from the same population. In a similar test 

 for the 1954 sample (table 20) comparing the 

 James sample with the composite sample from 

 the Choptank to the York, X 2 = 39.72 which is 

 significant at the one percent level and indicates 

 probable heterogeneity . 



When arranged in composite samples 

 representing the East Shore, West Shore (James 

 River excluded), and the James River in table 

 11, it is obvious that the latter sample differs 

 and a test indicates that they very probably 

 were not drawn from the same population . The 

 West Shore sample differs slightly from that of 

 the East Shore but there seems to be no biolog- 

 ical significance . 



The Chesapeake Bay samples are arranged 

 in four geographic groups from north to south 

 in table 12 . The James sample is obviously 

 different from each of the other three composite 

 samples and a test indicates that the four 

 samples very probably were not drawn from the 

 same population . 



In summary the results from an analysis 

 of anal ray counts of Chesapeake Bay samples 

 indicates the presence of two subpopulations . 



A comparison of the anal soft rays of 

 samples from the Hudson and the James Rivers 

 is given in table 12 . The two samples are sig 

 nificantly different at the one percent level and 

 very probably were not drawn from the same 

 population. An examination of the data in tables 

 13, 19 and 20, show that the Hudson sample is 

 differentiated from other Chesapeake populations 

 at a higher level than it is from the James 

 sample . 



DISCUSSION 



Throughout the range of the striped bass 

 the number of spines in the first dorsal fin is 

 remarkably constant except for the high values 

 for the James River samples . A study of the 

 constancy of this character in several year 

 classes through a considerable mileage of the 

 James and Hudson Rivers shows it to be quite 

 stable which would hardly be the case if it were 

 influenced to any considerable extent by environ- 

 mental fluctuations. This character alone in- 

 dicates the presence of two well-defined 



subpopulations in the Chesapeake Bay area . For 

 two year classes the James River, the most 

 southerly drainage in Chesapeake Bay, has the 

 high values which contrast with others but 

 particularly with the nearby York -Rappahannock - 

 Pocomoke systems. The latter three have in 

 turn somewhat lower values than samples from 

 the Upper Bay. The James sample is also much 

 higher than the next most southerly sample from 

 Albemarle Sound which confirms the returns 

 from tagging experiments that show little ex- 

 change between the two populations. The James 

 River subpopulation also differs in this regard 

 from others studied along the Atlantic and Gulf 

 coasts . It approaches but differs significantly 

 from the Hudson population. 



In contrast to the high value for first 

 dorsal spines, the James River sample has low 

 or moderate values for soft dorsal rays and 

 soft anal rays . Because of this relationship be- 

 tween the fin spines and the soft ray counts seen 

 above, a character or meristic index was deter- 

 mined for each specimen by subtracting for each 

 specimen the number of first dorsal fin spines 

 from the total number of soft dorsal and anal 

 rays. The results for the 1955 year class in 

 table 21 show the James sample to be markedly 

 different from the York -Rappahannock samples 

 and also to differ from the Upper Bay samples 

 which have intermediate values. Chi-square 

 gives a value of X = 128 . 14 when the James 

 sample is tested against the York -Rappahannock 

 composite sample; X 2 = 92 .52 when the James 

 is tested against the EIk -Wicomico composite; 

 and the latter when tested against the York- 

 Rappahannock gives a value X = 21.74. These 

 values are significant at the one percent level, 

 which indicates the samples very probably were 

 not drawn from the same population . The data 

 for the 1954 year class (table 22) also shows the 

 James sample to be different from the other 

 samples from the Bay. When it is tested against 

 the composite Choptank -York sample, X 2 = 114.88 

 which is highly significant at the one percent 

 level and indicates they very probably were not 

 drawn from the same population. 



It may be seen from the data given in 

 table 21 that a line drawn between 13 and 14 of 

 the character index permits a separation of 67 

 percent of the James sample (low value) from 

 95 percent of the York sample (high value) or an 



92 



