Report of the Workshop on Sexual Maturity Staging of sole, plaice, dab and flounder (WKMSSPDF)

DWhen assigning maturity stages to fish, it is important to have an understanding of the biology of the fish and its reproductive cycle in the sampling area. This helps to distinguish the transitions between the different stages.

WKMSSPDF 2010 proposed to adopt the 6 point scale as proposed by the gadoid workshop WKMSCWHS 2007 (ICES, 2008). From wide ranging discussions it has be-come evident that outside the spawning period it is not reliably possible to distin-guish between what is described as a resting stage 5 and a re-maturing stage 2 (histological pictures have given credence to this). To this end it is recommended for flatfish, stage 5 should only be used during the proposed sampling period (see ‘Op-timal sampling time’) and only to describe a skipped spawning fish.

It is recommended that institutes carry out in-house workshops on the reproductive biology of the fish and maturity staging, also as a follow-up of WKMSSPDF2010 to introduce the new common scale. An important aspect of the introduction of the new common scale is to take care that all institutes will be able to transpose their own scale into the common scale. This will give the flexibility for the institutes sometimes to keep their own scale but to internationalise their data in an easy way.escription not yet available.