The lsraeli Joumal of Aquaculture - Bamidgeh 50(2), 1998, 60-66
THE EFFECT OF THYROXINE ON THE GROWTH AND YOLK
RESORPTION OF CHUM SALMON (ONCORHYNCHUS KETA)
YOLK SAC LARVAE
Department of Marine Living Resources, Kunsan Nationa! University,
Kunsan 573-360, Korea
Chang lk Zhang
Department of Marine Production Management, Pukyong National University.
Pusan 608-737, Korea
(Received 25.6.97, Accepted 22.4.98)
Effects of immersion treatment of Na-L-thyroxine (T4) on chum salmon, Oncorhynchus keta, yolk-sac larvae were studied. Treatment experiments were carried out with various combinations of T4 concentration and treatment duration (0.1 ppm-60 min; 0.5 pprn-30 min, 60 min; 1.0 ppm-60 min) for 18 days, from 15 to 33 days after hatching. The T4 treatment caused a significant increase in the growth rate of the larvae. Treatment with thyroxine at 0.5 ppm for 60 min resulted in the most significant increase in total length and total weight. This treatment accelerated yolk-sac resorption and caused thickening of the epidermis.