The results of sampling in 19 1*9 for striped bass larvae are given 

 in Appendix Table 12. Sampling for larvae was carried on jointly with 

 that of egg collecting. The first striped bass larvae were taken in 

 plankton hauls during cycle 13 (April 18-21, 191*9) at stations l } 1 3 

 and 16. From then on the catches increased each week with a peak yield 

 in cycle 20 (June 6-9, 19h9) when larvae were taken at 11 of the 26 

 stations. A larger total catch was recovered in cycle 16 but was re- 

 presented almost entirely from stations 16 and 17. The recovery of 

 larval bass diminished in numbers as the season progressed, with the 

 last larvae taken in the 23rd. cycle (June 27-30, 19U9) at station 15. 



Significant numbers of striped bass larvae were taken at stations 

 located in Sacramento River from Isleton to Toland's Landing, in 

 Georgiana Slough, and in Mokelumne River below the mouth of Georg- 

 iana Slough. The catches of larvae in Sacramento River were first 

 made in the l8th towing cycle (May 23-26, 19U9). This was a month 

 later than the appearance of larvae in the San Joaquin Delta. The 

 larvae captured in Sacramento River represented the production from 

 spawning activity occuring in Sacramento River and tributaries north 

 of the city of Sacramento (Calhoun, 19U8) . 



Representative catches of striped bass larvae were recovered from 

 station 26, located off Chipps Island, from May 9 through June 23, 19u9. 

 These larvae were of both Sacramento and San Joaquin River origin. 

 Samples of striped bass larvae from the southern part of the Delta be- 

 tween Mossdale and the Tracy Pumping Plant were few in comparison to 

 the eggs taken. Two factors may account for the small number of 

 larvae recovered from this area: (1) the drift of the eggs and larvae 

 from the area with the net outflow of water and (2) possible high rate of 

 mortality. 



The seasonal catch of striped bass larvae expressed in terms of 

 a standard volume of water strained was derived for each station (see 

 Appendix Table lit) . A graphic composite illustrating the relative 

 abundance and dispersion of striped bass larvae from April 18 to July 

 1, 19h9 } is shown in Fig. 6. A comparison of this chart with that 

 of the egg chart shows the dispersion of the larvae in a pattern con- 

 siderably different from that of the eggs, with the exception of San 

 Joaquin River between the mouth of Old River and Antioch. 



The lack of larvae in the southern part of the Delta is demons- 

 trated very clearly and indicates that the net outflow of water in 

 19l*9 probably was one of the causes of the dispersion pattern ex- 

 hibited by the larvae. The positive action of Sacramento River flows 

 in flushing the larvae from the upriver spawning areas is obvious from 

 the number of larvae present in Sacramento River below Walnut Grove. 



26 



