How High Can Brook Trout Jump? A Laboratory Evaluation of Brook Trout Jumping Performance

Abstract

AbstractQuantitative data on how high brook trout Salvelinus fontinalis can jump are crucial for efforts by fisheries managers to exclude brook trout from streams containing native cutthroat trout Oncorhynchus clarkii subspp. and to build effective fishways for brook trout migration. We identified factors that could influence brook trout jumping ability and demonstrated how this knowledge could be applied to improve the design of barriers to brook trout migration or fishways to facilitate their migration. Our objective was to measure brook trout jumping performance under laboratory conditions to identify design features for constructing waterfall‐type barriers or pool‐and‐weir‐type fishways. We used flashboard‐type and flume‐type adjustable waterfall devices to measure brook trout jumping performance at various combinations of vertical or waterfall height (13.5–93.5 cm in 10‐cm increments) and plunge pool depth (10–60 cm in 10‐cm increments) over a 24‐h interval. We tested three size‐classes of brook trout: 10–15 cm total length (TL) (mean ± SD: 13.09 ± 1.67 cm), 15–20 cm (19.30 ± 1.19 cm), and 20 cm or more (26.52 ± 2.13 cm). The 10–15‐cm brook trout could jump a 63.5‐cm‐high waterfall, equivalent to 4.7 times their body length, from a 50‐cm‐deep plunge pool, which was 3.7 times their body length. Larger size‐classes were capable of jumping 73.5‐cm waterfalls, or 2.9–4.0 times their body length, provided the plunge pools were at least 40 cm deep (>1.6 times their body lengths). Shallow plunge pools (10 cm) prevented brook trout from all size‐classes from jumping waterfalls 43.5 cm or more in height. Small fish were capable of jumping a greater number of body lengths over vertical obstacles than large fish. The data analyses identified vertical height, plunge pool depth, fish total length, and fish condition as factors important in predicting brook trout jumping performance.