Heupel et al.: Demographic characteristics of exploited tropical lutjanids 
427 
Table 1 
Parameter estimates for the von Bertalanffy growth function parameters age at 50% (mean asymptotic fork length) and per- 
cent longevity at 50% L x for five lutjanid species from the Great Barrier Reef. K is the von Bertalanffy growth coefficient, and 
t 0 is the theoretical age at length zero. “U” indicates an unconstrained estimate, “C” indicates an estimate constrained by t 0 = 0. 
Region-specific growth curves for L. carponotatus were not constrained. 
Species 
L ^ (mm) 
K (/yr) 
t 0 { y r) 
Age (yr) 
at 50% 
% longevity 
at 50% 
S. nematophorus — U 
820 
0.12 
-2.83 
3 
8.33 
S. nematophorus — C 
732 
0.26 
0 
3 
8.33 
A. virescens — U 
683 
0.35 
-1.53 
0.5 
3.13 
A. virescens — C 
623 
0.85 
0 
1 
6.25 
L. gibbus — U 
544 
0.06 
-9.48 
2 
16.67 
L. gibbus — C 
352 
0.51 
0 
3 
25.0 
L. fulviflamma — U 
265 
0.61 
1.66 
1 
5.88 
L. fulviflamma — C 
267 
0.41 
0 
1 
5.88 
L. carponotatus — U 
295 
0.37 
-2.58 
0 
0 
L. carponotatus — C 
291 
0.66 
0 
1 
4.35 
L. carponotatus — Lizard Is 
293 
0.67 
-0.17 
— 
— 
L. carponotatus — Mackay 
292 
0.47 
-1.68 
— 
— 
L. carponotatus — Storm Cay 
302 
0.16 
-9.35 
- — 
— 
Estimates of mortality for five lutjanid species using catch 
used in mortality estimation are indicated. 
Table 2 
curve and Hoenig (1983) estimators. Maximum 
age and age range 
Species 
Maximum age (yr) 
Age range 
(yr) 
Catch curve Z 
(/yr) [SE] 
Hoenig Z 
(/yr) 
S. nematophorus 
36 
3-17 
0.20 [0.05] 
0.11 
A. virescens 
16 
2-9 
0.56 [0.07] 
0.26 
L. gibbus 
12 
8-12 
0.63 [0.08] 
0.35 
L. carponotatus 
23 
7-23 
0.30 [0.02] 
0.18 
L. fulviflamma 
17 
10-17 
0.14 [0.06] 
0.25 
depth and time fished by commercial and recreational 
fishing crews. A small number of fishing crews fish dur- 
ing the night in deeper water (> 50 m) where a greater 
proportion of larger lutjanids are caught (Marriott, 
personal commun.). 
Limited sample sizes prevented the statistical analy- 
ses of sex- and region-specific variation in life history 
characteristics except for L. carponotatus. As with pre- 
vious findings, L. carponotatus displayed sex-specific 
differences in these characteristics, with males reach- 
ing larger maximum sizes than females. Reasons for 
sex-specific size and age distributions may be due to a 
wide array of factors, including regional conditions and 
physiological costs of sperm and egg production. Kritzer 
(2004) also found male L. carponotatus to be larger 
than females and suggested that this is an Indo-Pacific 
trait within the lutjanids because it does not always 
occur in other geographic areas. Such sex-specific differ- 
ences in lutjanid populations also may vary by region, 
although the magnitude of any sex-dependent variation 
within a geographic area remains poorly understood. 
Hence, our parameter estimates for the remaining spe- 
cies from samples pooled over regions of the GBR may 
not be as informative as we would like, but they nev- 
ertheless provide a good starting point for comparison 
and applicability to other regions where data remain 
scarce or absent. 
Age and growth 
Five of the seven species examined grew to similar sizes, 
but three of these demonstrated different longevities 
and the two largest species showed a twofold range in 
longevity for roughly similar maximum sizes, again 
illustrating the lack of a relationship between length 
and age across tropical lutjanids. High maximum ages 
