Studies on the Method of Tagging

The corrosion resistance of the three kinds of wire (copper wire, tin-coated copper wire and enamel-coated copper wire) for the celluloid tags were tested by measuring their breaking stress, elongation and by examining the appearance of the surface of the wires after they were immersed in sea water for certain periods. In the tin-coated copper wire corrosion proceeded more rapidly than in the copper wire, and enamel-coated copper wire was much more resistant against corrosion. In the two former, corrosion proceeded by “local corrosion”. In cach kind of wire tested, thin wire was much less resistant against corrosion than thick one. No significant difference was seen between the corrosion resistance of the wire attached to the fish which was recaptured and that of the merely immersed wire (used for comparison). Enamel-coated copper wire scarcely underwent change in breaking stress and general appearance after the immersion into sea-water for 1 to 1 1/2years.