Fish harvest and replacement of top piscivorous predators in aquatic food webs: implications for restoration and fisheries management
Bibliographic record
Abstract
The potential for walleye (<i>Sander vitreus</i>) restoration at Lac la Biche, Alberta, Canada is a social-ecological question that requires understanding of changes to ecosystem integrity and historical fidelity resulting from disturbance. This study explored variability in fisheries-induced disturbance across time, examined the effects of disturbance on ecosystem structure and functioning, characterized the system during different eras from pre-European settlement to the present, and assessed walleye restoration potential based on conceptual models describing the system response to disturbance. An anthropological assessment of historical harvest was conducted (1800 to 1900) to estimate the magnitude of subsistence lake whitefish (<i>Coregonus clupeaformis</i>) harvest during rapid settlement of the Lac la Biche area. The results were compared to more recent harvest estimates (1900 to 2009) reflecting combined commercial, subsistence and recreational harvest, to describe the relative variability in the magnitude of fishing disturbances during the 200 years preceding the current restoration project. Ecosystem models for 1800 and 1900 were used to examine how historical fisheries affected the structure, functioning, and resilience of the system, and to assess if targeting system conditions in 1900 would satisfy the restoration goal of a walleye-dominated ecosystem. Results suggest little change in ecosystem structure and function between 1800 and 1900, though the trend in the analyses is towards declining system maturity and resilience. Parameters and state variables used as model inputs provide plausible values for guiding the restoration program. Potential success of the walleye restoration program was addressed using a series of models representing four eras (1800, 1900, 1965, 2005) to test the for multiple ecosystem states, specifically a walleye-dominated equilibrium and a double-crested cormorant (<i>Phalacrocorax auritus</i>) dominated equilibrium. Identification of alternate stable attractors would influence the predictability of system recovery following a disturbance. Results from over 900 model simulations suggest both walleye and cormorant attractors existed in historical (1800, 1900) models but a single cormorant-dominated equilibrium is present in contemporary models (1965, 2005). Differential size-selective foraging of walleye and cormorants on yellow perch (Perca flavescens) provides a negative feedback stabilizing each state. Recovery of a walleye population seems possible but restoration of a walleye-dominated ecosystem was not predicted.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 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 | 0.000 | 0.001 |
| 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".