Johnson et at: Fecundity and egg weight in Pleuronectes vetulus 
243 
Table 7 
Associations between nutritional and reproductive factors and biomarkers of contaminant exposure in English sole as deter- 
mined through multiple regression, while adjusting for effects of sampling time. P-value for regression factor, P-value, and sample 
number are shown. The sign of the t-value indicates the direction of the association (positive or negative). Statistically significant 
associations are indicated in bold. 
Nutritional and reproductive factors 
Exposure 
biomarkers 
Condition 
HSI 
Glucose 
Triglycerides 
Estradiol 
Vitellogenin 
GSI 
1.701 
6.297 
-1.902 
-1.880 
-0.739 
0.493 
-0.237 
Biliary 
P=0.0942 
P<0.0001 
P=0.0654 
P=0.0699 
P=0.4628 
P=0.6248 
P=0.8133 
FAC-BaP 
(n=6 2) 
(n=62) 
(n= 37) 
(77=33) 
(77=59) 
( 72=37 ) 
(77=62) 
1.287 
6.660 
-1.692 
-0.851 
-0.636 
-0.280 
-0.262 
Biliary 
P=0.2032 
P<0.0001 
P=0.0994 
P=0.4041 
P=0.5274 
P=0.7809 
P=0.7939 
FAC-NPH 
(t? = 62) 
(71=62) 
(n= 37) 
(72=33) 
(77=59) 
( 77 =37 ) 
(77=62) 
0.143 
3.905 
2.357 
3.786 
-1.209 
-2.717 
0.096 
Liver 
P=0.8870 
P=0.0002 
P=0.0228 
P=0.0005 
P=0.2305 
P=0.0093 
P=0.9328 
PCB’s 
o 
GO 
II 
(77=80) 
(77=47) 
(77=43) 
(77 = 77) 
(77=47) 
3 
II 
00 
o 
0.132 
5.279 
1.997 
1.920 
0.066 
-2.603 
0.676 
Ovary 
P= 0.8956 
P=0.0001 
P=0.0534 
P=0.0630 
P=0.9476 
P=0.0133 
0.5010 
PCB’s 
(n= 72) 
(77=72) 
(77=38) 
(77=34) 
(77=69) 
(77=38) 
(77=72) 
and maturity from other sites. Although this intersite 
difference in egg production pattern could represent 
a genetic adaptation of the Duwamish sole stock to 
its particular habitat, this is not likely on the basis 
of current knowledge of the population structure of 
English sole in Puget Sound. Sole populations resid- 
ing at our sampling sites do not appear to constitute 
discrete breeding populations but migrate to com- 
mon breeding areas, such as University Point or 
Duwamish Head in central Puget Sound, for spawn- 
ing (Collier et al., 1992). Moreover, their eggs and 
larvae are pelagic and therefore are transported from 
the breeding area to nearshore nursery ground set- 
tling sites in accordance with current patterns 
(Lassuy, 1989). Site-specific genetic adaptation would 
be unlikely in animals with such a breeding system, 
although some genetic divergence between subpopu- 
lations in northern and southern Puget Sound with 
distinct spawning areas is a possibility. Overall, 
marine fish show relatively little geographic diver- 
sity (Gyllensten, 1985), and their genetic structure 
is thought to be determined largely by the dispersal 
potential of the pelagic stages, rather than by adap- 
tation to local environmental conditions (Waples, 
1987). Studies of marine flatfish, such as the com- 
mon sole ( Solea vulgaris), turbot ( Scopthalmus maxi- 
mus), and flounder ( Platichthys flesus) in the north- 
eastern Atlantic and Mediterranean (Galleguillos and 
Ward, 1982; Blanquer et al., 1992; Kotoulas et al., 
1995), indicate that these species exhibit some geo- 
graphic isolation or differentiation due to tempera- 
ture gradients that inhibit larval transport and sur- 
vival but that they show fairly substantial gene flow 
on a regional level. In the common sole, for example, 
a species with a life history strategy similar to that 
of English sole, the geographic unit of population 
structure appears to lie within a radius of approxi- 
mately 100 km (Kotoulas et al., 1995). 
Changes in egg weight and number could also be 
associated with alterations in habitat characteristics, 
such as water temperature, food supply, and food qual- 
ity, all of which have been shown to influence egg de- 
velopment in English sole or other fish species. Win- 
ters et al. ( 1993), for example, demonstrated that win- 
ter temperature 2 to 3 months before spawning can 
affect fecundity and egg size in herring from the north- 
west Atlantic. Temperature can also affect the rate of 
gonadal development in English sole, and consequently 
egg size at a particular sampling time ( Kruse and Tyler, 
1983). In general, however, bottom temperature in 
Puget Sound is not highly variable over the geographic 
range encompassed by this study (Collias et al., 1974; 
Malins et al., 1980, 1982), and water temperatures in 
the Duwamish Waterway are comparable to those from 
sites in the main basin (Collier, 1988). Consequently, it 
is unlikely that temperature is a major contributing 
factor to the intersite differences in patterns of egg de- 
velopment that we observed in this study. 
The present findings suggest, on the other hand, 
that contaminant exposure and nutritional variables, 
