260 



FISHERY BtlLLETDSr OF THE FISH AND WILDLIFE SERVICE 



Figure 7. — Relation of A,- (the difference between ob- 

 served and estimated numbers of jack mackerel eggs) 

 and the number of eggs observed at the ith station. 



compared with the number actually observed and 

 the difference (A,) noted. (A( = the standard num- 

 ber of jack mackerel eggs estimated by linear 



interpolation minus the number actually ob- 

 served.) The differences were averaged to give 

 a mean difference (A) between the estimated num- 

 ber of eggs and the actual number of eggs. The 

 average difference (A) was minus 11, with a vari- 

 ance of 3370. The 95-percent confidence hmits 

 on A are minus 47 to plus 25. 



Although the individual errors arising from the 

 practice of linear interpolation of jack mackerel 

 eggs in time and space were high and variable, the 

 average error tended toward zero. I concluded 

 that for a large number of samples (i.e., inter- 

 polations) the error arising from linear interpola- 

 tion of the number of eggs in time and space was 

 negligible. 



A further indication of irregularities in the 

 spatial and/or temporal distribution would be the 

 nonconcurrence of eggs and larvae in the sampling 

 areas. In table 11 the occurrences of eggs and 

 larvae, by regions, are compared. In region 1, 



Table 11. — Occurrences of jack mackerel eggs and larvae, by month and region, 1952-54 



> See page 2S3. 



