NWWG assesses the stock status (recruitment, stock size, spawning stock size, and fishing mortality) of some of the demersal fish stocks (cod, haddock, saithe, and Greenland halibut) found in the areas around Greenland, Iceland, and the Faroe Islands as well as two pelagic fish stocks in Icelandic waters (summer spawning herring and capelin). In addition, both demersal and pelagic stocks of redfish are assessed, with some of these stocks being found in the Irminger Sea south of Iceland and Greenland.
The group employs a number of stock assessment methods, which reflect the amount of data available. The demersal fish stocks are normally well sampled (data-rich stocks) and are mostly assessed through age-based models, which in turn are based on time-series of age-disaggregated catch in numbers and catch per unit effort (CPUE) from one or several fishing fleets. Greenland halibut and redfish, however, are mostly assessed using methods based on CPUE-series, since there is less information about age for these species. The pelagic stocks occupy an intermediate position.
Although the main goal of NWWG's work is to provide a foundation upon which advice can be given to fisheries managers, the group also collates a wealth of information which can be used for other purposes. For example, the time-series of recruitment, stock size, and spawning stock size for the studied species can be compared with environmental variables or similar assessments in other areas.
The NWWG report itself is structured in such a way that the assessments are presented first, while additional information (e.g., how data are gathered, the ANNEX, and working documents) follows later.
The group consists of more than 20 experts from the Nordic countries, Russia, and Germany, among others.
NWWG meeting at ICES in Copenhagen in May 2013.