 bv year-class, 

 1955-67. 



seen readily. Although the total catch data are 

 not yet available for the 1967 year class, I have 

 listed the catch of age 1 fish in 1968 from the 

 1967 year class. This catch, 0.382 billion age 1 

 fish, would indicate a potential total catch 

 from the 1967 year class, through 1970, of less 

 than 1 biUion fish. 



Mortality Rates 



Mortality rates of Atlantic menhaden have 

 been estimated, although accurate separation 

 of natural mortality and total mortality is not 

 yet possible. On the basis of the catch-effort 

 data, mortahty curves (natural logarithm of the 

 catch per standard vessel day by age group) 

 were computed by year class for the five 

 fishing areas separately and for various com- 

 binations of the areas. The curves for the 

 Chesapeake Bay data and the total Atlantic 

 data are shown in Figures 35 and 36, respec- 

 tively. The mortality rate for the total Atlantic 

 data appears to be increasing in recent years. 

 The average mortalities calculated are listed in 

 Table 3. Since there is considerable interchange 

 of menhaden between the different fishing 

 areas and age groups are fished at different 

 levels of effort, I have combined the data for 

 the areas in various combinations to see what 

 effect this would have on the mortahty 

 estimates. These mortalities were calculated by 

 taking the annual natural logarithms of the 

 catch per standard vessel day for the years 

 indicated in Table 3 and computing the slope 



Table 3.— Estimated apparent mortalities of Atlantic menhaden, based on catch effort and age 

 data, by area. 



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