Sex Determination, Differentiation, and Control in Atlantic Halibut and Pacific Halibut
Bibliographic record
Abstract
This chapter summarizes current knowledge of sex determination and sexual differentiation in the two largest species of flatfish, the Atlantic and Pacific halibut, and best approaches for producing all-female populations of Atlantic halibut. Atlantic halibut clearly have a female-homogametic sex-determining system, whereas Pacific halibut appear to have a female-heterogametic system, although the evidence is not definitive. There is no information on the timing of sexual differentiation in Pacific halibut, and no attempts have been made to control sex in this species. Atlantic halibut are gonochoristic, and differentiation of the ovaries precedes that of the testes. Primordial gonads are present in larvae by 20 mm fork length (FL), and ovarian differentiation is apparent by 38 mm FL. This corresponds to the interval from the start of exogenous feeding as post-larvae, to the completion of metamorphosis as juveniles. Ovarian cytochrome P450 aromatase appears to play a role in ovarian differentiation in Atlantic halibut, based on patterns of cyp19a transcription, and the small, non-coding microRNA miR-202-3p may also play a role in regulating sexual differentiation. Fully functional “neomale” (masculinized genetic female) Atlantic halibut can be produced by feeding juveniles a diet containing synthetic androgen or aromatase inhibitor for approximately six weeks, beginning around the end of metamorphosis, and such neomales have been used to produce all-female populations for commercial aquaculture, to take advantage of the faster growth of females compared to males. Attempts to alter sex ratios in Atlantic halibut by manipulating rearing temperature during sexual differentiation have not been successful.
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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".