Evidence for spawning habitat preference of eulachon, an endangered anadromous smelt in the Fraser River, British Columbia
Bibliographic record
Abstract
The anadromous smelt, eulachon Thaleichthys pacificus , population was historically abundant in the Fraser River. Extensive anthropogenic impacts in the river have induced both short-term and long-term changes to the hydraulic and sediment transport characteristics of the river channel, potentially changing the availability of eulachon spawning habitat. Despite these extensive anthropogenic impacts to the riverbed, there is limited understanding of spawning habitat utilization by eulachon in the river. Our purpose was to characterize spawning habitat preference in Fraser River. Available habitat was characterized in 3 locations using a combination of multibeam sonar to describe bathymetry, side scan sonar to describe surficial bedforms, and sediment sampling to describe substrate composition. Artificial spawning substrate were deployed in available habitats to measure egg deposition rate throughout the migration period. Results show that of the 5 habitat types we examined, smooth bedform features composed of coarse sands and medium gravels were the most productive habitat type selected for spawning based on egg deposition. Un-eyed egg deposition followed a unimodal distribution pattern throughout the adult migration period. Drifting eyed egg deposition increased towards the end of the adult migration period, indicating downstream drift of eggs spawned further upstream. This study highlights the value of incorporating surficial bedform features and substrate composition to characterize and assess spawning habitat selection and preference and demonstrates the importance of incorporating egg developmental stage to distinguish spawning habitat use. River management decisions will need to consider both surficial bedforms and substrate composition when assessing and protecting critical spawning habitat.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| 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".