The “hot spot map” indicates areas of potential high concentrations of debris derived from past debris collection locations (Fig. 3a–d). The high probability occurrence zones (value: 24–27) comprised 49%, or 164 km2, of the 332 km2 study area (Fig. 3c). The medium probability occurrence zones (value: 18–23) comprised 33%, or 108 km2. The low probability occurrence zones (value: 11–17) and remote probability occurrence zones (value: 1–10) comprised the remainder of the study area.