Local fisheries conservation and management works: implications of migrations and site fidelity of Arapaima in the Lower Amazon

Effective conservation must account for fish migrations to minimize threats to freshwater fishes. Many floodplain fishes, like giant Neotropical arapaima (genus Arapaima), migrate laterally into seasonally flooded habitats to feed and reproduce. Effects of seasonal migrations on conservation efforts like community-based management remain uncertain. Acoustic telemetry was applied to arapaima in floodplain habitats (Lower Amazon) to characterize (1) lake fidelity, (2) lake population connectivity, and (3) migrations beyond managed units. During low water of 2014, 24 arapaima were captured and implanted with acoustic tags in three lakes within a 10-km diameter and across two fishing communities. During floods, the entire study area was connected, including tagging lakes. Monitoring was continuous over two annual flood cycles using an array of 19 fixed acoustic receivers in four lakes. Additional nearby lakes were surveyed with portable receivers for unaccounted individuals during subsequent dry seasons. On average, 74% of unharvested arapaima returned to the same lake; no arapaima were found outside their lake of tagging origin during subsequent dry seasons. During high water, arapaima migrations were not contained within community management units; three arapaima were found outside their community zone. Overlapping distributions of arapaima from each of three lake populations showed connectivity during flooding, especially near known spawning grounds. Results demonstrate that management by local fishers to regulate fishing within lakes can work because arapaima show fidelity to their lake of tagging origin. Current management efforts could be improved by delineating management units to networks of habitats that sustain arapaima over complete life histories.