Call Ihan et al: Effect of demography on the spatial distribution of the Albemarle Sound-Roanoke River stock of Morone saxatilis 
133 
Females Males 
50 
40 
30 
20 
10 
0 
Total length (mm) 
Figure 1 
Size distributions of tagged Striped Bass ( Morone saxatilis) by time period and 
sex. Fish were collected by electrofishing during spring in the Roanoke River. Note 
that sex was determined for nearly all (>99%) tagged fish. Data from 1994 were 
excluded because few fish (n= 9) were tagged that year. 
1991-93 
(/?= 1331) 
50 1 
40 
30 
20 
10 
il 
1991-93 
(n=4981) 
to the NCDMF, whose contact information was printed 
on the tag. 
Data analysis 
We used multinomial logistic regression to evaluate 
the effects of fish size and stock abundance on the 
recapture location (i.e., to evaluate the movements) 
of Striped Bass of the AR stock. For this analysis, 
recapture locations of tagged fish were assigned to 1 
of 4 broad geographic areas: 1) the Albemarle Sound 
estuary, 2) the Pamlico Sound estuary, 3) ocean wa- 
ters of North Carolina, or 4) northern coastal waters 
from Virginia to Massachusetts (Fig. 2B). Therefore, 
recapture area constituted a multicategory response 
variable. Explanatory variables were fish size (TL at 
tagging) and total annual abundance of the AR stock 
(1991-2008). Annual abundance estimates (of age 1+ 
fish) were obtained from a statistical catch-at-age 
model from the most recent AR stock assessment 
(NCDMF and NCWRC 2 ) and served as a proxy for the 
annual densities of conspecifics (AR stock only) with 
which tagged Striped Bass were expected to interact 
each year. Sex was not included as an explanatory 
variable because it was confounded with fish size be- 
yond 800 mm TL because all but 4 tag returns from 
this size range were from females. However, across 
smaller sizes (400—800 mm TL), over which sexes were 
more equally represented, similar-size males and fe- 
males were generally recaptured in the same areas, 
indicating that movements differed little between 
sexes. 
For the purpose of our analyses, we included only 
tag returns that occurred after the first 2 weeks but 
within the first calendar year at liberty. By restrict- 
ing returns to those returns that occurred within the 
first calendar year at liberty (on or before 31 Decem- 
ber), movement between tagging and recapture loca- 
