Integrating fish tracking technology and standardized netting protocols to refine fish abundance estimates

Abstract

Understanding fish availability to standardized sampling gear is essential for producing accurate population estimates in inland fisheries. This study investigates species-specific accessibility to bottom-set gill nets used in Ontario’s Broad-scale Monitoring (BsM) program by integrating standardized netting surveys with high-resolution acoustic telemetry. Focusing on Smoke and Canoe Lakes in Algonquin Provincial Park, this research evaluates how thermal stratification, lake morphometry, and species behavior affect the vertical distribution of lake trout (Salvelinus namaycush), white sucker (Catostomus commersonii), and smallmouth bass (Micropterus dolomieu) during the summer stratified period. A modified BsM protocol was implemented using short-duration, multi-pass netting paired with fine-scale acoustic telemetry arrays. Bayesian hierarchical occupancy, detection, and N-mixture models were applied to quantify lake bottom habitat use, gear detectability, and relative abundance. Results reveal distinct patterns in vertical habitat use that influence species’ availability to bottom-set nets. Lake trout and smallmouth bass frequently occupied midwater or pelagic zones, particularly in deeper basins, making them less accessible to netting gear, whereas white sucker showed strong overlap with bottom habitat and high detection probabilities. Differences in species distributions between lakes were also observed, influenced by variation in morphometry and thermal structure. Telemetry-derived availability metrics provided critical insights into vertical separation from gear and informed refinements to abundance estimates derived from netting data. By linking species behavior and lake characteristics with gear performance, this study highlights the importance of accounting for vertical distribution and detection bias in standardized surveys. These findings support the development of more ecologically informed fisheries monitoring strategies and underscores the value of integrating telemetry with traditional netting to improve population assessments in Ontario’s inland lake systems.