Nelson: Abundance, growth, and mortality of young-of-the-year Lagodon rhomboides 
325 
Table 2 
Results of the Pearson product moment correlation tests for indices of recruit abundance from 1989 to 1994 versus mean sea- 
surface temperature during the months before and during initial recruitment from 1988 to 1993 and for indices of adult abun- 
dance from 1988 to 1993 for Tampa Bay and Charlotte Harbor, r is the Pearson product moment correlation coefficient, P is the 
significance probability, and n is the sample size. MRFSS = Marine Recreational Fisheries Statistical Survey. 
Tampa Bay Charlotte Harbor 
Month 
r 
P 
r 
P 
n 
YOY indices-temperature 
October 
-0.05 
0.92 
0.67 
0.15 
6 
November 
-0.78 
0.11 
0.84 
0.03 
6 
December 
0.15 
0.78 
-0.21 
0.67 
6 
YOY indices-MRFSS adult indices 
0.86 
0.02 
-0.15 
0.78 
6 
Tab!e 3 
Regression statistics for mean length (ML) versus month 
(m) for young-of-the-year pinfish captured at fixed seine 
stations. The regression takes the form: Ln (ML) = ln(L 0 ) + 
G x m where ln(L 0 ) is the intercept and G is the instanta- 
neous growth rate or slope. Only data from April to July 
were used. All slopes and intercepts were significantly dif- 
ferent from zero. 
Year 
ln(L 0 ) 
SE 
G-value 
SE 
r 2 
n 
Choctawhatchee Bay 
1993 2.03 
0.217 
0.26 
0.038 
0.956 
4 
1994 
2.61 
0.162 
0.18 
0.029 
0.954 
4 
Tampa Bay 
1989 
2.77 
0.078 
0.18 
0.014 
0.988 
4 
1990 
3.53 
0.116 
0.06 
0.021 
0.818 
4 
1991 
3.17 
0.030 
0.10 
0.005 
0.994 
4 
1992 
2.64 
0.072 
0.20 
0.013 
0.992 
4 
1993 
2.49 
0.274 
0.21 
0.049 
0.904 
4 
1994 
2.98 
0.175 
0.14 
0.031 
0.905 
4 
Charlotte Harbor 
1991 2.38 
0.095 
0.26 
0.017 
0.991 
4 
1992 
2.96 
0.123 
0.14 
0.022 
0.954 
4 
1993 
2.46 
0.243 
0.21 
0.043 
0.920 
4 
1994 
2.81 
0.266 
0.16 
0.047 
0.857 
4 
and therefore feed little at night [Kjelson and John- 
son, 1976]). 
Young-of-the-year pinfish that settle to deep wa- 
ter move to shallow-water areas in early spring. Evi- 
dence for this is the peak in trawl abundance ofYOY 
pinfish in all years, followed by a rapid decline be- 
fore the peaks in abundance at seine stations in 
Choctawhatchee Bay and Tampa Bay (Fig. 2). This 
movement to shallow water may be due to YOY seek- 
ing food and refuge from predators because it coin- 
cides with seasonal increases in seagrass biomass 
and prey abundance in shallow waters (Thoemke, 
Table 4 
Relative abundance (no. of fish/100 m 2 ) for April to June 
averaged over all years and estimates of total instanta- 
neous mortality (Z) for young-of-the-year pinfish ( Lagodon 
rhomboides) in Choctawhatchee Bay, Tampa Bay, and Char- 
lotte Harbor. Data used to estimate Z are boldface. 
Month 
Choctawhatchee 
Bay 
Tampa 
Bay 
Charlotte 
Harbor 
April 
163.6 
164.2 
97.2 
May 
228.2 
88.5 
48.9 
June 
119.2 
39.1 
18.7 
-Z 
0.022 
0.021 
0.023 
1979; Lewis et al., 1985) and because the shallow 
water and structural complexity of seagrasses may 
provide protection from predation (Savino and Stein, 
1982; Stoner, 1983; Ruiz et al., 1993). 
Young-of-the-year pinfish move from shallow-water 
to deepwater areas in mid- to late summer, and this 
movement appears to be related to YOY size. Evi- 
dence for this is the shift to larger sizes in trawls in 
July (Figs. 3-5) concurrent with increasing catches 
in trawls in Tampa Bay and Charlotte Harbor (Fig. 
2). This movement may represent the initiation of 
their fall spawning migration (Caldwell, 1957; Han- 
sen, 1970) because gonadal recrudescence begins as 
early as July (Cody and Bortone, 1992) and because 
the modal lengths observed in trawls in July were about 
80 mm, which is the minimum size observed for YOY 
pinfish with developing gonads (Hansen, 1970). 
Factors affecting YOY spatial abundance 
Without meaningful, significant first-order interac- 
tions in the GLM analyses, the YOY abundance and 
main effect (zones, deployment technique, and bot- 
