Abstract: Measures for controlling nuisance-carp populations include a harvest apparatus for harvesting not sub-surface fish but fish that leap out of the water proximate the harvest apparatus. Detectors detect when subsurface fish are within proximity of the effective range of the harvest apparatus and, when such are detected, a stimulus is applied which causes target fish like nuisance carp but not desirable fish to leap out of the water. When that happens, the harvest apparatus takes its toll on the leaping fish, harmlessly to the desirable fish which do not leap, and instead might flee from the stimulus by diving deeper.