Lopez-Rasgado and Herzka: Assessment of habitat quality for juvenile Paralichthys californicus 
351 
and 25.7°C (Fig. 2B). There was a positive relation- 
ship between density and recent growth rates, but the 
relationship was not statistically significant (r=0.43, 
P= 0.074). 
Somatic and otolith growth rates of caged fishes 
Throughout the caging experiments, two cages were lost 
in the outer section after the first two weeks. Another 
12 cages were not recovered after 28 days (mostly from 
the outer section; Table 1). Excluding fish from cages 
that were not retrieved, 72.7% (131 juveniles) and 72.8% 
(83 juveniles) were recovered after 14 days and 28 days, 
respectively. 
Recent otolith growth rates during the first 14 days 
were 5-6 times lower than those of wild-caught Cali- 
fornia halibut (1-2 pm/d, Fig. 6B). Minimum otolith 
growth was also detected during the second half of each 
caging period (Fig. 60. Somatic growth rates measured 
after 14 and 28 days were very low, indicating that 
conditions within the cages did not favor growth (Fig. 
6, D and E). We therefore concluded that the growth 
rates of caged individuals did not reflect habitat value 
and did not test for growth differences between sections 
or caging periods. 
Despite the low growth rates, there was a significant 
positive correlation between somatic and recent otolith 
growth of caged fishes during the first 14 d of the ex- 
periments (/•=(). 76, F 1 12y = 176.07, P<0.001, Fig. 7). This 
finding indicates that otolith and somatic growth are 
coupled in California halibut juveniles, even at very 
low growth rates. There was also a significant negative 
correlation between somatic growth rates and mean 
temperature (r= 0.56, F in =5.15, P =0.044), although 
the correlation between otolith growth rates and tem- 
perature was not significant (F 1 u =1.21, P= 0.295; data 
not shown). 
Gut fullness levels 
Most juveniles captured in the wild had at least some 
food in their digestive tract (62%, 60%, and 64% of 
total in the outer, central and inner sections of estuary, 
respectively; Fig. 8A). The percentage of individuals 
with gut fullness levels >50% ranged roughly between 
40 and 80%, varying as a function of time and section 
of the estuary. In general, fewer fish exhibited empty 
guts during the early spring and summer. In contrast, 
most of the fishes recovered from the cages after 14 days 
exhibited empty stomachs (Fig. 8B). Only occasionally 
did some caged individuals have noticeable amounts of 
food in the digestive tract. 
Discussion 
Density and environmental variables 
California halibut <200 mm SL were consistently cap- 
tured throughout Punta Banda Estuary, indicating the 
SL (mm) 
Figure 4 
Size-frequency distributions of California 
halibut (Paralichthys californicus) captured 
in the outer, central, and inner sections of 
Punta Banda Estuary between October 2004 
and October 2005. Individuals smaller than 
70 mm standard length (SL) are considered 
recent recruits. The 250 mm SL size class 
includes fish >250 mm SL. 
entire system is used as juvenile habitat. Based on the 
relationship between daily otolith increment counts 
and SL reported by Rosales-Casian (2004) for juveniles 
caught in northern Baja California, and the age-length 
relationship reported by Hammann and Ramirez- 
Gonzales (1990) for halibut captured in Todos Santos 
Bay (TL (cm) = 8.98+9.51Age (yr)) fish <180 mm SL are 
young-of-the-year (see also Haaker, 1975; Kramer, 1991). 
Maturity occurs at approximately 20-23 cm total length 
(TL) for males and 38-47 cm TL for females (Haaker 
1975; Love and Brooks 1990). Hence, most of our catch 
was comprised of juveniles, although some adults were 
also caught. 
The distribution of juveniles relative to the mouth of 
medium-sized estuaries in Baja California and south- 
ern California appears to vary among systems. We 
