The enclosures stretch the length of an Olympic-size swimming pool, but from above they appear as floating dots scattered across the ocean. Inside, fish mill about as the submerged pens sway to the currents of the open sea.
Known as offshore fish farms, these structures have appeared around the world in recent years. Their proliferation in open waters, often sitting several miles off coastlines, has sparked heated debate: some see them as the next frontier for the sustainable production of fish such as Atlantic salmon, seabass and cobia; others describe them as “factory farming of the sea”.
