A scuba diver photographs tuna as they swim into a tonnara—a maze of fixed nets—off Carliforte Island, Sardinia, Italy. The tonnara nets are part of an ancient fishing method, now practiced in only a few locations around the Mediterranean. The fish are channeled into a part of the maze from which they cannot retreat, and from where they can be hoisted onto boats, and slaughtered by hand. The killing, known as la mattanza, is surrounded by age-old tradition and ceremony. The fish—northern blue-fin or Mediterranean tuna—are at the end of a long migration, and can be up to 400 kilograms in weight. Tonnara fishing is a more sustainable technique than other methods of catching tuna, such as trawling. It is dying out not only because it is so labor-intensive, but because pollution and large-scale commercial fishing have diminished stocks.