Change in trophic structure of a shelf ecosystem in the northwest Atlantic during a period of increased fishing pressure
Bibliographic record
Abstract
Multi-species and ecosystem modelling are increasingly touted as essential approaches in the future of fisheries management. These methodologies can involve the amalgamation of data on the landings, biomass, consumption, production, and diets of many species or species groups in current time, the future and in the re-examination of the past. The Ecopath approach was used to construct two mass balance ecosystem models for the southern Labrador Shelf, Northeast Newfoundland Shelf and Grand Bank in Northwest Atlantic Fisheries Organisation (NAFO) Divisions 2J+ 3KLNO the first for the time period 1954-1956 and the second for 1968-1970. Our models increased the temporal resolution of ecosystem models developed by The Fisheries Centre at the University of British Columbia. The start (1950s) and rapid expansion (1960s) of industrial harvesting by factory freezer trawlers during these time periods resulted in massive increases in fishing effort, the total catch increased by 30%, and there was extensive spatial intensification and expansion, particularly on the Labrador Shelf. Biomass declines in adult and juvenile Atlantic cod, harp seals, and their main prey species capelin and sandlance were evident. A change in predator/prey relationships between the two time periods was expected, but not found. An increase in the biomass of some invertebrate species groups was expected, but not evident, possibly due to sparse historical data. System ratios and indicators pointed to the latter ecosystem as nearer to a state of being 'fished down', perhaps indicating the onset of the trophic shift evident in the late 1980s and 1990s.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".