A Somali fisherman carries a fish to the market near the port in Mogadishu. One of the U.N. Sustainable Development Goals calls for the world to "conserve and sustainably use the oceans, seas and marine resources for sustainable development."
Mohamed Abdiwahab/AFP/Getty Images
Crew members pull an oyster dredge in Tangier Sound of the Chesapeake Bay near Deal Island, Md., in 2013. A study found that the Chesapeake Bay shellfishery is a "hot zone" for ocean acidification.