Those documentaries are largely correct. Over 80% of the biomass of the oceans has been lost in the past century, and a substantively similar amount of non-human, non-domesticated vertebrate terrestrial biomass.
In the past 100 years, 80% of the biomass of fish in the world’s oceans has been lost, Christensen says in a AAAS video that coincided with a symposium at the Annual Meeting. “Just in the last 40 years, we have lost 60% of the biomass,” he explained. “So we’ve seen some very serious declines, and there’s no doubt about what the cause is: We’re talking about overfishing—overfishing at the global scale.”
I think this gets released after every cold spell on the east coast. I'm pretty sure I can correlate the actic vortex to various friendly reminders these climate people need to get paid.
"Researcher Reports Stunning Losses in Ocean Fish Biomass" 28 February 2011 Edward W. Lempinen http://www.aaas.org/news/researcher-reports-stunning-losses-...
In the past 100 years, 80% of the biomass of fish in the world’s oceans has been lost, Christensen says in a AAAS video that coincided with a symposium at the Annual Meeting. “Just in the last 40 years, we have lost 60% of the biomass,” he explained. “So we’ve seen some very serious declines, and there’s no doubt about what the cause is: We’re talking about overfishing—overfishing at the global scale.”
There's been a similar huge transformation in both the absolute and relative amounts of terrestrial vertebrate biomass, as plotted by +Paul Chefurka: https://www.facebook.com/photo.php?fbid=10152825071748824
See also: http://collapseofindustrialcivilization.com/tag/paul-chefurk...
His thermodynamic footprint article discusses related issues, though not specifically animal populations: http://www.paulchefurka.ca/TF.html