There are ~4,000 offshore oil and gas platforms in the Gulf of Mexico. They produce one of the most prolific ecosystems, by area, on the planet. Stanley and Wilson (2000) reported that 10,000-30,000 adult fish reside around a platform in an area about half the size of a football field.
Live rock organisms, coral, endangered species, and "protected" fish and invertebrates colonize the platform’s submerged structure. Many blue-water platforms create complex coral reef ecosystems, comprised of Caribbean flora and fauna that would otherwise not exist on thousands of square miles of generally featureless and silty continental shelf. These platforms clearly produce fish rather than merely attract fish.
Over 50 species of federally managed fish, crustaceans, and live rock organisms settle and forage around the offshore structures. The ecosystems they create are not designated as "protected habitat" under any of our current Fisheries Management Plans. 200 platforms are scheduled to be removed every year for the next 20 years.