170 
Fishery Bulletin 95 ( 1 ), 1997 
Table 4 
A summary of daily growth rate estimates from field studies. 
Location 
Size at age 1-yr 
(mm TL) 
Daily growth rate 
(mm/day) 
Data 
source 
Willapa Bay, Grays Harbor, 
and adjacent neashore, WA 
<150 
0.33-0.49 (May-Sep) 
This study, 1985-88 
Yaquina Bay, OR 
130-160 
0.49 (May-Oct) 
Westrheim, 1955 
Monterey Bay, CA 
130-150 
0.55 (May-Oct) 
Smith and Nitsos, 1969 
Yaquina Bay, OR 
100-140 
0.33 
Rosenberg, 1982 i2 
Moolach Beach, OR 
100 
0.34 
Yaquina Bay, OR 
<150 
0.46-0.49 (Mar-Oct) 
Krygier and Pearcy, 1986 2 
Moolach Beach, OR 
<150 
0.26-0.32 (Dec-Apr) 
0.28-0.42 (Apr-Oct) 
1 The original daily growth rates were estimated from fortnightly ring counts. 
2 Length at age 1 and daily growth rates were converted from standard length (SL) to total length (TL) by using the relationship: SL = -0.205 + 
0.848 TL (senior author, unpubl. data). 
Several previous studies with the LMP technique 
have attempted to estimate growth rates for English 
sole juveniles from estuaries and open coast but failed 
to consider the effect of interarea migration on the 
growth estimates. As a consequence, their results 
often show significant differences between coastal 
and estuarine populations (Westrheim, 1955; Smith 
and Nitsos, 1969; Krygier and Pearcy, 1986). In con- 
trast, growth estimated from fortnightly ring counts 
showed no differences between coastal and estuarine 
populations (Rosenberg, 1982). 
Previous laboratory studies where ration was held 
constant (Williams and Caldwell, 1978) showed that 
ambient temperature had no statistically significant 
effect on English sole growth rate between 9.5 and 
15. CPC but significantly reduced growth between 15.0 
and 18.0°C. The artificial food pellets used in that 
study may have been nutritionally inadequate, how- 
ever, making it difficult to extrapolate the results to 
field conditions. Laboratory studies by Yoklavich 
(1981), where live polychaetes were used as food, 
showed a significant decline in the mean growth rate 
of0 + English sole (from 1.87% to 1.17% of body weight 
per day) between 13.0 and 17.5°C. Our results do 
not indicate any statistically significant interannual 
effect of temperature on the growth of English sole 
juveniles over the range of population-weighted mean 
temperatures (10.5-16.2°C) observed under field con- 
ditions. Higher temperatures presumably result in in- 
creased benthic productivity (Johnson and Brinkhurst, 
1971) and in more food available to juveniles. On the 
other hand, metabolic requirements increase at high 
temperatures. Whether the juveniles grow faster or 
slower under field conditions probably depends on the 
bioenergetic balance at higher temperatures. 
Peterman and Bradford ( 1987) found that density 
had a significantly negative effect on the growth of 
1 + English sole off the Oregon and Washington coasts 
(P=0.024, one-tailed C-test); therefore it would be rea- 
sonable to expect that growth of 0 + English sole is 
also density dependent. Nevertheless growth rate 
and mean population size varied over relatively nar- 
row ranges in this study, and we were unable to de- 
tect any statistically significant density effect. 
The spawning season for English sole can extend 
from September to April (Kruse and Tyler, 1983), and 
recruitment processes are also protracted. Multiple 
peak recruitments are common (Kendall, 1966; 
Boehlert and Mundy, 1987; Gunderson et al., 1990; 
Shi et al., 1995), and peak recruitment occurs at dif- 
ferent times each year, depending on ocean tempera- 
ture and transport mechanisms (Ketchen, 1956; 
Boehlert and Mundy, 1987). Kendall (1966) reported 
that for Puget Sound English sole juveniles that were 
recruited earlier, growth was slower than that of later 
recruits during the same period. Our results led to 
the same conclusion, that is, timing of settlement 
influences the growth trajectory (Fig. 4). 
Different size groups of English sole have differ- 
ent prey requirements and suffer from different de- 
grees of food limitation (Gunderson et al., 1990). Off 
the Oregon coast, English sole 17-35 mm standard 
length (SL) fed primarily on polychaete palps, juve- 
nile bivalves, and harpacticoid copepods, whereas 35- 
82 mm fish fed on larger prey such as amphipods 
and cumaceans (Hogue and Carey, 1982). In the 
Humboldt Bay estuary, English sole smaller than 50 
mm TL fed almost exclusively on harpacticoid cope- 
pods whereas the diet of 66-102 mm fish was domi- 
nated by polychaetes (Toole, 1980). 
