APPENDIX: DESIGN OF A SARDINE TAGGING EXPERIMENT 



Purpose and Requirements 



A sardine tagging experiment pertinent to the sub -population problem must be designed to 

 answer the question: "What interchange is there, if any, between the space-time spawning groups?" 

 As an aid to the design of such an experiment we are fortunately able to draw upon two sets of in- 

 formation collected annually, primarily for other purposes . First, the location of the spawning 

 areas in space and time are known, and, second, estimates of the numbers of fish spawning in each 

 of these areas are available. (This statement does not apply at present to spawning in the Gulf of 

 California.) 



The question posed places two basic requirements upon such an experiment: 



1 . All tagging must be done on the several spawning grounds at spawning 

 time. 



2. All recoveries must be made on the several spawning grounds at 

 spawning time . 



It is desirable that several additional conditions be imposed upon the experiment, including: 



1 . The number of tags put out in each area will be proportional to the size 

 of the population in each area . 



2 . The recoveries in each area will be proportional to the size of the popula- 

 tion in each area . 



3 . Ten recoveries in a single area from tags put out in any single area is 

 the minimum number that will be accepted. 



Two Examples 



In an earlier section of this paper, the four possible space -time separations between spawn- 

 ing groups were described. They include (1) the southern California offshore area, (2) the Lower 

 California offshore area, (3) the Lower California inshore area and (4) the Gulf of California. Not 

 enough is known about spawning in the latter area for it to be profitably included in a tagging ex- 

 periment at this time. (However, two exploratory cruises into the Gulf are planned during 1956.) 



Considering only the first three areas, the sardine spawning groups in 1952 and 1953 were 

 distributed approximately in the following proportion: 



S. Calif, offshore 5% 



L. Calif, offshore 70% 



L. Calif, inshore 25% 



Now, if 20,000 tags are put out in proportion to the population distribution, then there will be 

 1,000, 14,000 and 5,000, respectively, tags out in these areas . 



9 

 With this many tags out, assume, for example, a total spawning population of 2 x 10 



fish. If these fish return to the same spaw.j ng areas the next season with no mixing or straying 



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