Lopez-Rasgado and Herzka: Assessment of habitat quality for juvenile Paralichthys californicus 
349 
tions (~3 vs. 1.5 fish/1000 m 2 ). ANOVA results indi- 
cated that density varied significantly as a function 
of time (F 12 154 =3.97, P<0.005) and among sections 
of the estuary (F 2 154 = 4.77, P=0.009). The interaction 
between factors was not significant (F 2 4 154 = 1.33, P 
= 0.154). Post-hoc multiple comparison tests indicated 
that density was significantly higher in the inner 
estuary (4.55 ±1.02 fish/1000 m 2 ) than in the central 
section (2.46 ±0.88 fish/1000 m 2 ). In addition, density 
was significantly higher during winter (November 
and February) than during most summer months 
(June through October). 
The size distribution of juveniles varied as a func- 
tion of time and section of the estuary. Recent re- 
cruits (<70 mm SL; Kramer, 1991) were relatively 
abundant throughout the estuary between October 
2004 and February 2005, indicating that the peak 
in estuarine immigration occurred during winter. 
However, fish 60-80 mm SL were also captured be- 
tween May 2005 and July 2005. In the outer section, 
a large proportion (79% of total) of juveniles <100 
mm SL were caught between October 2004 and April 
2005; few individuals were >200 mm SL (Fig. 2B). 
Between May 2005 and October 2005, a greater per- 
centage of the fish caught were >200 mm SL (range 
21 to 52%, Fig. 20. In the central and inner sec- 
tions, 87% and 85% of all fish caught were <200 mm 
SL. Throughout the estuary, juveniles <200 mm SL 
predominated between October 2004 and April 2005 
(89% of total); fish >200 m SL were more frequent 
between June2005 and October 2005 (23% of total, 
Fig. 3). 
The size-frequency distributions for the outer and 
central sections exhibited a single marked peak of 
40-90 mm SL (51% of all fish caught) and 40-70 mm 
SL (32% of all fish caught), respectively (Fig. 4). In 
contrast, the size-frequency distribution of halibut 
caught in the inner section had a primary peak at 
40-70 mm SL (21% of all fish caught) and a broad, 
secondary peak at 100-150 mm SL (28 % of the total 
catch). However, the size-frequency distributions of 
California halibut did not differ significantly among 
the outer, central, and inner sections of the estuary 
(Kruskall-Wallis H=1.35, P=0.51). The maximum SL 
found in the outer, central and internal sections of 
Punta Banda Estuary was 680, 788, and 784 mm, 
respectively. 
Instantaneous measurements of temperature, sa- 
linity, DO, and depth taken during trawling varied 
throughout the year (range 15-24. 0°C, 32-38%c, 
3-11 mg/L; Fig. 5). The GLM results indicated that 
density was signicantly and negatively related to 
temperature (f3= 0.59, F= 5.50, P=0.020), sampling 
time (F=2.264, P=0.039), and the interaction be- 
tween temperature and salinity ( /3 = 0 . 0 1 6 , F=4.906, 
P= 0.0208). All other predictor variables were not sig- 
nificantly related to density, although there was a 
weak negative relationship with salinity (/?=- 0.302, 
F=3.274, P=0.072). The GLM explained a low propor- 
tion of the variance (multiple r 2 = 0.208). 
co 
E ST 
E E 
o o 
O o 
CM O 
VI J- 
o 
14 
12 
10 - 
8 - 
6 - 
4 - 
Outer 
Central 
Inner 
0 
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct 
28 i 
26 
24 - 
22 - 
20 
18 
16 - 
14 
12 
Oct 
Outer 
Central 
Inner 
Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct 
Figure 2 
(A) Density of juveniles <200 mm standard length (SL) 
and (B) late juveniles >200 mm SL and adults of Cali- 
fornia halibut (Paralichthys californicus) captured in the 
outer, central, and inner sections of Punta Banda Estuary 
between October 2004 and October 2005. Values represent 
means ± standard error (SE). (C) Continuous temperature 
measurements made at locations in the outer, central and 
innermost sections of Punta Banda Estuary. Missing data 
reflect loss of thermographs. 
Otolith growth rates of natural populations 
Two-way ANOVA of log-transformed recent otolith 
growth rates indicated a significant interaction 
between time and section of the estuary (F 10 249 = 8.30, 
P<0.001). In the outer section, the highest mean growth 
