Interesting near-future idea of humans herding whales for use as meat. Lots of solid science, especialy ecological principles, for a book writtne in 1957. Clarke has always been good at writing hard science fiction.
From the back cover: He was a misfit - a space ship engineer who had developed such fear of outer space that he could no longer function. Permanently separated from his wife and children on Mars, he faced a terrible future back on Earth - unless through psychiatry he could create a new life as a warden of the oceans' depths.