Acoustic and Trawl Surveys to Locate Eulachon Aggregations in the Lower Fraser River, British Columbia
Bibliographic record
Abstract
Abstract Coordinated acoustic and trawl surveys were performed to locate aggregations of adult eulachon Thaleichthys pacificus in the lower Fraser River, British Columbia, during spring 2001 and 2002. Aggregations were encountered in one portion of the study area in both years. They contained mature, spawning, and spent eulachon of both sexes, of which over 80% were spent males. These groups were 880–2,000 m long and averaged 117–140 m wide. Within them, mean fish density was 0.27–0.29 fish/m3 and species composition was 87–99% eulachon. They occurred in 6–8.5 m of water over substrate that was mainly sand with a small fraction of pea gravel. We did not determine whether these eulachon spawned in that area or had congregated there for another purpose, such as holding or migration. Other species occasionally encountered in appreciable numbers were juvenile pink salmon Oncorhynchus gorbuscha and chum salmon O. keta. Mean in situ target strengths of eulachon were −53.3 dB at 123 kHz and −50.3 dB at 208 kHz. Coordinated acoustics and trawling were effective for locating eulachon aggregations at low to moderate flows (river discharge of 3,200 m3/s or less), but were hampered by entrained debris during higher flows of spring runoff. Under suitable river conditions, the high resolution and rapid spatial coverage of this technique are apt for habitat preference studies and point source environmental assessments in large, turbid rivers.
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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 | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".