From Bertolt Brecht's Tales from the Calendar

'If Sharks were people,' the landlady's daughter asked Mr K, would they be nicer to the little fishes?'

'Certainly', he said. 'If sharks were people they would have enormous boxes built in the sea for the little fishes with all sorts of things for them to eat in them, plants as well as animal matter. They would see to it that the boxes always had fresh water and, in general, the hygienic measures of all kinds. For instance, if a little fish injured one of its fins, it would be bandaged at once, so that the sharks should not be deprived of it by an untimely death. To prevent the little fishes from growing depressed there would be big water festivals from time to time, for happy little fish taste better than miserable ones...

'Moreover, if sharks were people, not all little fishes would be equal any more as they are now. Some of them would be given positions and be set over the others. The slightly bigger ones would even be allowed to gobble up the smaller ones. That would give nothing but pleasure to the sharks, since they would more often get larger morsels for themselves. And the bigger little fishes, those holding positions, would be responsible for keeping order among the little fishes, become teachers, officers, box-building engineers and so on. In short, the sea would only start being civilized if sharks were people.'

From Tales from the Calendar by Bertolt Brecht, tr. Y. Kapp.

See also Ian Birchall's review of Beware of Vegetarian Sharks by Richard Greeman.