Rock Bass Learn to Associate Food with a Visual Cue and Remember the Association When Food Is Absent

Abstract

ABSTRACT We explored the foraging ability of rock bass (Ambloplites rupestris) by testing three hypotheses consistent with the predictions of optimal foraging theory: 1) fish can learn to associate food with a visual cue; 2) trained fish will go to a visual cue faster than untrained fish; and 3) over time, without the reinforcement of food, trained fish will exhibit a diminished response to a visual cue. Our results supported each hypothesis. During the first 96 h of testing, 88 to 100% of trained fish went to the visual cue first; 50% of the trained fish went to the visual cue first after 312 h. None of the untrained fish went to the visual cue first. Trained fish went to the visual cue significantly faster (11.0 cm sec−1) than untrained (1.6 cm sec−1) fish. There were no significant differences in velocity to the visual cue among the times tested for control fish (0.8 to 2.6 cm sec−1). However, velocities of experimental fish were significantly higher from 0 to 24 h (16.7 cm sec−1) than from 48 to 312 h (6.7 cm sec−1), suggesting that they began extinguishing their responses as the time since the last food reward associated with the cue increased. If rock bass use these abilities in their natural habitats, they likely improve their foraging efficiency and, thus, their overall fitness.