adults over 5 or 6 years of apeo Usually the fall season has been longer 

 than the winter season and direct suiranation of samples would heavily weight 

 the young adults. Judging from preliminary computations, which indicate 

 greater abundance -» more marked a decade or more ago than at present - in 

 the winter when the old adults are dominant, weighting in the opposite 

 direction would be more appropriate. Obviously, these phenomena need be 

 taken into account in combining the samples for the two parts of the fish- 

 ing season. 



Compute regional weights. - The sardine at different ages tends to 

 frequent different places along the Pacific coast (F. W. Clark 1940 pp. 

 44-46). In general, smaller individuals prevail in the south and larger 

 ones in the north, with many exceptions in detail. Hence, the fishery 

 at any one port does not afford a true cross -section of the entire popu- 

 lation. To get that, samples from the different ports must be combined 

 in proper ratios. Logically they should be weighted in proportion to the 

 fraction of the total population available from each port. As these frac- 

 tions differ from one part of the season to another, and in any case are 

 difficult to determine, the computation of regional weights is no simple 

 task. 



In general, the basis for such weighting might reasonably be the 

 estimate of relative abundance provided by the catch-per-boat-week. But 

 the method by which this statistic has been computed uses a different yard- 

 stick at each port. That standard must be calibrated by some kind of 

 detennination of the relative fishing capacities of the boats in the fleet 

 of each port. This project is under development but has not been 

 advanced to the point where its usability is assured. 



Another measure for determining the weighting for each port might 

 be derived from the statistical analysis of tagged-fish returns. It would 

 depend on computing the proportional amount that tagged fish are diluted 

 by release in the population of each fishing region. Certain difficulties 

 common to many tagging computations have so far prevented its use; but 

 its desirability is indicated hj the broken line running from "Statistical 

 analysis'* of the tagging procedural line to ** Compute regional weights." 



Combine samples. - At present, alternate ways of combining samples 

 are under consideration. The first and simplest plan assumes that the 

 weightings have fully discounted variations in availability so that a 

 simple summation of weighted samples will suffice to give seasonal fre- 

 quency distributions that will portray relative abimdance of each size 

 class and shovr the relative abundance of all commercial sizes from one 

 season to another. As before stated, however, there is reason to distrust 

 this assumption and unless farther considerations dictate otherwise, an 

 alternative will be adopted. 



The second plan does not require assumptions as to whether the weighted 

 samples represent relative availability or abundance. It is designed to 

 provide an adjustment converting availability to abundance that will not 

 produce erroneous results even if availability is not afactor to be dis- 

 counted. In essence, it is a method of selecting among the weighted samples 



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