Physiological correlates of coastal arrival and river entry timing in late summer Fraser River sockeye salmon (Oncorhynchus nerka)
Bibliographic record
Abstract
Animal migrations typically occur within a predictable time frame and sequence, but little is known about the triggers that initiate migration, despite their importance in animal ecology and for resource management. The migration of adult sockeye salmon (Oncorhynchus nerka) in the Fraser River, British Columbia, Canada, is an excellent model to study such triggers because for nearly a decade a segment of the late summer stocks has been proceeding into the river as much as 6 weeks earlier than the historic norm. In this study, late-run sockeye salmon (N = 146) were intercepted about 215 km from the mouth of the Fraser River and implanted with radio transmitters. These fish were biopsied, which included drawing blood from the caudal vessels, removing some gill filament tips, and quantifying energetic status using a microwave energy meter. Fish that entered the river without delaying in the estuary were in a more advanced state of reproductive maturation, as evidenced by hormone and energy levels. Indicators of osmoregulatory preparedness (i.e., plasma ions and gill Na-super-+/K-super-+-ATPase activity) provided little insight into migration timing aside from greater variation in Na-super-+/K-super-+-ATPase activity in fish that entered early relative to those that held in the ocean. Given the dissimilar reproductive hormone profiles for early arrival into the estuary and early entry into the Fraser River, it appears that only a subset of the population are early migrants and triggers for early migration may be related to a relatively advanced reproductive development and higher energetic status. These findings provide the first assessment of the physiological correlates of migration timing and provide a mechanistic understanding of the proximate factors associated with abnormal migration timing in late-run sockeye salmon. Copyright 2008, Oxford University Press.
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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 | 0.000 |
| 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".