| Summary: | The WKMSREGH met in Vigo 28th November–1st December 2011. The meeting was chaired by Fran Saborido-Rey, Spain, and Agnes Gundersen, Norway. The mandate of the group was to agree on a common maturity scale for Redfish (Sebastes mentella and S. marinus) and Greenland halibut across laboratories and propose optimal sampling strate-gies. These deep-water species are both particular; the redfish being viviparous and the Greenland halibut showing sexual dimorphism and a complex oocyte development. In addition, both show geographical variability in their life cycle. In order to address these issues the WK compared existing maturity scales for both spe-cies for the countries present in the meeting (Canada, Germany, Iceland, Norway, Russia and Spain) and produced common and standardized scales that are compatible with previous national scales. The new macroscopic scales were calibrated microscopically and reflect the peculiarities of the reproductive cycle; in order to achieve this, fresh samples, fixed samples as well as histology samples were examined and blind tests were made. For redfish, a first major issue raised in relation with the fact that in many areas the red-fish species are not distinguished, and it is known that redfish species show different ma-turity ogives. In these situations the estimation of maturity ogive is useless, at least estimating at regular basis. It is recommended to estimate the ogive in the species com-plex once every few years to be used in the assessment. Nevertheless, it is highly recommended that more effort should be allocated to a proper species identification at least during the research surveys. A scale of 6 stages was finally adopted in redfish females. This includes: 1. immature, 2. maturing, 3. Mature/fertilized, 4. embryogenesis-parturition, 5. regression-regenerating. However, skip spawning is well documented to happen in redfish during early-mid vitellogenesis and to account this feature stage 2 was divided in two stages to be used only in the period right before ovulation, ...
|
|---|