u 



z 



u 



I I I I' I J ( — I I f I I — n~ 



N. 15.774 l\ SOUTH ATLANTIC AREA 



^^ AGE-OflSH ^^ AGE-2 FISH 

 g*^ flGE-IFlSM l??l AGE-SFISH 



^B AGE-4 AND OLDER FISH 



CHESAPEAKE BAY AREA 



N-36,S83 



MIDDLE ATLANTIC AREA 



NORTH ATLANTIC AREA 



N- 6.100 



NORTH CAROLINA 



1 ^ 1 IT 



^ 



ao 100 120 140 l«0 180 200 220 240 260 280 300 S20 340 360 



FORK LENGTH IN MILLIMETERS 



Figure 6.- -Length c»mposition of samples from 

 purse-seine catches, 1957. 



ranged from about 200 to 300 mm. and 

 fish of age 4 and older ages, which 

 ranged from about 280 to 360 mm. Fish 

 of age 3 were completely obscured in 

 the total length distribution. 



The lengths of fish in samples 

 from the North Carolina fall fishery 

 ranged from about 75 to 355 mm., 

 with those of older ages represented 

 by a dominant mode at 312 mm. 

 Age-0 fish accounted for the greatest 

 portion of the length curve below 

 230 mm. and comprised two size 

 groups, one with a peak at 92 mm. 

 and the other with a peak at 142 mm. 



As noted for previous years (June 

 and Reintjes, 1959 and I960), the most 

 obvious features of the 1957 length- 

 frequency curves were (1) the hetero- 

 geneity of the length-age groups in the 

 various areas, (2) the complete absence 

 of larger, older fish in the summer 

 purse -seine catches in South Atlantic 

 and Chesapeake Bay waters, (3) the 

 paucity of small fish in northern 

 waters, (4) the gradual increase from 

 south to north in lengths of fish com- 



prising the youngest age groups, 



(5) the occurrence in the fall fishery 

 off North Carolina of homologous 

 length groups represented in the sum- 

 mer catches farther northward, and 



(6) the recruitment of small, young- 

 of-the-year fish during the fall season 

 off North Carolina. 



Since differences in the nnean size 

 of males and females have been noted 

 in the previous reports in this series 

 (June and Reintjes, 1959 and I960), it 

 is of interest to examine the 1957 

 length distributions of each sex to 

 determine whether such differences 

 were sufficiently great to affect the 

 position of the modes in the unsexed 

 samples and thus, perhaps, make con- 

 clusions regarding changes in length 

 misleading. 



The curves in figure 7 show a 

 parallel size differential between the 

 sexes which became more pronounced 

 as length increased. With the exception 



I I I I I 



I I I I I I I I I 



SOUTH ATLANTIC AREA 



MALES 



-FEMALES 



CHESAPEAKE BAY AREA 



NORTH ATLANTIC AREA 



NORTH CAROLINA 

 FALL FISHERY 



° I i~T I 1^ I I — r 



SO 100 120 140 ISO ISO 200 220 240 260 280 300 320 340 360 

 FORK LENGTH IN MILLIMETERS 



Figure 7.--Length frequencies of males and females in 

 samples from purse-seine catches, 1957. 



12 



