Early accounts of the abundance of fish and wildlife offer us a window to the past that helps reveal the magnitude of subsequent declines. They provide us with benchmarks against which we can compare the condition of today's seas. Such benchmarks are valuable in countering the phenomenon of shifting environmental baselines, whereby each generation comes to view the environment into which it was born as natural, or normal. Shifting environmental baselines cause a collective societal amnesia in which gradual deterioration of the environment and depletion of wildlife populations pass almost unnoticed. Our expectations diminish with time, and with them goes our will to do something about the losses.
Callum Roberts, The Unnatural History of the Sea
environment