Evaluating the potential for grey seal predation to explain elevated natural mortality in three fish species in the southern Gulf of St. Lawrence
Bibliographic record
Abstract
Despite 2 decades of very low fishing levels, numerous NW Atlantic demersal fish stocks have failed to recover from collapsed states or are presently collapsing. In the southern Gulf of St. Lawrence, adult natural mortality (M ) appears to be the demographic rate that most limits population productivity in at least 3 species: Atlantic cod Gadus morhua, white hake Urophycis tenuis and winter skate Leucoraja ocellata. The causes of elevated M are not well understood, though there is indirect evidence consistent with an effect of predation by grey seals Halichoerus grypus. However, direct evidence is lacking due to uncertainty in the seal diet. Consequently, Monte Carlo simulations were undertaken using data on the spatial overlap between the seals and the fishes and a seal food-consumption model, to estimate the plausibility that different seal-diet compositions could explain observed M levels. Under the simulation assumptions, we find that predation could explain up to 20 to 50% of M in adult white hake and cod even if these species comprise a small percentage of grey seal diets (< 25%). If seals consume some of these fish only partially, by selectively feeding on soft tissues, a predation effect becomes more plausible. Predation can also plausibly explain the observed elevated M in adult winter skate, even if they comprise a negligible (< 0.1%) percentage of the grey seal diet. Though the simulations deal with the factors that shape the potential for predation, a greater understanding of prey selection is required to conclude whether grey seals are actually adversely impacting these fish populations.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".