One of the most exciting scientific findings of the past half century has been the discovery of widespread trophic cascades. A trophic cascade is an ecological process which starts at the top of the food chain and tumbles all the way down to the bottom.
We all know that whales eat fish and krill, and some people – certain politicians in Japan for example - have argued that killing whales would be good for human beings, as it would boost the food available for us to eat. And so you would think.
But as the great whales declined, so did the numbers of fish and krill. It seems counter-intuitive: surely their numbers would rise as their major predators disappeared? But it now turns out that whales not only eat these animals; they also keep them alive. In fact they help to sustain the entire living system of the oceans.
Whales feed at depth, in waters that are often pitch dark. Then they return to the surface: to the phot