Fish and Fisheries

As the cause of dead zones became understood, research was devoted to figuring out the impact of hypoxia on aquatic life. The Gulf of Mexico dead zone overlaps with the Fertile Fisheries Crescent that stretches from Alabama to Texas, home to a multibillion dollar seafood industry. The chapter argues that the effect of hypoxic waters on benthic invertebrates is clear, while the story for mobile species like fish is complicated. Sessile invertebrates on the bottom, food for many fish and other animals, are wiped out when dissolved oxygen disappears. This chapter explains that even when mobile organisms are able to swim away to oxygen-rich waters, they are concentrated into a smaller habitat where they are more easily caught by predators and fishers. In the Gulf, the effects of hypoxia on fisheries are difficult to separate from the response of the fishing industry and overfishing, but effects especially on shrimp fisheries have been documented. As the chapter summarizes, hypoxia has many other impacts on aquatic biota, including rearranging food webs and contributing to the rise of jellyfish in coastal waters. Even when fishing yields are not affected, dead zones can devastate aquatic life and habitats.