I often hear quotes about how, 300 years ago, there were so many fish/whales/sharks in the ocean you could "walk on their backs". Does anyone know where I can read accounts of how abundant the oceans were more than 2 centuries ago?
For a decent popular text, I'll suggest Mark Kurlansky's Cod: A Biography of the Fish that Changed the World. It's an easy read and keeps the topic interesting.
It may be worth x-posting this question to /r/AskScience, in either the Biology or Earth & Planetary Science categories