Reproduction, Growth and Development in Captive Beluga (<i>Delphinapterus leucas</i>)
Bibliographic record
Abstract
Abstract Recent success propagating captive beluga has resulted from combined efforts by North American zoos and aquariums to manage disparate collections as a single population. This success has provided a tremendous opportunity to increase our understanding of beluga reproductive biology. Blood samples were collected on a weekly to biweekly basis from 23 female and 12 male beluga, ranging in age from 2–15 years, for analysis of serum progesterone (P) and testosterone (T), respectively. Peri‐parturient observational data, including food intake, duration and signs of labor, and nursing patterns were collected from 15 days prepartum to 30 days postpartum during 21 births. Total body lengths and weights were collected from 10 captive‐born beluga. For female beluga, the mean (±SD) age, body length, and weight at first conceptions were 9.1±2.8 years, 318.0±9.1 cm, and 519±84 kg. Thirty‐five luteal phases and 13 conceptions were detected from January–June, and 70% of luteal phases and 80% conceptions occurred from March–May. The mean luteal phase and total estrous cycle lengths were 30.0±6.5 days and 48.0±4.6 days, respectively. For male beluga, the mean age that males sired their first calf was 13.3±2.6 years. Compared to younger males (<8 years of age, 0.95 ng/ml), levels of T secretion in older males (>8 years of age, 5.0 ng/ml) were elevated significantly only during the interval from January–April. Highest T concentrations (6.2±4.9 ng/ml) were recorded from January–March, whereas nadir concentrations (1.1±1.0 ng/ml) were detected from August–September. The mean gestation length was 475.0±20.4 days ( n =9). For parturition, the mean time from the first appearance of fluke or rostrum to delivery, delivery to placental passage, and delivery to nursing were 4.4±2.9 hr, 7.6±1.8 hr, and 43±45 hr, respectively. All cows had decreased food intake on the day of delivery, with 44% having zero intake. Peak 24‐hr nursing activity occurred 3.9±2.7 days post‐partum. Growth (i.e., body weight and length) as a function of age were well described by the Gompertz model ( r 2 =0.91, 0.93). Based on the model, growth in body weight and length were significantly greater in males compared to females. Predicted birth weight (88.9 kg) was similar for both sexes, however, and male calves were predicted to be shorter (154.3 cm) than female calves (160.7 cm). The results provide the first descriptions of captive beluga reproductive physiology, including endocrinology, peri‐parturient behavior, growth, and reproductive maturity. This knowledge is important for helping to maintain genetically diverse, self‐sustaining populations of captive beluga whales. Zoo Biol 24:29–49, 2005. © 2005 Wiley‐Liss, Inc.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".