An examination of the mean values for 

 dorsal soft rays and spines (table 12) shows 

 that the latter is high and the dorsal soft ray 

 count is low in the James sample. The reverse 

 is true of the York -Rappahannock sample and 

 the composite upper Bay sample is intermediate 

 for each count . 



On the basis of dorsal ray counts and with 

 due consideration for the differences in environ- 

 mental conditions which may occur at the same 

 locality from year to year and the slight increase 

 in mean values noted for some downriver samples, 

 there seems to be three subpopulations repre- 

 sented within Chesapeake Bay, namely Upper 

 Bay, York -Rappahannock, and James . 



A comparison of soft dorsal fin rays in 

 samples from the Hudson and James Rivers is 

 given in table 13 . A test shows the difference 

 to be highly significant at the one percent level 

 and indicates they very probably were not drawn 

 from the same population . Incidentally, the 

 mean values for these two river systems are 

 the lowest yet encountered for this character. 



samples could have been taken from the same 

 population. When these data are considered as 

 up- and downstream composite samples (table 4), 

 the slight differences in values are shown to be 

 not significant. Up- and downstream localities 

 in the Chickahominy River are compared (table 5) 

 and although there is a slightly greater down- 

 stream value it is not statistically significant. 

 Thus for anal soft ray counts within the James 

 River for the two year classes studied no signifi- 

 cant increase was noted for downstream samples. 



The distributions for samples of anal 

 soft rays for the 1954 year class from the Hudson 

 River are given in table 18 . A test indicates that 

 the samples very probably were not drawn from 

 the same population. When the data are arranged 

 in up- vs. downstream composite samples 

 (table 7), the mean value of the downstream 

 sample is higher and a test indicates a significant 

 difference which indicates that the two samples 

 very probably were not drawn from the same 

 population. The data for up- and downstream 

 samples of young taken in 1953 (table 8) give the 

 same result . 



Soft Rays in the Anal Fin - -The number of 

 anal spines is almost invariably three in young 

 specimens more than 25 mm . in standard length; 

 during development up to this size the third 

 spine is derived from a soft ray. Throughout 

 the range of the striped bass the modal number 

 of anal soft rays is 11 . The distributions range 

 from 7 to 13 rays, but 10 is the only other num- 

 ber which occurs frequently . When the mean 

 standard length of young specimens with 10 or 

 fewer rays was compared with that of specimens 

 having 1 1 or more rays (table 1) taken in the 

 James River in 1954, no statistically significant 

 difference was obtained. 



The frequency distributions of anal soft 

 rays in samples taken in the James River in 

 1955 are given in table 2. A test shows the dif- 

 ferences to be not significant and indicates that 

 the samples could have been drawn from the 

 same population . With the same data arranged 

 in up- vs. downstream composite samples 

 (table 3), there is only a slight difference in the 

 mean values which is shown by test to be not 

 significant. When tested the samples of the 1954 

 year class from the James River (table 14) show 

 no significant difference which indicates the 



In summary it is noted that the values 

 for downstream samples in the Hudson are sig- 

 nificantly higher than for upstream samples; 

 this trend is like that exhibited by second dorsal 

 soft rays . The slight differences again may be 

 due to average differences in environmental 

 conditions. 



The data for anal soft rays in samples 

 taken from several tributaries of Chesapeake Bay 

 in 1955 and 1954 (tables 19 and 20) exhibit moder- 

 ate differences in mean values for different year 

 classes. However, even the greatest differences 

 which are found in the Nanticoke (t = .976) and 

 the Wicomico (t = 1.49), are not significant at 

 the five percent level . 



When the different river systems are com - 

 pared for both year classes (tables 19 and 20) it 

 is obvious that the values for the James River are 

 lower than for all others . Tests show that the 

 samples very probably were not drawn from the 

 same population. When the James sample for 

 1955 (table 19) is tested against the composite 

 sample from the Elk to York, X 2 = 51 . 12 which 

 is significant at the one percent level and indicates 

 the two samples very probably were not drawn 



91 



