Release strategies affect the freshwater residence and survival of hatchery-reared juvenile Chinook Salmon
Bibliographic record
Abstract
ABSTRACT Objective This study investigated the effects of release size, location, and timing on freshwater residence and survival probability of hatchery-reared Chinook Salmon Oncorhynchus tshawytscha in the Toquaht River, British Columbia. Methods A total of 4,845 passive integrated transponder (PIT)-tagged juvenile Chinook Salmon were released at three locations on the river (lower river [below lake], lake, and upper river [above lake]) and on three dates between May 23 and June 19, 2021. Freshwater residence and survival were assessed using a PIT tag array located near the river mouth. The detection data were analyzed using an integrated model of freshwater residence and capture–recapture using Bayesian inference. This approach allowed us to account for the uncertainty in environmental conditions experienced by migrating fish that went undetected. Results The median freshwater residence of the PIT-tagged fish was 13.8 d and was longer for fish released in the lake or upper-river locations and for juveniles released earlier in the study period. The median freshwater survival of the PIT-tagged fish was 0.35, and it was greater for fish released in the lake or upper river and for release dates later in study period. Both freshwater residence time and survival decreased with increasing fish size at release. Conclusion The results highlight that hatchery release strategies can substantially influence freshwater residence and survival. Current release strategies should be experimentally evaluated on a program-by-program basis and reconsidered depending on findings and hatchery objectives.
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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 | 0.000 | 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) | 0.001 | 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".