Diet composition of redfish (Sebastes sp.) during periods of population collapse and massive resurgence in the Gulf of St. Lawrence
Bibliographic record
Abstract
Redfish ( Sebastes mentella and S. fasciatus ) are back at spectacular record high levels in the Gulf of St. Lawrence (GSL) and the effects of this massive resurgence on other components of the food web remain largely unknown. To better understand the trophic implications of the surging redfish biomass within the GSL ecosystem, 3,690 stomachs containing food were collected during two periods: one characterised by low redfish abundance (1993–1999) and the other during a period of record abundance (2015–2019). Taxonomical analysis of stomach contents from individuals of different sizes from three subareas of the GSL was carried out to determine diet composition during both periods. Zooplankton represented the main prey category for small redfish (< 20 cm), which was driven by a predation on amphipods, mostly Themisto sp. in North-East Gulf, in the 1990s and on copepods of the genus Calanus in the deep channels and euphausiids in North-West Gulf in the 2010s. Themisto sp. still dominated the diet of medium (20–30 cm) redfish in the 1990s while the copepods were predominant during the 2010s. Shrimp consumption increased with redfish size and two species were particularly important in large redfish diet (≥ 30 cm) during both periods: pink glass shrimp ( Pasiphaea multidentata ), mostly in the Laurentian Channel and northern shrimp ( Pandalus borealis ), especially in North-East Gulf. Redfish predation on shrimp represents a major concern for the dynamics of the northern shrimp which supports a valuable fishery in the GSL but has been declining in abundance since several years. Piscivory was observed in large redfish diet, with capelin ( Mallotus villosus ) being the major fish prey in the 1990s and redfish (cannibalism) in the 2010s, suggesting density-dependent control at high density of small redfish. By presenting a detailed overview into the redfish diet composition and its temporal variability, the present study offers a first look into the possible future trophic impacts of a resurging groundfish in the GSL ecosystem.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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 teacher head, 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".