In the northern half of the spawning area (lines 80-107) in 1957, sardine 

 eggs were obtained at temperatures which averaged only O.S'C higher than during 

 the previous six years. In the southern half of the spawning area (lines 110-137), 

 water temperatures at the stations having sardine eggs averaged a full degree 

 higher during the main spawning period (January through June), and 2.7°C to S.O^C 

 higher during the late spawning period (July through October), Hence, the Increased 

 water temperatures during 1957 were reflected mainly in the southern half of the 

 spawning distribution. 



The distribution and relative abundance of sardine eggs in 1957 are illustrated 

 in figure 2. The abundance shown for each station represents the cumulative 

 standard haul total of sardine eggs at the station during the year. Stations (open 

 circles) without shading had no sardine eggs in the plankton hauls taken during the 

 year. 



Occurrences and abundance (standard haul totals) of sardine eggs are summar- 

 ized by month and area in text table 4. Sardine eggs were taken in fewer hauls 

 than in any recent year; occurrences during 1957 numbered 76, as compared to 144 

 in 1956, 186 in 1955, and 309 in 1954. The decrease in occurrences in 1957 reflects, 

 in part at least, a decrease in abundance of spawning sardines. Coverage of spawn- 

 ing areas was as thorough in 1957 as in preceding years, except 1954. (Coverage 

 in 1954 was more intensive than at any time before or since.) 



The distribution of spawning between the several subareas, however, has been 

 fairly similar during the past three seasons. This is shown in the following summary: 



1955 



1956 



1957 



Total 186 45,198 99.9 



144 98,327 100.0 



76 31,273 100,0 



It is convenient to divide sardine spawning Into two major centers: one off southern 

 California and northern Baja California (station lines 80-107), the other off central 

 Baja California (station lines 110-137), The two centers have been of about equal 

 importance in each of the above seasons. In 1955, 49 percent of the eggs were ob- 

 tained in the northern center; in 1956 the percentage was 46 percent; in 1957 it was 

 48 percent. 



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