Risk factor studies of bacterial gill disease outbreaks in Ontario government salmonid hatcheries
Bibliographic record
Abstract
This thesis is an investigation of risk factors associated with bacterial gill disease (BGD) outbreaks in early-rearing salmonids in Ontario government (Ontario Ministry of Natural Resources (OMNR) and Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA)) fish culture stations. Two retrospective studies were conducted utilizing (i) centralized OMNR records (1994-2001), and (ii) on-site records (1999) from three OMNR hatcheries. Subsequently, a 14-month (July 2002--August 2003) prospective matched nested case-control study was carried out to identify factors associated with BGD outbreaks in five OMNR and one OMAFRA hatcheries. Using multivariable proportional hazards survival analysis, the retrospective study using centralized records revealed that the species brook trout (' Salvelinus fontinalis') and the Spring season (March--May) were significant (p<0.10) risk factors for early-rearing lot treatment for BGD. Data from three hatcheries were analyzed separately using multivariable repeated measures in the second retrospective study. Significant risk factors for BGD were (i) the species brook trout ('S. fontinalis') and lower biomass (tank-lot level); (ii) lower individual fish weights, lower water exchange rates, and higher feeding rates (tank-lot level); and (iii) early-rearing, higher biomass, and a history of BGD treatments (lot-level). Multivariable logistic regression analysis of the prospective case-control data indicated tank-lots with confirmed BGD outbreaks were significantly more likely to have lower fish numbers, lower individual fish weights, higher mortality levels and higher feeding rates during the week preceding BGD outbreaks than were asymptomatic control tanks matched on hatchery, species, and time. The predictive (as opposed to causal) nature of these identified risk factors indicate the need for further research to understand the relationships between these factors and BGD.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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".