A tagging method for the sea urchin Strongylocentrotus nudus (A. Agassiz) with Coded Wire Tag

Usefulness of Coded Wire Tag made of stainless steel for the sea urchin Str ongylocentrotus nudus (A. Agassiz) was examined by rearing experiments. Tag s were inserted in the peripharyngeal cavity of sea urchins. Effects of tag ging on the growth and mortality were not found. The lost tags in % for 7 d ays increased for the first 14 days after tagging, showing size-dependent d ifference, and thereafter abruptly declined and kept a low Value after 21st day, without showing difference among size class. Estimation of the % of l ost tags for any time became possible using a regression equation of the ac cumulated % of lost tags on the elapsed day from the 21st day after tagging .