Mapping and visualization of habitat structure (depth and submerged macrophytes) in relation to habitat choice of pike (Esox lucius) in a natural lake

Northern pike Esox lucius is a popular fish species amongst anglers. It displays diel behavioral patterns and is known for its strong affinity to structured habitats. Mapping of underwater structures and fish tracking in natural environments are technologically challenging, which limits our understanding of the fine-scale behaviour of pike. In this study, we applied hydroacoustics to survey the habitat structure (depth and coverage by submerged macrophytes) in a small natural lake (25 ha) in Brandenburg, and used a §-D telemetry system to track fish at high resolution. Datasets were interfaced in a geographic information system (GIS). The habitat maps were highly accurate and showed a preference of pike for shallower parts of the lake, vicinity to the lake ground and submerged macrophytes. At night, pike stayed significantly closer to the ground than during dawn. The data also validated pronounced home ranges of selected individuals. Despite its frequent use in behavioural ecology, the potentials of GIS to study fine-scale behaviour of fish are not fully explored.