Over-exploitation Over-exploitation is when a species is hunted to the point where the population has decreased enough to be unstable. It is sometimes referred to as over-hunting or over-fishing. One example of this is the passenger pigeon. In the 19th century they were the most common birds in the world, but they were extinct by the early 20th century due to over-hunting. This is probably the most extreme example of over-hunting, but several other species are affected today. For example, the blue-fin, yellow-fin, and albacore tunas are all threatened or endangered due to over-fishing. Many experts estimate that the blue-fin tuna will be extinct within a decade.