Rulifson and Batsavage: Population demographics of A/osa mediocns 
227 
Table 1 
Percent agreement of ages, measured in years, from scales and otoliths of Hickory Shad ( Alosa 
mediocris ) collected in Albemarle Sound from February to May 1996. Data represent percent 
agreement calculated with otolith age as the standard; bold numbers indicate one-to-one cor- 
respondence (100% accuracy). 
Scale 
age 
Total number of 
Otolith age 
2 
3 
4 
5 
6 
7 
otoliths examined 
2 
0 
65 
35 
0 
0 
0 
20 
3 
4 
62 
30 
4 
0 
0 
242 
4 
0 
23 
61 
15 
1 
0 
192 
5 
0 
15 
55 
25 
5 
0 
20 
6 
0 
0 
0 
0 
50 
50 
2 
7 
0 
0 
0 
0 
50 
50 
2 
Total number of 
scales examined 
10 
209 
208 
44 
5 
2 
478 
Because of the deciduous nature of Alosa scales, oto- 
liths were used for age composition analyses, mortal- 
ity estimates, and back calculations of length at age. 
Scales that agreed in age with their respective otoliths 
were used for spawning mark analysis. 
The Hickory Shad population in the Albemarle 
Sound and Roanoke River ranged from age 2 to age 7, 
but the majority were age-3 and age-4 fish (Table 2). 
Age-3 males were dominant (66%), and the majority of 
females (55%) were age 4. Females were larger at age 
than were males, but size ranges (Table 2) and weights 
(Table 3) at age for each sex showed some degree of 
overlap. 
There was a strong relationship between otolith ra- 
dius and FL. The following equations were used to ex- 
press this relationship: 
Males: FL = 133.32 (otolith radius) - 62.35, 
(r 2 [coefficient of determination] =0.95); (8) 
Females: FL = 116.54 (otolith radius) 
- 31.18, (r 2 =0.92); and (9) 
Sexes combined: FL = 117 ,02(otolith radius) 
- 29.20, (r 2 =0. 93). (10) 
The von Bertalanffy growth equation was 
L t = 460 (1 - e-°- 24( ' + 163) ). (11) 
In general, the mean back calculations of length at 
age were shorter than the observed lengths for younger 
fish and longer than observed lengths for older fish (Ta- 
ble 2). With the proportional method, back-calculated 
lengths for male Hickory Shad of ages 2-4 were shorter 
Table 2 
Observed means and ranges of fork lengths at age, measured in millimeters and years, respectively, and back-calculated 
estimates of fork lengths at age of male and female Hickory Shad ( Alosa mediocris) collected from the Albemarle Sound-Roa- 
noke River watershed in 1996. Sexes combined represent the predicted size-at-age from the von Bertalanffy growth function 
(VBGR). Standard deviations (SD) are provided in parentheses. n= number of fish sampled. 
Age 
Males 
Females 
Sexes 
combined 
(VBGR) 
n 
Mean (SD) 
Range 1 
Calculated 
n 
Mean (SD) 
Range 
Calculated 
1 
0 
206 
0 
212 
215 
2 
16 
293 (9.3) 
278-314 
247 
9 
304 (7.0) 
292-313 
263 
268 
3 
178 
288 (12.9) 
257-328 
287 
78 
313 (18.4) 
280-360 
306 
309 
4 
69 
319 (11.9) 
283-354 
293 
133 
339 (15.3) 
296-390 
345 
341 
5 
4 
332 (16.4) 
318-355 
355 
18 
343 (18.8) 
320-397 
363 
366 
6 
1 
376 
1 
402 
402 
386 
7 
0 
2 
397 (4.2) 
394-400 
394 
402 
Total 
268 
241 
