352 
Fishery Bulletin 107(3) 
found the highest abundance of juveniles in the inner 
reaches of Punta Banda Estuary throughout most of 
the year. Based on an annual survey, Hammann and 
Ramirez-Gonzalez (1990) reported higher abundance 
of juveniles in the central section of the same system 
between January and April. However, their sampling 
was limited to the main channel and did not include the 
inner reaches. Valle et al. (1999) reported that juvenile 
densities decreased from the mouth to the inner reaches 
of Alamitos Bay in southern California. In a fall survey, 
Fodrie and Mendoza (2006) found higher abundance of 
juveniles in the central and outer reaches of the sys- 
tems in southern California most similar in size, shape, 
and depth to Punta Banda Estuary (Batiquitos, Agua 
Hedionda Lagoon, Buena Vista, and Mission Bay). The 
density of juveniles captured in Punta Banda estuary is 
toward the lower range of those reported by Fodrie and 
Mendoza (2006) for medium-size embayments (termed 
lagoons in their study, range 4-30 fish/1000m 2 after 
taking into account their gear efficiency corrections). 
Juveniles were caught throughout the range of instan- 
taneous temperatures measured in Punta Banda Estu- 
ary (15-24°C), although our GLM analysis indicated 
a weak but significant negative relationship between 
temperature and density. Likewise, other studies have 
also reported capturing juveniles at a broad range of 
temperatures (e.g., Allen 1988; Kramer 1990; Fodrie 
and Mendoza 2006). Madon (2002) conducted labora- 
tory studies on juveniles ranging from 118-172 mm SL 
and found them tolerant to a broad range of tempera- 
tures (14-28°C) and salinities (8-34%o). Within this 
size range, growth and osmoregulation were positive 
at various combinations of temperatures and salinities, 
except when both were low and outside the range of 
those measured in this study (14°C 
and 8 %o). Likewise, laboratory stud- 
ies on California halibut between 
40-50 mm TL acclimated to 15°, 
18°, 21°, and 24°C indicate preferred 
temperatures are similar to acclima- 
tion temperatures (Esquer-Mendez, 
2006). Further, juveniles acclimated 
to 15-24°C only avoid temperatures 
substantially above and below those 
of the acclimation interval (<10.8°C 
and >29.1°C). The broad tempera- 
ture interval over which juveniles 
were captured in this and other 
studies is thus consistent with the 
high temperature tolerance of rela- 
tively small juveniles. 
In a review of juvenile flatfish dis- 
tribution in relation to environmen- 
tal conditions, Gibson (1994) noted 
that salinity generally has a limited 
effect on growth of juvenile flatfish, 
and that its primary effect is on dis- 
tribution and movement patterns, al- 
though others have noted that high 
salinities may imply a bioenergetic 
cost to juveniles (Wuenschel et al., 
2005). Although the GLM analysis 
indicated a weak, non-significant 
relationship salinity and density, 
juveniles were captured in variable 
densities over a range of salinities 
(31.6-38.9%e). Further, we found 
higher densities of juvenile Califor- 
nia halibut in the inner reaches of 
Punta Banda Estuary, where salin- 
ity is usually highest. Hence, it does 
not appear that the higher salini- 
ties we measured during our study 
limited habitat availability. Given 
that salinity gradients in season- 
ally arid estuaries are much more 
limited than in “classical” systems, 
20 
15 
10 
o • 
Ji * o J> 
v J 
20 
15 
10 
B 
12 14 16 18 20 22 24 26 
Temperature (°C) 
30 32 34 36 38 
Salinity (ppm) 
40 
■55 20 
15 
10 
2 3 4 
Depth (m) 
20 
15 
10 
D 
Q • 
• *> » • 
• \ *• 
09 , M * 
/p • 
~ §. . c tg& -V 
2 4 6 8 10 12 
Dissolved oxygen (mg/L) 
Figure 5 
Scatterplots of standardized density of California halibut ( Paralichthys 
californicus) caught in the outer (n = 62), central (n = 65), and inner (n = 66) 
sections of Punta Banda Estuary in relation to (A) temperature, (B) salinity 
(in parts per million, ppm), (C) depth, and (D) dissolved oxygen (in mg/L) 
measurements taken during trawl sampling excursions between October 
2004 and October 2005. 
