USE OF LANTHANIDE ELEMENTS TO MASS MARK JUVENILE SALMONIDS

Two experiments were conducted to evaluate the mass marking of coho salmon (Oncorhynchus kisutch) fry and smolts by the addition of lanthanide acetates to the water supply. The results demonstrated that lanthanides are absorbed from the water and are subsequently deposited in the vertebral column, otoliths, and scales of juvenile coho. Lanthanum and samarium applied at concentrations of 100 mug/L for 6 wk to fry resulted in the retention of detectable levels in bony tissues after 10.5 mo. When coho fry and smolts were exposed to various combinations of lanthanum and cerium at a total concentration in the water of 100 mug/L over a 4-wk period, residual mean amounts of lanthanides in the vertebral columns were greater in smolts than in fry.