Critical Thermal Maxima of Two Geographic Strains of Channel and Hybrid Catfish
Bibliographic record
Abstract
Abstract Critical thermal maxima have been used extensively to provide physiologically and ecologically valuable reference points that identify early signs of thermal stress. In catfish pond culture, daily temperature maxima up to 36°C and daily fluctuations of as much as 6°C are observed. These extreme conditions will probably be exacerbated by the effects of global climate change. Channel Catfish Ictalurus punctatus have a broad natural distribution from southern Canada to northern Mexico. If regional genetic differences could cause strains with a southern distribution to have greater thermal tolerance than strains with a northern distribution, and consequently a greater critical thermal maximum, then hybrid catfish (Channel Catfish × Blue Catfish I. furcatus) strains might be expected to have greater critical thermal maxima than their respective Channel Catfish strains because Blue Catfish have a more southern range of distribution. To examine this, we quantified differences of acute thermal tolerance in two geographically distinct strains of Channel Catfish and their hybrid crosses with an industry standard strain of Blue Catfish. The catfish were subjected to water temperature increases of 2.0 ± 0.1°C · h−1 until they lost equilibrium. Standard length, which ranged from 162 to 320 mm, had a significant effect on survival, survival being greater in larger fish. The critical thermal maximum ranged from 38.6°C to 40.3°C. Southern Channel Catfish tolerated higher temperatures than northern Channel Catfish did, and both strains of Channel Catfish tolerated higher temperatures than their hybrid catfish strains did. This study indicates that geographically distinct catfish strains differ in acute thermal tolerance and suggests heritability for this trait, as evidenced by similar responses in Channel Catfish and their corresponding hybrid crosses with Blue Catfish.
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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 | 0.000 | 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".