Title: Conquerors Darkness
First published: July 1979
Description: From the back cover:

The Earth has been transformed into a wtaery breeding ground for mutants and dreaded alien Star Beasts.  True humans are confined to island reservations or a life on the high seas.  Few ever escape the mundane life of island existence to join the mysterious Sea-Lords.

But one landsman, Dovirr Stargan, is determined to become a Sea-Lord, and he is willing to kill or die for the chance.  The brutal Star Beasts who devastated the Earth have been gone for many years, but the desire for vengeance is a living force among the Sea-Lords.  And when they do return to plant their eggs the Star Beasts must face the fury of the united forces of humanity... landsmen, Sea-Lords and mutants, and the new Ruler of the Nine Seas -- Dovirr Stargan.
Subjects: Science fiction, Fiction, science fiction, general
LC classification: PZ7.S5858 Co