Rapid Cold-Branding of Salmon and Trout with Liquid Nitrogen

Abstract

Liquid nitrogen (at −196 C) was successfully used as a coolant in a simple, inexpensive, and rapid method of marking salmon and trout with a metal branding tool. The marks, applied to as many as 650 fish per hour per marker, were consistently clear and readily identifiable for at least 14 months after application. No mortalities could be attributed to the branding technique among 4000 yearling coho salmon held for 2 months after marking.