Death Of A Salmon: An Investigation Of The Processes Affecting Survival And Migration Of Juvenile Yearling Chinook Salmon (Oncorhynchus Tshawytscha) In The Lower Columbia River And Ocean Plume
Bibliographic record
Abstract
From 2008 to 2011, migrating acoustic-tagged juvenile yearling Chinook salmon smolts (Oncorhynchus tshawytscha) were detected on receivers deployed across the Columbia River and continental shelf at Cascade Head (Oregon), Willapa Bay (Washington), and Vancouver Island (British Columbia). The telemetry data were used to estimate survival and record migration parameters. These were evaluated against oceanographic and freshwater hydrologic variables in statistical and individual-based models. Plume survival was found to be variable, but daily survival rates were more constant and survival was effectively modeled as exponential decay. Correlates of early marine survival that do not have direct effects may act on plume survival by controlling the period of exposure to plume predation. In 2011, half of smolts released were exposed to total dissolved gas levels (TDG) above 120%, the water quality limit for TDG below Columbia River dams. This exposure appears to have negatively affected daily survival rates in the lower river and plume, and has important implications for a proposal to increase the TDG limit to 125% to support spring fish passage. Finally, consistent with the critical size, critical period hypothesis of salmon production, it appears that smolts select habitat to maximize their growth as they migrate north through the plume, rather than selectively using local currents to speed their passage. These findings shed new light on perennial questions in salmon early marine ecology. They lay the groundwork for future research aimed at understanding the effects of changing oceanography and freshwater hydrology on salmon migration and survival.
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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) | 0.000 | 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".