The ocean provides important living and nonliving resources. To be maintained for future use, these resources must be managed sustainably. Most fish are caught by lines or nets as they swim in the open waters of the ocean. Some species of fish are being over-harvested, which means their rate of reproduction cannot keep up with the rate at which people consume them. Bottom trawling is a method of fishing that involves towing a weighted net across the seafloor to harvest fish. In many areas where bottom trawling is done, ecosystems are severely disturbed by the large nets. For this reason, in a few areas in the world, laws limit bottom trawling to waters not more than 1,000 m deep or waters far from protected and sensitive areas. Still these actions protect some of the seafloor. Besides food, ocean organisms have other uses. Some provide us with medications.NONLIVING
Oil and natural gas are the most valuable non-living resources taken from the ocean. Extracting these resources requires drilling into the seafloor. Oil platforms have dozens of oil wells that are drilled in places where the ocean is sometimes 2,000 m deep. A description of the Deepwater Horizon oil spill affecting the Gulf of Mexico is located in the Human Actions and Earth’s Waters chapter.The seafloor has some valuable minerals. Manganese nodules containing manganese, iron, copper, nickel, phosphate, and cobalt may be as small as a pea or as large as a basketball. Estimates are that there may be as much as 500 billion tons of nodules on the seafloor. The minerals in manganese nodules have many uses in the industrial world, but currently they are not being mined. Think back to the discussion of ore deposits in the Earth’s Minerals chapter. Why do you think these seafloor resources are not being mined?