High seas waters are becoming less productive, requiring longer fishing voyages to produce the same volume of catch. Zeller co-authored a recently published paper showing that boats now catch one third the fish they did per distance travelled compared to 70 years ago, and a recent study led by Sala found that more than half of fishing efforts in international waters would not be profitable if national governments didn’t subsidise the boats with cash handouts. Most of these subsidies are given to large industrial-sized vessels. A ban could also eliminate unfair market advantages of large fishing boats able to make longer voyages and, Sala says, could reduce the frequency of forced labour on unwatched vessels.