For a marine protected area, a line on the map is supposed to carry legal weight. It tells fishing vessels where they may not go. It tells managers where their authority begins. It tells governments what they have promised to protect. In the open ocean, that line can be hard to defend. Fish move through it. Currents cross it. Plastic and lost gear drift into it. A reserve may be closed to fishing vessels and still receive the debris of industrial fishing. A recent paper in Science Advances shows how serious that problem has become for one widely used fishing technology: drifting fish aggregating devices, or dFADs. These are floating rafts, often fitted with satellite buoys and echosounders, that help purse seine fleets find and catch tuna. Tuna and other species gather around floating objects. For fishing companies, dFADs make a mobile and unpredictable ocean easier to search. For protected areas, they create a different problem. A dFAD can be deployed outside a reserve, drift into it, aggregate fish, entangle wildlife, break apart, sink, or wash ashore on reefs and beaches. It can do this without a vessel crossing the boundary. It can also do it without being visible to managers, since buoy data are usually controlled by fishing companies. Intersection between 88,359 tracked dFAD buoys (pink) with existing MPAs showing where dFADs have likely entered (red) or not (blue); (E) MPAs and shark sanctuaries where dFAD strandings were identified with count (circle), observed but not counted (red diamond), or…This article was originally published on Mongabay