Fish community changes in Shoal Lake, Canada, following the overexploitation of a top predator
Bibliographic record
Abstract
Overexploitation of a single target species often results in fish community changes. Commercial and recreational overexploitation of walleye (Sander vitreus) in Shoal Lake, Ontario, in the early 1980s resulted in a ban on walleye fishing. In this study, we summarize potential changes in the catch-per-unit-effort of large-bodied fishes (abundance and biomass in gill nets) and small-bodied fishes (abundance in shoreline seines) for most years in the period 1979–2001. Through our analysis of gill net data, we found that the collapse of walleye was followed by increases in the abundance and biomass of yellow perch (Perca flavescens), cisco (Coregous artedi), and white sucker (Catostomus commersoni). Lake whitefish (Coregonus clupeaformis) also increased following the collapse, but this pattern was confounded by reduction in the lake whitefish commercial harvest. We found no evidence that the collapse of walleye benefited potential competitors (e.g. northern pike, Esox lucius). The collapse also resulted in semi-annual alternations between minnow (Pimaphales spp.) and a combination of yellow perch and shiners (Notropis spp.). Overall, our results are consistent with the general literature showing that the overexploitation of a top predator affects the broader community and with the walleye literature showing that these community shifts tend to reflect a top-down, trophic cascade that stems more from predator–prey relationships than from competitive relationships. Our case study provides important insight into the structure and function of aquatic food webs and the trophic ecology of top predators.
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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 | 0.000 | 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 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".