After fishing of the orange roughy, a deepwater fish, started, populations collapsed within 15 years (Image: Kim Westerskov/Getty) In an autumnal ritual as unvarying as migrating geese, European Union officials head back to Brussels next week – to fight over fish. But this time they might protect Europe’s richest and most threatened ecosystem, the deep seabed. They will discuss proposals to ban deep-sea trawling. Now in the first study of its kind, researchers have discovered…