抄録
An outdoor-tank angling experiment was conducted for wild and domestic groups of Tilapia mossambica to clarify the cause of different catchabilities of fish. A series of release-recapture trials was conducted, in which angled fish were counted for release and subsequent recapture; three times for the wild group and twice for the domestic group. Angling experiences of individuals were examined based on the marks after each series. Pellets taken by fish were weighed after the experiment to examine the potential relationship between feeding intensity and catchability. It was significant that wild fish angled in the first trial were hooked repeatedly in the subsequent trials, while domestic fish were hooked at random in any trial, demonstrating that catchability can be altered by rearing. In addition, the catchable wild individuals were hooked quickly and the uncatchable fish remained unhooked for a longer period in each trial. Large fish took more pellets but there was no correlation between fish size and catchability, implying that the hierarchy in feeding is not related to differences in catchability. Individual differences in the catchability were ruled by precaution behavior, which may change with culture conditions.
