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The rate of decline of the radioactivity in almost all of
the fish was greatest during the first 100 days, during which
time more than 90 percent of the post-shot radioactivity was
lost.
The variation in amounts of radioactivity in tissues from
the same collection of fish, as measured by the coefficient of
variation (v), may be due to several causes,
prominent of which
are the differences between different species of fish.
The vari-
ations definitely indicate that large samples of many species
are necessary to obtain reliable information on the amount of
radioactive materials present in fish populations.