THE IMPACTS OF ESTUARINE DEGRADATION AND CHRONIC POLLUTION 
ON POPULATIONS OF ANADROMOUS STRIPED BASS (MORONE SAXATILIS) 
IN THE SAN FRANCISCO BAY-DELTA. CALIFORNIA: 
A SUMMARY 
Jeannette A. Whipple, R. Bruce MacFarlane 
Maxwell B. Eldridge, and Pete Benville, Jr. 
Tiburon Fisheries Laboratory 
NOAA/National Marine Fisheries Service 
Introduction 
When most of us think of pollution effects on the marine 
environment, we are likely to think of dramatic events such as 
major tanker accidents and oil spills, or fish kills resulting 
from sewage effluents and toxic spills. These incidents are 
highly visible and receive considerable public attention. There 
is no doubt that such occurrences are damaging to the marine 
environment and warrent concern about the protection of that 
environment. 
Unfortunately, we may be deluded into thinking that if we 
prevent or ameliorate damage from such catastrophic events, our 
pollution problems have been solved. If we do this, we overlook 
a potentially greater problem -- that is continual or chronic 
input of pollutants at lower levels. For example, in the 1960s, 
there was considerable activity leading to decreased sewage 
pollution of San Francisco Bay. This was certainly commendable, 
but also led to the impression that our pollution problems were 
over. Little attention was paid to the less visible and poten¬ 
tially more harmful effects of increasing pollution from "water- 
soluble" chemicals. 
The long-range effects of chronic exposure to pollutants on 
our aquatic resources are still relatively unknown. Levels of 
pollutants, in this situation, are lower but more prevalent. 
Effects, if they occur, are more subtle, yet the damage to our 
resources may be considerable and, in many cases, irreversible. 
It is difficult to study effects of chronic pollution for a 
number of reasons. First, most marine ecosystems potentially 
impacted by pollutants are inherently complex and variable in 
space and time. Many ecosystems are described incompletely, 
either qualitatively or quantitatively, and even under com¬ 
pletely natural conditions. Natural perturbations may exceed 
those induced by man's influence. For example, in 1983 the El 
Nino off the coast of California resulted in warm water 
conditions and significant alterations in distribution and 
survival of coastal fishes. This makes it very difficult to 
detect alterations in the environment ascribable to pollution, 
and even harder to predict them. 
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