the Sacramento-San Joaquin Delta is reflected indirectly by the plank- 

 ton net catches of eggs at the twenty- five stations. The first collec- 

 tion of eggs, a small one, was made in San Joaquin River near Antioch 

 on April 30th. Delta water temperatures ranged from 55 degrees to 65 

 degrees Fahrenheit at that time. Significant catches of bass eggs were 

 first made May 5th (cycle 3) in San Joaquin River near Mossdale and 

 below the bifurcation of San Joaquin River, and Middle River, stations 

 8, 11, and 12. Samples of eggs were taken from this area until May 28th 

 (cycle 6), establishing the fact that San Joaquin River above the Delta 

 is a breeding area of considerable importance. Spawning activity spread 

 into the central portion of the Delta during cycles It and 5, with a con- 

 siderable number of bass eggs taken in Middle River at station 10, and 

 in Old River at stations 3 and 5. Stations 15, 16 and 17 in the central 

 and western portions of the Delta were most productive in eggs yields 

 from the itth through the 8th towing cycle (May h to June 16). Spawn- 

 ing continued sporadically to the end of June. Evidence of striped bass 

 breeding in Sacramento River was observed June lUth and l5th when several 

 eggs were recovered in the river at Isleton and in Georgiana Slough. These 

 eggs were probably flushed downstream from spawning areas in Sacramento 

 River above the Delta (Calhoun, 19U8). No further recoveries of eggs were 

 made in Sacramento River, although stations were sampled regularly each 

 towing cycle. 



Plankton-net catches of larval specimens of striped bass were in- 

 significant throughout the season and were limited to cycles 8 and 9 

 (Table 8). No deep hauls were made with the plankton net in 19U8; 

 thus, our information on striped bass larva distribution is incomplete 

 for that year. 



The initial catches of striped bass in the post-larval stages of 

 development were made with the five-foot tow-net at eleven of the 

 twenty-five stations in the 10th towing cycle, July 2-12, 19ii8. The 

 appearance of young fry in the large net was abrupt, with signi- 

 ficant numbers taken at several stations in the western and central 

 portions of the Delta. Successive towing cycles yielded increasing 

 numbers of juvenile bass at additional stations. During the season a 

 total of 8,071 striped bass were captured with the large tow-net and 

 a random sample of 5,306 individuals were measured. Data collected 

 for each station are given in Appendix Table 9, and are further 

 summarized in Appendix Table 2. Distribution of young striped bass in 

 the Delta as determined from tow-net sampling is illustrated graphi- 

 cally in Figure 5. 



The largest concentrations of juvenile bass were at stations in 

 the western part of the Delta, which includes San Joaquin River from 

 the mouth of Old River to Antioch, and Sacramento River below Rio- 

 Vista. Juvenile bass were not taken in stations in Sacramento River 

 between Rio Vista and Walnut Grove. The peak of abundance and the 

 most extensive pattern of dispersion occurred in the 13th cycle, 



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