RECORD OF SARDINE EGGS, 1956 



A record of all hauls containing sardine eggs in 1956 is given in table 

 II. As in previous reports, the eggs are divided into two categories, normal 

 and abnormal. The number of normal eggs taken at each station is reported by 

 age in days (A to D; see below). "Total number of eggs" includes abnormal as 

 well as normal eggs, and also deteriorating eggs that cannot be classified with 

 certainty. Abnormal eggs have embryos that are stunted and misshapen, either 

 due to mechanical injury during collection (rupture of the vitelline membrane) 

 or to a diseased condition of the eggs. 



The eggs are separated into age categories, as follows: 



A - Eggs spawned within 24 hours of collection 

 B - Eggs spawned within 24.1 to 48 hours of collection 

 C - Eggs spawned within 48.1 to 72 hours of collection 

 D - Eggs spawned within 72.1 to 96 hours of collection 

 Unclassified eggs (Unci.) includes deteriorating eggs that cannot be 

 classified with certainty. 



A dash (-) in table II indicates that the category (D day eggs, usually) 

 was not represented, actually or potentially. Rate of development of sardine 

 eggs is related to the temperature at which development takes place. Sardine 

 eggs take approximately 4.0 days to develop from spawning to hatching at 12.6°C, 

 3.0 days at 14.8°C, 2.0 days at 17.9*0, etc. Samples collected at temperatures 

 between 12.6-14.8°C may contain sardine eggs from either 3 or 4 days*spawning, 

 depending upon the time of collection. Similarly, samples collected at tempera- 

 tures between 14.8-17.9°C may contain eggs from either 2 or 3 days' spawning, 

 and samples collected at temperatures above 17.9°C may contain eggs from either 

 1 or 2 days' spawning. Sardines are seldom taken at temperatures high enough 

 to permit embryonic development to be completed in less than one day. 



The distribution and relative abundance of sardine eggs in 1956 are illus- 

 trated in figure 2. Five categories of abundance are used: - zero spawning 

 (station occupancy indicated only); light spawning, 1-30 eggs; moderate spawn- 

 ing, 31-300 eggs; moderately heavy spawning, 301-3000 eggs; and heavy spawning, 

 over 3,000 eggs. The value shown for each station is the cumulative standard 

 haul total for the year. 



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

 summarized by month and area in text table 3. No sardine eggs were obtained 

 off central or northern California (lines 40-77) in the 166 plankton hauls 

 taken in this area between April and July. Sardine eggs were taken in two of 

 the 76 hauls made off southern Baja California. The number of positive hauls 

 was highest off northern Baja California (lines 97-107), where 19.3% of the 

 hauls taken during the year contained sardine eggs. The percent of positive 

 hauls taken in other areas was as follows: southern (^lifornia (lines 80-93) - 

 7.1%, upper central Baja California (lines 110-120) - 15.2%, and lower central 

 Baja California (lines 123-137) - 7.2%. 



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