Secondly, circulation patterns can affect the distribution 
of the larval stages of many fish. Larval English sole distri¬ 
butions appear to reflect outflow related circulation changes. 
English sole spawn offshore in the Pacific Ocean. Adult sole 
usually do not occur in San Francisco Bay. The larvae spawned 
offshore presumably are carried by gravitational circulation 
into the Bay. The magnitude of that circulation is related to 
the magnitude of Delta outflow. Data from 1980-1983 showed that 
the distribution of larval sole (3-5 mm) was broader during the 
high flow years than during the low flow year. During the year, 
larval sole occurred only near the mouth of the Bay, near the 
ocean, while during the high flows (1983) larvae were found 
throughout San Pablo and South Bays. 
Early study efforts also have found that large, freshwater 
pulses move through the system in winter and spring and signifi¬ 
cantly lower salinity in this system. These salinity changes 
affect fish distribution. As a rule, pelagic species (e.g., 
northern anchovy) normally found in the Delta, Suisun and San 
Pablo Bays during dry periods move downstream after these 
pulses. On the other hand, some bottom species (e.g., juvenile 
English sole) usually found in Central Bay move upstream during 
these events. 
It also has been found that flow altered distributions of 
certain species result in increased abundance of these species. 
For example, a major cause of the year-to-year variation in 
abundance of Crangon shrimp appears to be survival of the early 
life stages (i.e., the larvae or juvenile), not to the number of 
reproductive females present. It has further been found that 
distribution of the adults that is affected by the flows varies 
between the years. In wetter years, the reproductive population 
is further downstream near the Golden Gate. The survival of the 
juveniles is much higher there. It appears that flow affects 
distribution of adults, which in turn sets abundance for the 
year because more juveniles survive. 
Future Project Needs 
The above provides a quick, general summary of the 
accomplishments of the Interagency Program and the findings of 
the Delta Outflow Study, in particular. The remainder of this 
review will emphasize future project needs. 
In order to ensure protection of San Francisco Bay 
resources, various things are needed. More information on water 
quality or pollution impacts on fishery resources in the Bay is 
desperately needed. The Delta Outflow Study has documented flow 
related effects, but little is being done to determine effects 
of various waste discharges on fish and shrimp. Once again this 
points to a division of study effort. One effort to study 
pollution in the Bay by the Aquatic Habitat Institute is being 
planned, but without strong local or Federal financial support, 
this program will not be productive. 
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