FISHERY BULLETIN: VOL. 85, NO. 3 



O 



li. 

 u. 



UJ 



O 



LU 



> 



< 



3 

 O 



1942 46 50 54 58 62 66 70 74 78 



YEAR OF FISHING 



Figure 5. — Cumulative fishing effort on Atlantic menhaden as a percent of total, by fishing area 

 for years 1941-81. (Data for 1941 through 1968 were adjusted (reduced) by Nicholson (1971a) to 

 compensate for the small size of vessels that frequently fished in that area. The data for the middle 

 Atlantic area were also adjusted, but to a lesser degree. Data from 1969 to 1981 are unadjusted. 

 North Atlantic area data, adjusted by the Nicholson (1971a) criteria, would probably be less than 

 half the amount shown, while the middle Atlantic area values may only be slightly reduced.) 



n 

 o 



X 



« 



z 

 o 



I- 

 o 

 cc 



I- 



LU 



5 



X 



o 



< 

 o 



800 



700 



600 



500 



400 



300- 



200 



1001- 



./■-.\ k 



'V 



\/ 



/ 



A 



aC^- — Age 5 + 

 ir~:^~^' Age 4 

 ^ ' ... Age 3 



-Age 2 



/-vA./' 



\ 



' ' . ' ' '. I ' I ;•'■;•-'■■' ■^--•i'-v---i--i-i -■'—■■-■'' ■<-■ 



1940 44 48 52 56 80 64 68 72 76 80 



-Age 1 

 -Age 



YEAR OF FISHING 



Figure 6. — Catch of Atlantic menhaden in thousands of metric tons by age group for 1955 



to 1981. 



SIZE AT AGE AND GROWTH 

 ANALYSIS 



It is necessary to derive two types of size at age 

 and growth estimates because of the seasonal dif- 

 ferential distribution of Atlantic menhaden by 

 age and size (Nicholson 1972, 1978). Parameters 



are estimated by area to characterize the seg- 

 ments of the population normally harvested 

 within that area and are estimated for the entire 

 fishery to characterize the harvested population. 

 Because relative harvest rates may vary among 

 areas between seasons, apparent area-specific 

 growth parameters are estimated for yield-per- 



576 



