I'm new to permaculture and just started Bill Mollison's manual. In chapter 2.7, he says" if the frog eats 10 kg of grasshoppers to make one kilo of frog, it doesn't keep the 10 kg in a bag, but excretes 9kg or more back to earth as manure"
He also says "so now, the carp (at 80 years old and 10kg weight) has eaten 100x10kg = 1000kg of frogs and insects, and has returned 990kg of digested material per year back to the pond, to grow more herbage"
But don't these statements ignore resparation, which results in a large amount of carbon entering the atmosphere as C02? Plus lots of energy was expended. In other words, after an animal stops growing isn't it a drag on the system? Yes it may increase plant fertility but he doesn't mention that, simply claiming that the fully grown animals are simply recyclers of nutrients. But aren't they doing the exact opposite of our goal as farmers, which is to harvest energy from the sun and carbon from the atmosphere?