Movement patterns of the tropical shad hilsa (<i>Tenualosa ilisha</i>) inferred from transects of <sup>87</sup>Sr/<sup>86</sup>Sr isotope ratios in their otoliths
Bibliographic record
Abstract
We examine 87Sr/86Sr isotope ratios in transects across the otoliths of the diadromous tropical shad hilsa, Tenualosa toli, to assess the extent of movement of fish within the large Meghna (Ganges) River system and adjacent coastal waters. Hilsa collected from marine, estuarine, and freshwater habitats were born in all main rivers in Bangladesh. All fish moved widely, entering water of marine 87Sr/86Sr isotope ratio by 1 year of age. Most returned to fresh water after they reached sexual maturity, but not necessarily to their natal region. Comparison of the 87Sr/86Sr isotope and Sr/Ca ratios of hilsa showed that in the Meghna River, 87Sr/86Sr isotope ratios can only distinguish fish from waters when the salinity was less than 5. Sr/Ca ratios were more useful for interpreting fish movements at higher salinities. To assess whether whole-otolith 87Sr/86Sr isotope ratios reflected the ratios of the water of natal origin, we compared the 87Sr/86Sr ratios of otolith cores with the mean 87Sr/86Sr isotope ratio of the whole transect. We found major differences between the two measurements, suggesting that 87Sr/86Sr isotope ratios from whole-otolith assays may not accurately reflect the natal origin of the fish.
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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 | 0.001 | 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".