Overexploitation

Overexploitation, also called overharvesting or ecological overshoot, refers to harvesting a renewable resource to the point of diminishing returns.

The term applies to natural resources such as water aquifers, grazing pastures and forests, wild medicinal plants, fish stocks and other wildlife.

The concern about overexploitation, while relatively recent in the annals of modern environmental awareness, traces back to ancient practices embedded in human history.

Contrary to the notion that overexploitation is an exclusively contemporary issue, the phenomenon has been documented for millennia and is not limited to human activities alone.

Historical evidence reveals that various cultures and societies have engaged in practices leading to the overuse of natural resources, sometimes with drastic consequences.

One poignant example can be found in the ceremonial cloaks of Hawaiian kings, which were adorned with the feathers of the now-extinct mamo bird.

Crafting a single cloak required the feathers of approximately 70,000 adult mamo birds, illustrating a staggering scale of resource extraction that ultimately contributed to its extinction.

The dodo, a flightless bird, exhibited a lack of fear toward predators, including humans, making it exceptionally vulnerable to hunting.

The dodo's naivety and the absence of natural defenses against human hunters and introduced species led to its rapid extinction.

This case offers insight into how certain species, particularly those isolated on islands, can be disproportionately affected by human activities due to their evolutionary adaptations.

By 1500 AD, a mere 200 years after the first human settlements, ten species of the giant moa birds were driven to extinction by the Māori.

This rapid extinction underscores the significant impact humans can have on native wildlife, especially in isolated ecosystems like New Zealand.

The Māori, relying on the moa as a primary food source and for resources such as feathers and bones, hunted these birds extensively.

This event serves as a cautionary tale about the delicate balance between human activity and biodiversity and highlights the potential consequences of over-hunting and habitat destruction.

The European settlement period serves as a poignant example of how human activities can drastically impact natural ecosystems.

[16] It was based on a parable that William Forster Lloyd published in 1833 to explain how individuals innocently acting in their own self-interest can overexploit, and destroy, a resource that they all share.

[17][pages needed] Lloyd described a simplified hypothetical situation based on medieval land tenure in Europe.

[16]: 1244 In the course of his essay, Hardin develops the theme, drawing in many examples of latter day commons, such as national parks, the atmosphere, oceans, rivers and fish stocks.

[18] A major theme running through the essay is the growth of human populations, with the Earth's finite resources being the general common.

This point is called the maximum sustainable yield, and in practice, usually occurs when the fishery has been fished down to about 30% of the biomass it had before harvesting started.

This turns much of the world's underground water and lakes into finite resources with peak usage debates similar to oil.

West Africa, Madagascar, Southeast Asia and many other regions have experienced lower revenue because of overexploitation and the consequent declining timber harvests.

Overexploitation of these resources for protracted periods can deplete natural stocks to the point where they are unable to recover within a short time frame.

[46] In practical terms, if continued, it reduces valuable resources to such low levels that their exploitation is no longer sustainable and can lead to the extinction of a species, in addition to having dramatic, unforeseen effects, on the ecosystem.

[47] Overexploitation often occurs rapidly as markets open, utilising previously untapped resources, or locally used species.

Island endemic populations are more prone to extinction from overexploitation, as they often exist at low densities with reduced reproductive rates.

[51] As another example, when the humble hedgehog was introduced to the Scottish island of Uist, the population greatly expanded and took to consuming and overexploiting shorebird eggs, with drastic consequences for their breeding success.

With civil unrest, for example in the Congo and Rwanda, firearms have become common and the breakdown of food distribution networks in such countries leaves the resources of the natural environment vulnerable.

In turn, the unchecked prey can then overexploit their own food resources until population numbers dwindle, possibly to the point of extinction.

Starting before the 17th century and not phased out until 1911, sea otters were hunted aggressively for their exceptionally warm and valuable pelts, which could fetch up to $2500 US.