Collins and McBride: Spatially explicit life-history dynamics of a protogynous reef fish 
235 
where = asymptotic fork length 
K = the Brody growth coefficient; and 
t 0 = the predicted age at which fish length is 
equal to zero. 
Growth was modeled for the entire sample, as well 
as independently by depth category (nearshore vs. 
offshore). 
To test for effects of fish age and depth on fish size, a 
2-way analysis of variance (ANOVA) was used to com- 
pare size at age for age classes common to both depth 
categories (ages 3-6 yr). Size and age at female matu- 
rity and sex change were calculated with the logistic 
curve (binary logit model): 
PM t = e a + bX /l + e a + b A 
where PM t is the probability of maturity at a particular 
age or length class; 
a and b = constants; and 
X is either length or age. 
Size or age at 50% maturity = |a/b|. Model structure 
and fitting followed Allison (1999). Size and age at first 
maturity (i.e., class 1 vs. classes 2-4) and at sex change 
(i.e, classes 1-4 vs. classes 5-10) were modeled for each 
depth category, as well as for the aggregate sample. 
Additional otoliths and gonads were collected oppor- 
tunistically through spearfishing tournaments, trawl 
research cruises (Fisheries-Independent Monitoring 
Program of the Fish and Wildlife Research Institute), 
and independent diver donations. Fish were used for 
life history analyses only if the location and depth at 
capture within the central eastern Gulf of Mexico could 
be verified. 
Results 
Research dives 
Hogfish presence was significantly related to habitat 
and depth. Fish were recorded most often and in high- 
est densities nearshore over rugose hard bottom (Fig. 
2A). Hogfish were present during 74% of all surveys 
(318/431) and were observed during all months of the 
year throughout the sampled depths and major habitat 
types (Tables 1 and 2). Hogfish density was greater near- 
shore (range 0-25; mean=5.4) than offshore (range 0-15; 
mean=1.3) during all seasons, and highest densities 
were recorded during summer (Fig. 2B). No significant 
relationship between presence and season was detected, 
nor was there a significant interaction between habitat 
and depth or season and depth (Table 2). 
Hogfish observed during research dives nearshore 
were half the size of those offshore (nearshore mean=24 
cm FL [range: 6—56 cm, n = 1352]; offshore mean=51 
cm FL [range: 18-77 cm, n=296]). Nearshore hogfish 
were larger in summer than in winter (P= 0.0029), 
and offshore hogfish were larger in spring than in fall 
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Figure 2 
Geometric mean density of hogfish (Lachnolaimus 
maximus) recorded during visual transects (50x6 m 
bands with replication) by (A) habitat type and ( B) 
season. (C) Mean fork length for hogfish observed 
over all seasons during all research dives. Depth cat- 
egories were classified as nearshore (<30 m depth; 
open circles) or offshore ( >30 m depth; filled circles), 
and error bars represent 95% confidence limits. 
(P=0.0141), but otherwise, no significant relationship 
was detected between fish size and season (Fig. 2C). 
Although density decreased with depth (PcO.OOOl; 
Fig. 3A), FL exhibited a positive relationship with 
depth (PcO.OOOl; Fig. 3B). Males were larger than fe- 
males within each depth category (P<0.0001), but both 
sexes were larger offshore than nearshore (PcO.OOOl; 
Fig. 3B). Within depth categories, further analysis by 
