-28The 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 o*
variation (v), may be due to several causes, prominent of vhi:h
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.