Spatial and temporal variation of density and detectability of passive fishing gear in small stream systems

Objective We sought to quantify the density of passive fishing gear (e.g., trotlines, limblines, juglines) in low-order streams and identify the environmental factors influencing detectability. Methods From August 2023 to August 2024, we conducted systematic surveys in two streams in eastern Texas, USA, using fixed-interval transects. When encountered, the passive fishing gear was georeferenced and classified based on type (trotline, limbline, jugline) and status (active or abandoned based on visible condition, such as frayed lines, algal growth, or gear positioned out of water). Detection probability was modeled using hierarchical Bayesian regression with environmental covariates including river discharge, gauge height, precipitation, and time since first detection. Results Across 10.2 km of surveyed stream, a total of 151 passive fishing gears were found, over 80% were classified as abandoned, and none displayed legal gear tags. Gear densities varied seasonally, with the highest estimates in fall and winter–spring and the lowest in summer. Detection probability declined with increasing river discharge, gauge height, and time since first detection but increased with increasing precipitation. Passive fishing gear was not spatially clustered near access points (i.e., boat ramps). Conclusions This diffuse pattern, combined with the high rate of abandonment and absence of legal tags, underscores the limitations of current regulatory frameworks and the widespread noncompliance associated with passive fishing gear. These findings provide baseline information that is necessary for assessing regulatory effectiveness and potential ecological implications of passive fishing gear.