A Preliminary Study on Protease Activity of the Northern Pike (Esox lucius L. 1758) Larvae

摘要

The proteolitic activity of northern pike prelarvae was measured in yolk sac stage to reveal the critical first feeding time at relatively high incubation temperature. The differences observed among protease activities of larvae from day after hatching (DAH) 0 to 12 were statistically significant (P<0.05). Protease activities of larvae remained slightly increased from DAH 0 to DAH 5. A sudden raise in protease activities of larvae were observed from the DAH 6 to the DAH 8. Moreover, the conspicuous increase in protease activities of pike larvae was determined at the DAH 8 (595.22±9.07 U/mg protein). All starving larvae died four days after yolk sac consumption. In conclusion, to prevent tissue breakdown, larvae should be fed immediately just afteryolk sac absorption at the DAH 8 at 13°C under controlled conditions.