Estimates of biological reference points for the Canadian-origin Yukon River mainstem Chinook Salmon (Oncorhynchus tshawytscha) stock aggregate
Bibliographic record
Abstract
The Yukon River Basin is one of the largest salmon producing river basins in the world and Chinook salmon (Oncorhynchus tshawytscha) from the river have historically supported commercial, subsistence, and First Nations fisheries in both Alaska and Canada. The Yukon River Chapter of the Pacific Salmon Treaty specifies a spawning escapement goal for Canadian-Origin Mainstem Yukon River Chinook salmon which has been revised over time and considered interim in nature until a comprehensive review and analysis of available data could be completed. To inform a biologically based aggregate escapement goal we developed a semi integrated state-space run reconstruction and spawner-recruitment model fit to data (1981-2019) from various assessment projects that estimate mainstem passage, harvests, tributary escapements, stock-proportions, and age-composition, under a single Bayesian estimation framework. We found that the Canadian origin Yukon River Chinook salmon stock aggregate is moderately productive. Equilibrium stock size (SEQ) was estimated to be 110,601 (95% CRI: 81,708-234,252, the spawner abundance expected to maximize long-term sustainable yield (SMSY ) was estimated to be 43,125 (29,874- 93,070) and the spawner abundance expected to maximize recruitment (SMSR) was estimated to be 70,447 (41,094-186,200). Female Chinook salmon age at maturity, and to a lesser extent the proportion of females in the spawning population, has declined over time. We adapted the integrated state-space run reconstruction and spawner-recruitment model to account for these demographic changes and found that the spawner abundance expected to maximize yield or recruitment was estimated to be on average 13% and 19% greater, respectively, in recent years than in our baseline analysis that did not take demographic changes in escapement into consideration. We outline key considerations when developing an escapement goal based on the information we provide and conclude with recommendations for future work. These include a more comprehensive consideration of the consequences of demographic change in the spawning stock and explicit consideration of trade-offs between the harvest rates, and escapement goals, predicted to maximize aggregate yield (or recruitment) and risk to individual weak (less productive) populations within the Canada stock aggregate. We also recommend undertaking a Management Strategy Evaluation that quantifies trade-offs among a broad range of objectives and evaluates the ability of alternative management strategies to meet them as part of a collaborative process with fishery participants, Traditional Knowledge holders, and resource managers.
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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 | 0.003 | 0.007 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| 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".