Fig. 1: Scales of protection generated by pirarucu co-management in Amazonia.

a, Illustration elucidating the landscape where territorial protection and surveillance are implemented. Protection extends far beyond oxbow lakes, covering substantially larger areas. Pirarucu co-management activities have varying impacts at different spatial scales: (1) direct scale of protection—immediate lake areas under surveillance; (2) effective scale of protection—full-time territorial surveillance, intensified during the dry season, protecting areas of management interest; (3) functional scale of protection—estimated on the basis of the movement ecology of pirarucu, considering their ability to sustain ecological interactions; and (4) incidental scale of protection—indirect surveillance of adjacent upland forest areas that are incidentally protected by restricting access to the floodplain by outside users. b, Left, mid-section of the Juruá River, western Brazilian Amazonia. Orange circles represent 14 communities located within two contiguous sustainable-use forest reserves, with a combined area of 886,176 ha. These communities perform territorial surveillance for co-management of pirarucu (A. gigas) fisheries within 96 lakes (indicated by blue dots). Right, shows (1) the effective scale of protection (in yellow), which included to the routes that community rangers patrol to protect lakes and (2) the scale of functional protection (shaded in orange), in which pirarucu stocks are fully protected to move into floodplains during the high-water season. Finally, the wider (3) scale of incidental protection (shaded in grey) represents the adjacent upland (terra firme) forests that are also closed off by restricting access by outsiders into floodplain forests.