Size at maturity and fecundity of female American lobsters, <i>Homarus americanus</i> H. Milne Edwards, 1837 (Decapoda: Astacidea: Nephropidae), in the southern Gulf of St. Lawrence, Canada
Bibliographic record
Abstract
Abstract Accurate measurements of size at maturity and fecundity of American lobster (Homarus americanus H. Milne Edwards 1837) are necessary for estimating spawning biomass and egg production during stock assessments. A standardized methodology to determine maturity will enable comparisons between regions and over time. We describe an integrated, stepwise classification scheme based on physiological criteria to establish the size at maturity and spawning status of females. The size at which 50% of females reach the onset of maturity (SOM50) varied from 69–77 mm carapace length in the southern Gulf of St. Lawrence (sGSL); and no temporal trend was observed. Most females extruded eggs on a two-year cycle, alternating with molting; however, up to 15% of females with well-developed ovaries (i.e. ready to spawn) were in premolt (molt stages D1−D3), indicative of an alternate reproductive cycle (i.e. molting and spawning the same year). Fecundity curves were calculated for Caraquet/Malpeque (combined) and Cheticamp sites in the sGSL. Approximately 10% of berried females had reduced egg clutches (with only 38%–49% the number of eggs of full clutches). Sperm limitation was not considered a likely mechanism as the sex ratio of sexually mature lobsters was strongly male biased and spermatophores were even found in a proportion of immature females. As an alternative mechanism, we propose that a portion of females that molt and extrude eggs the same year undergo ovarian maturation prior to molting. The number of eggs produced by these females is consequently more a function of their premolt rather than current size, thus partially explaining the presence and sizes of reduced egg clutches. Further research is needed to better understand the endocrine control mechanisms of premolt females that are committed egg extrusion. Egg production analyses need to account for both the presence of reduced egg clutches and the inter-annual variability in their frequency.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".