partial egg resorption 
complete egg resorption in maturing ovary 
no ovarian maturation in sexually mature fish 
egg death 
- reduction in number of eggs (fecundity) 
Pollutants, therefore, can lead to additional decreases 
in the egg production of the population. Additional delayed 
mortality may have occurred in embryos and larvae after 
spawning, resulting in even further reduction in survival. 
o Multiple regression analyses were done with data 
collected for the years 1978 to 1984 (7 years) from 
San Joaquin and Sacramento Rivers. Results showed 
that survival to young-of-the-year related to age 
distribution of spawning adults, outflow and diver¬ 
sion, petrochemicals and egg resorption. The best 
correlation was with egg resorption (Figure 7). 
The hierarchy of relationships is probably as fol¬ 
lows (Figure 8): Environmental factors such as 
lower outflow are associated with higher petrochemi¬ 
cal contmination; higher residues of petrochemicals 
interact with inherent factors in prespawning 
adults to affect condition and reproduction. 
Greater egg resorption occurs and subsequently 
there is higher larval mortality. Higher mortality 
of eggs and larvae results in lower abundance of 
juvenile striped bass. The important result, in 
terms of fisheries management, is that recruitment 
to the fishery is reduced. If successful, this 
method can lead to the forecasting of recruitment 
several years in advance. Our results so far, 
however, are for a short period (7 years) and need 
to be validated by continued monitoring before 
conclusions can be drawn. 
Conclusions 
The San Francisco Bay-Delta estuary has been modified in 
several ways since humans settled this area (Nichols et. al. 
1986). Among the most significant of these is the elimination 
of habitat for fish and other biota through human activities 
such as filling of wetlands and diversion of water for agricul¬ 
ture. Further degradation of this estuary due to increased 
diversion of water and increased disposal of toxic wastes is 
predicted. 
101 
