ONTOGENETIC CHANGES OF LEARNING CAPABILITY AND STRESS RECOVERY IN PACIFIC THREADFIN JUVENILE

Reiji Masuda and David A. Ziemann

The Oceanic Institute, 41-202 Kalanianaole Hwy.,
Waimanalo, HI 96795 USA
ziemannda@oceanicinstitute.org

Journal of Fish Biology (2000) 56 : 1239-1247

Time taken by Pacific threadfin Polydactylus sexfilis juveniles to learn a conditioning reward was taken as the criterion for learning capability. Fish of 50 mm and 90 mm LF had a better learning capability than did smaller (22 mm, 36 mm) or larger (130 mm) size classes. Larger fish (90 mm and 130 mm) were quicker to recover from handling stress than were smaller fish. Based in these experiments it is suggested that 90 mm size class should have the highest adaptability when released into the wild.