Determinate Versus Indeterminate Fecundity in American Shad, an Anadromous Clupeid
Bibliographic record
Abstract
Abstract Historical fecundity estimates of American Shad Alosa sapidissima used a determinate method that estimated annual fecundity as the standing stock of oocytes at a single point of time prior to spawning. Such fecundity estimates have been (1) reported for populations from the Canadian Maritimes to Florida, (2) applied to hypothesis tests of life history evolution, and (3) used in demographic models to advise management policy. However, American Shad have asynchronous development of yolked oocyte clutches, which suggests that new oocytes could arise after spawning commences, biasing the results of a determinate fecundity method downward. If so, annual fecundity should be a product of batch size and the number of batches—an indeterminate fecundity method. We investigated oocyte recruitment, atresia, and spawning intervals using gonad histology of females from the Mattaponi River, Virginia. Batch size (i.e., the number of hydrated oocytes prior to a spawning event) was estimated using a gravimetric method. Spawning duration was obtained from an independent acoustic tagging study. A size hiatus between primary and secondary oocytes was only evident in some individuals during spawning, so we conclude that an indeterminate fecundity method is necessary for this population of American Shad. Atresia was evident during spawning but was low at the end of the 2002 spawning season. Females spawned every 2.2–2.9 d, releasing 11–17 batches per season. Batch fecundity (range: 12,700–81,400) was 23% higher for repeat versus virgin spawners. A bootstrapped estimate of potential annual fecundity for a virgin female—as calculated with an indeterminate fecundity method—was 478,000–544,000 eggs (95% confidence interval), about double the previous (determinate) estimates from this river system (260,000 and 288,000). Until more comparisons are done with other populations, we urge caution in using the many published determinate fecundity estimates of American Shad and other Alosa species.
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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 | 0.000 | 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".