Ecohydraulics of Nature-Like Fishways and Applications in Arctic Aquatic Ecosystem Connectivity
Bibliographic record
Abstract
Northern Canada is currently undergoing rapid mineral extraction development. As part of this development there is a need to perform fish habitat compensation projects and build effective fish passage facilities. There is currently limited information available on the hydraulics of nature-like fishways, as well as the behaviour of fish within these structures. Two studies were conducted: one laboratory study and one field study to improve the understanding of ecohydraulics and fish behaviour in nature-like fishways. In the laboratory study a pool-weir style fishway was constructed using both natural rocks and concrete spheres. Weirs were constructed in a flume with one of three geometries: v-facing upstream, v-facing downstream, and horizontal. For the v-shaped weirs an angle of 140 degrees was used on the inside of the v. The aim of this experiment was to examine the influences of slope, discharge, and weir geometry on horizontal velocity, vertical velocity, turbulent kinetic energy, turbulence intensity, Reynolds stresses, and volumetric power dissipation in rock-weir fishways. An acoustic Doppler velocimeter (ADV) and point gauge were used to measure velocity and water surface profiles, respectively, for discharges between 30 and 150 l/s at bed slopes between 1.5% and 5.0%. An effective operating range was identified for the proposed fishway design and a diagram was developed to aid designers in selecting appropriate discharge and bed slopes based on volumetric power dissipation. Two flow regimes were observed: plunging and transitional. A stage-discharge relationship was also developed to provide an improved estimate of discharge when compared with existing equations. Finally, a new method of weir construction was proposed that allows rock-weirs to be constructed off site, reducing installation time and resulting in a more flexible final design. In the field study the performance of a habitat connectivity project in the Canadian Barrenlands was evaluated where a stream was modified through the construction of nature-like fishway structures to increase habitat connectivity for Arctic Grayling (Thymallus arcticus). Under this project the total length of West Island Stream (WIS) was increased from 430 to 470 m and the slope of a steep cascade section deemed a barrier to fish passage was reduced. Five pools were selected in the steep lower-reach of WIS to evaluate for resting suitability for Arctic Grayling. A diesel pump was used to manipulate the flow in WIS (1.0, 9.9, and 21.9 l/s) and an acoustic Doppler velocimeter to measure point velocities within each study pool. Adult Arctic Grayling were placed in the pools and their resting behaviour was observed under each flow condition using visual fish surveys and video recordings. This study showed that stream-scale flow manipulation can be an effective tool in evaluating habitat compensation projects. The results indicated that only one of the study pools would provide acceptable resting habitat during all flow conditions expected during spawning. Based on the observations of the use of pools by fish, it is recommended that future resting pools for Artic Grayling have a minimum surface area of 1.4 m2, a minimum depth of 0.6 m, horizontal velocity magnitudes less than 0.2 m/s, and near-zero vertical velocities.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".