Paper 6 



80th percentile occurred in September and October at Cape 

 Mendocino. The indices for November and December showed a 

 gradual return to median values; however^ upwelling was still 

 indicated for 39N. As Bakun (1978) has already noted/^ such a 

 prolonged period of upwelling would appear to be favorable for 

 those fish stocks dependent upon upwelling based primary 

 produc ti on . 



POINT CONCEPTION TO BAJA CALIFORNIA 



A secondary California Current upwelling regime along this coast 

 (33N/ 119W to 21N/ 107W) is characterized by positive values of 

 offshore transport throughout the year (Bakun and Nelson in 

 press). Maximum upwelling index values occur from March to May 

 and coincide^ in time^ with major peaks in spawnino. 



Although the upwelling index remained positive during 1976^ the 

 most prominent features were the extended periods of large 

 negative anomalies in January and February/^ and again from August 

 to December. This pattern marked an almost complete reversal of 

 the conditions which prevailed in 1975. During the previous 

 yearr below median values occurred in summer* while above median 

 indices were evident in spring and fall. 



Positive monthly mean anomalies were evident from March to August 

 (Table 6.2). Much more intense than normal upwelling at 

 Locations from Punta Eugenia (E7N) to Cabo San Lucas (21N) 

 extended the upwelling season to late summer. This period was 

 immediately followed by a decline to large negative anomalies. 

 This pattern of negative anomalies during fall and early winter 

 encompassed the entire region from Point Conception (36N) to Cabo 

 San Lazaro (24N). Upwelling indices were consistently below the 

 30th percentiie/^ which suggested extremely relaxed upwelling for 

 this time of yea r . 



The pattern of negative anomalies corresponded in time and in 

 Location with a rapid warming of surface water during fall and 

 The intensity of warning was indicated by December sea 

 temperature anomalies 2C warmer than the 1946-67 mean* 

 than 3C warmer than the temperatures during the 1975 

 season.' Relaxed upwelling (i.e./ small values of 



winter . 

 surface 

 and more 

 winter 



offshore transport) is correlated with northward surface flow 



'fishJDa 



Fisheries 



I M 2 £ 2! § t i Q D ' 

 Center^ NMFS/ 



No. 12/ December 1976. 

 NOAA/ La JoLLa/ CA 92038. 



Sout hea St 



69 



