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Human Impacts

Bayou-Diversity (29 January 2019) On the surface it doesn’t seem possible. How can we catch all the fish in the seas? Analogies do exist.

Bison were once the most numerous single species of large wild mammal on the planet. They blanketed the Great Plains of North America and were the life-blood of Plains Indian societies for thousands of years. During the 19th century commercial hunters spurred on by government policies aimed at subduing Native Americans by eliminating their food supplies killed more than 50 million bison. The once vast herds were reduced to a few hundred individuals. In Louisiana bison were common and frequently mentioned by colonial era writers. The last known individual in the state was killed near present day Monroe in 1803.

Similarly, passenger pigeons were once the most common bird in North America. An estimated five billion passenger pigeons were found on the continent when Europeans arrived. During migration, flocks 1 mile wide and 300 miles long were recorded, taking several days to pass a fixed location. Again during the 19th century the species went from being one of the most abundant birds in the world to extinction as a result of market hunting and human-induced habitat loss. The last record of passenger pigeons in Louisiana occurred near Mer Rouge in 1903, exactly 100 years after the last bison.

No doubt people who witnessed the immense herds of bison and flocks of passenger pigeons thought their numbers inexhaustible. Now consider the fish in the seas. Recent studies have shown that within all of the world’s large marine ecosystems 29 percent of the species “had been fished so heavily or were so affected by pollution or habitat loss that they were down to 10 percent of previous levels.” This meets the definition of a collapsed fishery. Cod have been reduced to between 1% and 3% of their natural abundance, and Atlantic bluefin tuna populations have declined 90% since 1970. On this course a global collapse of most commercial species is predicted by 2048 if conservation actions are not taken.

Humans do indeed have the capability and the indifference to completely eliminate a species from our planet. With the ongoing political assault on bedrock conservation laws as evidence, the situation is unfortunately only getting worse.


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