The effect of stervation on individual catchability and hook-avoidance learning of rainbow trout

Abstract

The effect of starvation on the individual catchability and hook-avoidance learning of the rainbow trout Oncorhynchus mykiss, was determined in angling experiments in outdoor tanks. The fish used were 215 mm in mean total length and were obtained from local fish farmers and grouped into two (K and Y) separate experimental tanks. Before the angling experiments, the K group was starved for 3 days, and the Y group for 10 days. Three subgroups from the K group and five subgroups from Y group were subjected to the capture-recapture method to test the individual catchability and hook-avoidance learning. Probability analysis of the results indicated that the K group showed differences in individual catchability but did not learn to avoid hooks, whereas the Y group showed the reverse. Another subgroup from the Y group was subjected to a test with the capture-recruit method, in which angled fish were replaced with naive ones, however these still showed no difference in individual catchability. Therefore, a period of starvation does affect the individual catchability and hook-avoidance learning of rainbow trout, but the mechanism underlying this has yet to be determined.