David McCandless examines our problem with over-fishing:
[Today] our fishing policies and environmental activism [are] geared to restoring the oceans to the state we remember they were. That's considered the environmental baseline. The problem is, the sea was already heavily exploited when we were young.
So this is a kind of collective social amnesia that allows over-exploitation to creep up and increase decade-by-decade without anyone truly questioning it. Today's fishing quotas and policies for example are attempting to reset fish stocks to the levels of ten or twenty years ago. But as you can see from the visualization, we were already plenty screwed back then.
The above map compares the biomass of popularly eaten fish in 1900 and 2000.
(Hat tip: Kottke)
The Dish 