Where do you come from, where do you go: early life stage drift and migrations of cod inferred from otolith microchemistry and genetic population assignment
Bibliographic record
Abstract
This study investigates stock mixing of genetically distinct Atlantic cod (Gadus morhua) stocks in the Kattegat, an area geographically located between the North Sea and the Baltic Sea, by combining genetic population identification with habitat assignments from hatch to capture from otolith microchemistry. Cod captured in Kattegat were genetically assigned to either the North Sea or the endemic Kattegat population. Otolith chemical fingerprints differed significantly between populations during the larval and pelagic juvenile stage with higher strontium and lower barium and manganese concentrations in the North Sea population than the Kattegat population, indicating that North Sea cod are spawned in the North Sea or Skagerrak and drift into the Kattegat during the early life stages. Individual cod of both populations undertook frequent, but predominantly short-term, migrations to other areas than the Kattegat, with <25% of individuals remaining resident within the Kattegat throughout their life. Across seasons and age classes, the two populations were both most frequently distributed in the Kattegat (67%), with approximately 25% of both population distributed in the western Baltic Sea and less than 10% in the Skagerrak–North Sea. This study demonstrates the usefulness of this approach to infer population-specific connectivity and migration trajectories for individual fish and its potential applications in basic and applied fields of fish ecology and fisheries sciences.
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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 | 0.000 | 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".