Daily nocturnal homing reveals goal-directed navigation in a wild teleost

Understanding how free-ranging animals navigate large, low-visibility environments remains an important challenge in movement ecology. Using high-resolution acoustic telemetry, we investigated the movement behavior of adult pikeperch (Sander lucioperca) in a large freshwater reservoir. Individuals repeatedly left a stable resting place to forage across extensive areas and reliably homed back even after multi-kilometer nocturnal excursions lasting several hours. Return trajectories were initiated under dark or low-light conditions and were strongly oriented toward the refuge from the onset of movement. Bearings during the initial phase of return showed low deviation from the direct direction to the goal, and trajectories were characterized by stable swimming speeds and low tortuosity. Final approach distances were small relative to excursion scale, and returns were achieved without extended search behavior. Together, these patterns demonstrate consistent and repeatable daily homing under low-visibility conditions and are consistent with goal-directed navigation toward a fixed spatial target.