Figure 7.— Percentage of the total annual catch of 

 Atlantic menhaden which were 0-. 1-, and 2-year olds 

 (solid line) compared to the average age of fish in the 

 catch (dashed line). 1955-68. 



North ATiantie- 



..-:«- Middli Adonhc 



AGE (YEARS) 



Figure 8.— Average weight of Atlantic menhaden by 

 fishing area, both sexes combined, 1955-68. 



slows down (Fig. 8). Not only are menhaden 

 caught in the northern fishery older, but they 

 are larger for any given age. Thus, the average 

 weight of age-1 fish in 1955-68 was 73 g (2.35 

 oz) in the South Atlantic Area, 136 g (4.37 oz) 

 in the Chesapeake Bay Area, and 214 g (6.88 

 oz) in the Middle Atlantic Area. Some indica- 

 tion of the relation between weight and length 

 for menhaden can be obtained from Figure 9. I 

 did not compute a similar curve for males, but 

 they do not appear to be as large as females 

 (Reintjes, 1969), at least for the older ages, but 

 whether there is a consistent difference be- 

 tween sexes, between years, and between fish- 

 ing areas has not yet been examined in detail. 



LENGTH (INCHES) 

 2-5 5^0 7.5 10.0 



—1 1 1 r- 



Y ■ 000014 X^ 



100 200 300 



LENGTH (MILLIMETERS) 



Figure 9.— Length-weight relation of female Atlantic 

 menhaden, 1962. 



Since there is such a differential distribution 

 by age and by size throughout the Atlantic 

 menhaden fishery, it is difficult to calculate a 

 single growth equation that will apply to all 

 areas. Nevertheless a plot of (weight)-'-/^ in 

 year t against (weight)l/3 in year t + 1 gives a 

 fairly good straight line relation for all areas 

 combined, indicating a rather consistent rate of 

 growth for all Atlantic menhaden. A prelimi- 

 nary calculation of a von Bertalanffy growth 

 curve for all areas combined gives Wt^^ = 

 1193.9g, k = 0.20 and Iq = -2.39. 



Not only has the abundance of Atlantic 

 menhaden declined markedly in recent years, 

 but there also have been conspicuous changes 

 in the apparent growth of fish from the 

 different year classes. Since about 1961 almost 

 all ages of menhaden caught have been con- 

 siderably larger than average, and the fish were 

 particularly small during 1957-61. Whether the 

 increased growth is due to a smaller number of 

 fish, improved growing conditions, or both, is 

 not known. It is obvious, however, that the 

 decline in the catch of Atlantic menhaden 

 would have been even more drastic if this 

 significant increase in the growth of the fish 

 had not occurred. Additional details on 

 changes in growth can be found in the 

 Appendix. 



