Kupchik and Shaw: Effects of recruitment through a coastal boundary layer on growth of larval Brevoortia patronus 
211 
A 
SL (mm) 
B 
Figure 2 
Histograms of standard length (SL) data for all Gulf menhaden (Brevoortia 
patronus) larvae collected at Bayou Tartellan, Louisiana, from October 2006 
to April 2007 and from September 2007 to April 2008 and that were used in 
analyses of sagittal otoliths: (A) all larvae between 5 and 16 mm SL, mean: 
10.9 mm (SD 2.51), and (B) all larvae greater than 16 mm SL, mean: 19.4 
mm (SD 1.39). Both histograms were normally distributed (Shapiro-Wilk’s 
test: P>0.05). 
2008. January 2007 accounted for 40% of all larvae col¬ 
lected during the period from October 2006 to March 
2007, and 30.3% of the total number of Gulf menhaden 
larvae were collected over both years. November 2007 
collections had the second highest number of larvae, 
accounting for 26.3% of all Gulf menhaden larvae col¬ 
lected in year 2, and 6.4% of all larvae collected across 
both sampling years. 
Length, age, and spawning dates 
There were a total of 240 Gulf menhaden larvae that 
had sagittal otoliths removed for analysis. Thirty-two 
otoliths did not produce readable radii and were ex¬ 
cluded from analysis. The length frequency of all larval 
Gulf menhaden that were aged (n=208) did not follow 
a normal distribution (Shapiro-Wilk: P<0.0001). As a 
result, we split the overall distribution into 2 groups to 
achieve 2 normal distributions, one of larvae between 5 
and 16 mm SL (mean: 12.1 mm SL [standard deviation 
(SD) 3.71]) and the second consisting of larvae greater 
than 16 mm SL (mean: 19.4 mm SL [SD 1.39]; Fig. 2). 
The mean SL in year 1 was 14.7 mm (SD 4.61), and 
the mean SL for year 2 was 16.3 mm (SD 4.83), with a 
slightly larger range. Overall, the largest larvae were 
collected from January through March. In year 1 the 
largest larvae were collected in January 2007, in year 
2 the largest larvae were collected in March 2008. 
Combining both sample years, larval Gulf menhaden 
had a mean age of 32.3 das (SD 12.15), a median of 
31.5 das, and a range of 11-67 das. For year 1, October 
2006 to March 2007, the ages ranged from 15 to 67 das. 
and a maximum density between 18 and 24 das. Also 
in year 1, the oldest larvae were collected in the largest 
numbers between December 2006 and February 2007. 
In year 2, September 2007 to March 2008, the high¬ 
est densities were for larvae between 35 and 45 das, 
and the oldest larval Gulf menhaden were collected in 
March 2008. 
In both sampling years, approximately half of all 
spawning dates for larvae sampled in Bayou Tartellan 
occurred before mid-January, and the other half oc¬ 
curred later in the year. In year 1, the greatest num¬ 
ber of spawning dates occurred from 1 to 28 February 
2007, and a smaller secondary peak occurred in Octo¬ 
ber 2006 (Table 1). During year 2, the greatest number 
of spawning dates occurred between 16 January and 15 
February 2008, and a second smaller peak occurred in 
late October or early November 2007. 
Gulf menhaden growth rates 
The 2-cycle Laird-Gompertz growth model provided 
a model fit that accounted for a faster initial growth 
rate and for a slower growth rate after the ontogenetic 
change (Fig. 3). The shift in growth rate and feeding 
pattern was estimated in the model to occur after 31 
dah (^*=31.086), or 33 das. The model estimated that 
length at hatching was 3.34 mm SL, and an age-specific 
growth rate at hatching of 0.0014/day. During this lar¬ 
val stage, the maximum growth rate was 0.72 mm/day, 
and mean growth rate was 0.47 mm/day. After the start 
of the developmental shift, at the modeled SL of 17.88 
mm, the age-specific growth rate was 0.0006/day. The 
