Geographic and environmental causes of variations in meristic and morphometric characters were examined for the ten herring populations in the Far Eastern waters. A study of the correla tions between the characters of each population and the latitude, salinity and water temperature at the spawning grounds showed that five characters of initial growth, upper gill rakers, lower gill rakers, head length-body length relation and predorsal length-body length relation are closely related to the

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... de or water temperature, but showed no relation with the salinity in the spawning grounds. Three factors were extracted by factor analysis for the ten morphological characters in popula tions. One of them which seems to have no correlation with the three environmental properties examined is the factor suggesting genetic differences between the populations. The variations in morphological characteristics may be associated with each population's ecological, adaptitional and quantitative properties during their evolutional courses in the Pacific Ocean.