Multifaceted Environmental Enrichment in Industrial Fish Hatcheries: The Influence of Enriched Rearing on the in-situ Behaviour and Post-stocking Success of Juvenile Atlantic Salmon (Salmo salar)
Bibliographic record
Abstract
Hatchery fish reared and stocked to sustain or restore wild populations often perform poorly in novel environments compared to their wild counterparts. To combat maladaptive hatchery-acquired traits environmental enrichment is an emerging tool used to provide ‘life skills training’ to hatchery fish prior to release. Through the application of simple yet multifaceted enrichment protocols in an industrial fish hatchery, this thesis aimed to demonstrate how enrichment could be applied to improve the ecological viability of stocked fish. At a provincially-run fish hatchery, a subgroup of juvenile Atlantic salmon (Salmo salar) were subject to 10 weeks of environmental enrichment (live food, live predators, in-tank structure) and their performance metrics were assessed and compared to non-enriched fish. In-situ behavioral response data revealed that enriched fish had significantly (57%) better foraging abilities throughout all behavioural trials assessed. Non-enriched fish exposed to a predatory chemical stimulus (Rainbow trout, Oncorhynchus mykiss) showed significantly better antipredator tactics supported by reductions in foraging behaviours, but not by reductions in movement behaviours. Post-stocking field data concluded that passive integrated transponder (PIT) tagged salmon (n = 2,039) stocked into Duffins Creek (Ajax, ON) had 1.6% higher in-stream detection rates and significantly faster movement speeds (13%) within the first 5rkm when compared to non-enriched fish. Additionally, acoustically tagged salmon (n = 60) demonstrated that the detection proportion of enriched and non-enriched fish was similar throughout the first 5rkm of the creek, but enriched fish had ~10% higher detection proportions and 32% faster movement speeds onward to Lake Ontario (20rkm). The information presented in this thesis demonstrates the significant benefits of environmental enrichment and has implications for fisheries management and restoration efforts.
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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 | 0.000 | 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 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".