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Workshop on Elasmobranchs maturity (WKSEL3).pdf (3.95 MB)

Workshop on Elasmobranchs maturity (WKSEL3; outputs from 2018 meeting)

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posted on 2020-10-06, 00:00 authored by ICESICES

The WKMSEL3 meeting aimed to update and validate the international maturity stages for elasmobranchsspecies (viviparous and oviparous) and prepare conversion tables for the maturityscales used by the institutes to the international scale. The update was carried out on the base ofthe results presented from the participants including hystological validation.

Some changes were made on the criteria and description of each maturity stages of the WKMSEL2scale, considering the expertise and experiences from both Atlantic and Mediterranean species.Therefore particular attention was devoted to have clear elements useful to discern juvenilesand adults stages. Indeed, this item has a high impact on the Stock Spawning Biomass quantificationand, more in general, on the stock assessment for the elasmobranchs species.

For oviparous species, in the male maturity scale, the specification of thorns presence was introducedas a characteristic that can help to distinguish some maturity stages from each other (Stage1 vs Stage 2; Stage 2 vs Stage 3a). Moreover, lobuli segmentation and seminal vesicles weredeeply specified in the stage descriptions. Furthermore, the name of Stage 4 was changed from REGRESSING to SPENT. This term was considered as more appropriate to include all phases(post-spawning, rest and regenerating) described in this stage.

In oviparous, female maturity scale, the uteri appearance and oviducal glands in some maturitystages was taking into account to help the distinction of maturity stages from each other.

In the viviparous females, the description of the ovary and oviducal gland for the Stage 4a, 4b,4c, 5 and 6 was added to maturity scale. Moreover it was inserted a Stage 7 (LATE REGENERATING) in which the atretic follicles are unlikely because they are developing and the Stage 6was renamed (EARLY REGENERATING).

Two staging exercises were carried out, one using a shark viviparous species (Etmopterus spinax)and another one using a shark oviparous species (Galeus melastomus). Generally, participants feltthat G. melastomus was easier to stage than E. spinax. Indeed, the viviparous scale is more complicatedmostly for the females (9 stages). Moreover, in males and females, there was a confusionalso in the sex determination for the juveniles of this species, since the claspers in the stage 1 arenot easily visible determining a source of errors. Regarding the maturity stage for G. melastomus,the agreement was 71.8%, while for E. spinax, the agreement was 68.5%.

The macroscopic maturity stages were validated with the histological analysis in G. melastomus(oviparous) and E. spinax (viviparous) for both sexes. The microscopical validation was donetaking into account the criteria fixed in WKMATHIS (ICES, 2018).

The picture references collection was improved from the previous workshop (WKMSEL2) by thephotos of the participants discussed in plenary. The Atlas was amplified in term of case studies (Galeus atlanticus, Prionace glauca, Urolophus spp, Squalus acanthias, S. blainville) and macroscopicfeatures suitable for the determination of each maturity stage.

For all scales, conversion tables are presented to the international agreed scale.

It was recommended that the next meeting should be in 3 years. 

It was also recommended thatthe national institutes should be strongly encouraged to put effort into making pictures, and should find time and money to do so. Successful maturity staging workshops cannot be carriedout without these pictures. 

Moreover, the establishment of a Working Group including also the ageing analysis was encouraged from all participants.

History

Published under the auspices of the following ICES Steering Group or Committee

  • EOSG

Published under the auspices of the following ICES Expert Group or Strategic Initiative

WKSEL

Series

ICES Scientific Reports

Volume

2

Issue

90

Contributors (Editors)

Pierluigi Carbonara; Maria Cristina Follesa

Contributors (Authors)

Aikaterini Anastasopoulou; Andrea Bellodi; Pierluigi Carbonara; Danila Cuccu; Marilena Donnaloia; Maria Cristina Follesa; Martina Francesca Marongiu; Marlén Knutsen Myrlund; Cristina Porcu; Sámar Saber; Francisca Salmeron; Marina Sartini; Letizia Sion; Fabian Trinnie

ISSN

2618-1371

Recommended citation

ICES. 2020. Workshop on Elasmobranchs maturity (WKSEL3; outputs from 2018 meeting). ICES Scientific Reports. 2:90. 103 pp. http://doi.org/10.17895/ices.pub.7501

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