Jones et al.: Population dynamics of Pogonias cromis 
455 
Year of birth 
Figure 5 
Year class distribution of black drum in the Chesapeake 
Bay fishery, 1990-92; juveniles excluded. 
100 - 
50 - 
0 -h 
I I Male 
75 100 125 
Total length (cm) 
150 
Figure 6 
Distribution of total lengths of black drum in the Chesa- 
peake Bay fishery, 1990-92. 
caught, apart from young-of-the-year, was age 6, and 
age at the 5 th percentile was 16 years. No fish be- 
tween 1 and 5 years were found. Recruitment to the 
gear appears to be complete by age 20 or 21. 
Black drum recruitment in Chesapeake Bay is 
characterized by occasional, dominant year classes 
(Fig. 5). Exceptionally large year classes occurred in 
1934 and 1942, demonstrated in an abundance that 
fell above the 95% confidence band of expected year 
class strength around the catch curve. Abundant, but 
not exceptional, year classes occurred in 1933, 1943, 
and 1968. Poor year classes, those that fell below the 
lower 95% confidence interval, occurred in 1939, 
1946, 1951, and 1958. We lack information on re- 
cruitment after 1972 because black drum are not fully 
recruited to the bay fishery until age 21. 
Total length of adult black drum in Chesapeake 
Bay averaged 109.5 cm, ranging from 78.7 to 130.2 
cm (Fig. 6). Median length (cm) in the catch was not 
significantly different from year to year (1990=109.2, 
1991=108.0, 1992=110.5; Kruskal-Wallis % 2 =4.52, 
P>0.05), although females were slightly longer than 
males ( S =109.2, $ =109.5, Wilcoxonz=2.06, P< 0.05). 
Length at the 95 th percentile was 121.9 cm, indicat- 
ing that many large fish were landed. 
Mean total weight of adult black drum in Chesa- 
peake Bay differed slightly between sexes and among 
years. Total weight of adults averaged 22.1 kg over 
the period 1990-92 and ranged from 11.3 to 49.4 kg 
(Fig. 7). Females were slightly heavier (ANOVA, 
F=8.23, P<0.05), probably due to their reproductive 
product. The difference between sexes, 1.1 kg, 
amounts to only 5% of average total weight. Fish in 
