In order to meet its objectives, WKMSGAD's main tasks are:
To develop common standard maturity scales with historically validated criteria for the aforementioned fish species
To finalize the illustrated and validated manuals that were previously drafted during the WKMSCWHS workshop in 2007
Maturity scales often vary on a national level due to different countries utilizing different criteria. The national scales needs to be successively converted into the international conventionally approved staging system before reporting to ICES. At present the majority of maturity staging is based mostly on scales that have been developed in the past and in most cases have been used without either validation through historical analysis or the consistent training of maturity readers.
The assessment and management
of fish populations currently rely on estimations of the spawning Stock Biomass
(SSB), i.e on the
part of the population that contribute to the next generation, which is in turn based
on the proportion of mature fish within age classes in the population (i.e.
maturity ogives). The
proper identification of mature individuals in a given population is thus a
crucial step for a precise estimation of SSB and ultimately for evaluating
the status of the stock and establishing harvest levels.
attempts have been previously made, in particular, a workshop was conducted for
hake and monkfish in 2007 (WKMSHM), where a five-stage common maturity scale
was outlined. The Workshop on Maturity
Staging of Cod, Whiting, Haddock and Saithe
meanwhile, conducted during the same year, focused on other species. During this
latter meeting, a six-stage common maturity scale was developed and four
illustrated manuals were initiated.