The most striking inconsistency in figure 6 is the lack oi' correlation 

 for 1939 between growth on the one hand and diatom persistence and surface 

 salinity on the other; also between surface temperature and surface salinity. 

 Although the surface watjr at La Jolla was abnormally warm in 1939, it vras 

 also of abnormally high salinity; and though the diatom count vras high, the 

 average growth of fish of the year was below nornKil. 



The breakdovm of correlation between temperature and salinity suggests 

 an important anomaly in the current pattern in 1939 in the vicinity of La Jolla. 

 The relatively i/eak northvtrest -winds prevalent that year are consistent v/ith 

 relatively weak upwclling; and the increase in salinity and temperature can 

 indicate an increase in the admixture of "southern water" (cf . Sverdrup, 

 1938). The biological evidence of a change in hj^'drograp hie conditions is 

 equally suggestive. Certain species of diatoms normally occurring several 

 weeks of the year at La Jolla were absent in Dr. Allen's samples of 1939, 

 notably, Chaetoceros curvisetus, Chaetoseros laciniosus, Licmophora lyngbyei , 

 and Lithodesmium undulaturi t Among species occurring more frequently in 1939 

 than normally, those most noteworthy v/erc Rhizosolenia alata , Rhizosolenia 

 fragilissima and Rhizosolenia irabricata . The ecology of these species is 

 too little known to permit of interpreting their occurrence in terms of physi- 

 cal oceanography. It may be of significance, however, that among species 

 of the first group mentioned above, all have been listed by Cupp and Allen 

 (1938) as being south temperate neritic . forms , except Licmophora lyngbyei , 

 which is "tychopelagic". Among those listed Ik the second group ," Trhizosolenia 

 alata is an oceanic temperate form? and the other two are north temperate 

 forms . 



More direct evidence that a change in the environment of the pilchards 

 took place in 1939 is -the fact that an abnormally high production of yoiaig 

 pilchards occurred that year in v^raters far to the north of southern California, 

 v^hich is regarded as the usual chief spavming ground. This may have been 

 the result of abnormally high survival of young hatching from the number -of 

 eggs normally spavmad north of California. It may also have been the result 

 of abnormally heavy egg production in northern \/aters, permitted by a north- 

 ward extension of oceanographic conditions favoring spavming. In support of 

 the latter hypothesis is the fact that adult pilchards taken by fishermen in 

 mid-summer off Oregon and Vfashington were full of spawn, in contrast to their 

 usual immature condition at that time. That spavming actually occurred north 

 of California is proved by the fact that the Fish and vaidlife Service that 

 year collected pilchard eggs and larvae in tow nets off the Oregon coast 

 (Walfbrd and Moshcr, 19i|l). 



ViThatevur may account for it, an extraordinary rtumber of young pilchards 

 of year class 1939 were subsequently observed and caught from Oregon to 

 Alaska, as well as along the California coast. It has been previously ob- 

 served that the first year's grovfth decreases nortbvard (Walford and Mosher 

 I9U3). Thus the northv^ard extension of the range of year class 1939 could 

 alone account for its abnormally low first yearns growth in spite of the 

 apparently favorable food supply in southern California. 



115 



