A unified scale for female reproductive stages in the Norway lobster (Nephrops norvegicus): Evidence from macroscopic and microscopic characterization

Carola Becker*, Eoghan M. Cunningham, Jaimie T.A. Dick, Lawrence E. Eagling, Julia D. Sigwart

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)
289 Downloads (Pure)


Knowledge of the reproductive cycle in exploited species is important for a sustainable management of fisheries. Standardized scales to assess maturity stages are a fundamental tool to understand the demographic composition of exploited populations. Staging scales for female Norway lobster, Nephrops norvegicus, have been subject to a series of changes, and multiple inconsistent scales are in use in different fisheries regions. A unified, evidence-based scale has not previously been established. We reviewed previous staging scales for the female ovary maturation and propose a revised scale based on the correlation between macroscopic and microscopic ovary characteristics. To provide better-informed tools for future stock assessment, female stages were characterized through external observation on ovary color and size, and the progress of vitellogenesis. This study clarifies several biological phases that were conflated in previous scales. First, we demonstrate how to distinguish between immature ovaries in juvenile females versus the earliest ovary maturation stage in adults. Second, the new scale differentiates between “mottled” ovaries seen in two separate biological stages: the spent ovaries that undergo partial resorption in berried females, versus ovaries of females which failed to spawn and undergo full resorption. To ensure consistent application, colors are assessed relative to international standards (RAL/Pantone). This new, practical staging scheme clarifies the correlation between microscopic characteristics and macroscopically observable details in ovary maturation. Adoption of this unified staging scale will improve maturity analyses, help to identify stocks with potentially reduced reproductive capacity, and facilitate broad-scale comparisons.

Original languageEnglish
Pages (from-to)1700-1715
Number of pages16
JournalJournal of morphology
Issue number12
Early online date31 Oct 2018
Publication statusPublished - 01 Dec 2018


  • color assessment
  • female reproductive cycle
  • oogenesis
  • ovary maturation
  • resorption

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Developmental Biology


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