A CHROMATIC ACTION SPECTRUM FOR PLANKTONIC PREDATION BY JUVENILE YELLOW PERCH, PERCA-FLAVESCENS

The intensity of light required for juvenile yellow perch, Perca flavescens, to strike at planktonic prey was determined at 14 wavelengths, particular attention being paid to the near-ultraviolet region of the spectrum. Juvenile yellow perch are known to possess near-ultraviolet-sensitive photoreceptors, which are absent in adults. The action spectrum obtained shows three peaks: one between 640 and 700 nm, one between 490 and 525 nm, and one in the near-ultraviolet range, between 360 and 400 nm. The relative amplitude of the near-ultraviolet peak is greater than the amplitudes of the other two peaks. These results reveal that juvenile yellow perch can detect and recognize prey using only near-ultraviolet visual cues. This finding is discussed in terms of the visual ecology of juvenile and adult yellow perch.