The over utilization of a species of organisms occurs when the organisms are killed for purposes such as food or trade of their body parts, but their killing is uncontrolled and their populations are not allowed to recover.
Poaching brings about over utilization very quickly, as poaching is an illegal activity so poachers do not respect regulations in terms of killing organisms. Moreover, poachers kill organisms in very large numbers, meaning that every single poacher leaves a huge impact on the population of the specie.