Poor Upstream Passage for Endangered Atlantic Salmon (<i>Salmo salar</i>) at a Trap‐and‐Transport Fishway in the Wolastoq/Saint John River, New Brunswick
Bibliographic record
Abstract
ABSTRACT Declines of Atlantic salmon (Salmo salar) in the Wolastoq/Saint John River have largely coincided with hydropower development, and there is an urgent need to understand the status of bidirectional passage at existing barriers. We evaluated upstream passage efficiency and duration at the lowermost hydroelectric dam (Mactaquac Generating Station), which targets salmon for upstream passage with a manually operated fish lift and transport system. In a 2‐year study, we captured, tagged, and released upstream adult migrants within 500 m of the fishway and monitored their movements using PIT, radio, and acoustic telemetry. Overall, a low proportion (19%) of individuals that approached the dam passed upstream, and successful individuals experienced considerable passage delays (mean = 58 days) despite visiting the fishway on multiple occasions prior to passage (mean = 8 visits). Salmon were approximately 41 times more likely to visit the fishway entrance during daylight hours (92% of total fishway detections occurred during daylight), likely reflecting elevated power generation and flow conditions during daylight. Further, salmon were approximately five times more likely to visit the fishway entrance while the fishway was not operational (70% of fishway detections while not operating). Accordingly, provided that the current daily flow regime at Mactaquac is not changed, we recommend increased fishway operation efforts during daylight hours to increase opportunities for salmon to pass upstream. However, we also found that salmon rarely reached the fishway crowding pool during fishway visits (regardless of fishway operation status), which suggests that issues of attraction and guidance within the lower fishway should be addressed in synchrony with increased fishway operation efforts. Ultimately, our observations suggest that poor fishway attraction, guidance, and operation schedules have been key factors limiting successful upstream passage for salmon in the river and highlight the importance of evaluating fishway performance post‐construction.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".