Effect of Photoperiod Advancement of Atlantic Cod Spawning on Egg Size and Biochemistry
Bibliographic record
Abstract
Abstract We report on the proximate composition, lipid class, and fatty acid content of fertilized eggs during the course of one spawning season from two broodstocks of Atlantic cod Gadus morhua: One group was maintained under ambient photoperiod (PP), whereas for the second group the natural photoperiod cycle was compressed by approximately 4 months by PP advancement from ambient. We tested the hypothesis that PP compression, which reduces the time between successive spawning seasons and therefore reduces the time available for vitellogenesis and maturation, might also impair nutrient transfer to the eggs, causing reduced egg quality as measured by biochemical indices. Advanced PP eggs were significantly larger than ambient control eggs (absolute mean values for dry weight = 109.2 and 97.9 μg, respectively). Advanced PP eggs also had significantly greater mean total protein (60.0 versus 49.4 μg), mean total lipid (15.1 versus 9.7 μg), and greater mean values for several major lipid classes (hydrocarbons, triacylglycerols, sterols, diacylglycerols, and phospholipids) than ambient controls. Proportionally (percent of dry weight), mean total lipid, ash, triacylglycerols, total saturated fatty acids, and total polyunsaturated fatty acids, including total ω-3, total ω-6, docosahexaenoic acid, eicosapentaenoic acid, and arachidonic acid, were all significantly greater in eggs of the advanced PP group than in ambient controls. The latter contained proportionally more monounsaturated fatty acids. Mean dry weight of eggs declined over time from onset of first spawning in the ambient PP group but not in the advanced PP group, and none of the measured biochemical indices varied significantly over time from onset of first spawning in either PP group. We conclude that with the PP advancement technique used here, compression of time between successive spawnings by up to 4 months in Atlantic cod does not negatively affect biochemical indices of egg quality associated with normal development or survival performance.
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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".