Juvenile bass were sampled for fourteen consecutive weekly cycles, 

 terminating with the 33rd cycle, September 20-22, 19h9* A total of 

 20,2ii2 juvenile striped bass were collected with a five-foot tow net 

 and a random sample of 9,6l9 individuals was measured to observe the 

 seasonal rate of growth. The data collected from the twenty-six stations 

 are presented in Appendix Table 13, and are further summarized in Appen- 

 dix Table 2. The weekly distribution of the young bass and their rela- 

 tive density as determined from tow-net hauls is illustrated graphically 

 in Fig. 7. 



Initial catches of post-larval striped bass were made in the 20th 

 cycle (June 6-9, 19l;9) at several stations in the western part of the 

 Delta. The average size of the young fry taken in this cycle was 13.1 mm 

 (0.5 inch). An increasing number of stations yielded juvenile bass in 

 the succeeding cycles. During cycles 20-2U (June 6-30, 19^9) the prin- 

 cipal catches were made in the lower Delta, particularly station 17, 2$, 

 and 26. The number of young bass captured in the central Delta area and 

 San Joaquin River above Antioch began to increase in the succeeding 

 cycles. Many of the stations produced 300 to 700 individuals in a 

 standard tow, indicating the enormous population of juvenile striped 

 bass present in the Delta during July. The peak period of abundance 

 occurred during the 26th cycle (July 19-22, 19U9). The length of indi- 

 viduals measured during this cycle averaged 37.7 mm (l.U inch). Follow- 

 ing the cycle of peak abundance, there was a rapid decline in the number 

 of juveniles collected, particularly in the central and southern Delta. 

 Coupled with diminishing returns in the central section of the Delta, 

 was the apparent increase in catch in San Joaquin River at Antioch, and 

 Sacramento River off Chipps Island. This increase in the lower river 

 sections indicates a downstream movement toward the lower bay area. 

 By the end of the season, tow-net samples of juvenile bass were limited 

 to the lower Delta channels, with an occasional individual recovered in 

 the southern and central Delta. 



With the results available from two consecutive years of sampling 

 striped bass eggs, larvae, and juveniles at the established stations in 

 the Sacramento-San Joaquin Delta, certain facts concerning spawning, 

 distribution, and movements become apparent. 



The relative importance of the areas within the Sacramento-San 

 Joaquin Delta as striped bass spawning waters was determined during 

 19it8 and 19U9. Although in 19U8, frequency in sampling did not ap- 

 proach that of 19h9, the egg distribution was essentially the same. 

 The time and extent of the spawning seasons varied and was dependent 

 upon favorable water temperatures. Water temperatures of 60 degrees, 

 Fahrenheit and higher were normally encountered where eggs were taken. 

 The spawning season in 19U3 extended from the first of May to the end 

 of June, and In 19^9 the spawning began the first of April and ended 

 about the middle of June. 



27 



