The surveys provide long-term monitoring data on egg and larvae abundances which are utilized to produce fishery-independent estimates of spawning stock biomass and recruitment. In order to assure the quality of the survey time series to assessment working groups, WGSINS also discusses and promotes the standardization and quality assurance of sampling gears and applied methods, including the review and update of relevant surveys manuals, the correct species identification of eggs and larvae as well as the preparation of data for archiving in the ICES Eggs & Larvae database.
The surveys coordinated by WGSINS include the International herring larvae surveys in the North Sea (IHLS), the North Sea Midwater Ring Net herring larvae survey conducted at night-time during the Q1 IBTS (MIK), the Downs recruitment survey for herring larvae (DRS), the Northern Irish Northeastern Larvae survey (NINEL), the Northern Ireland MIK Survey targeting different gadoids (NI-MIK), the Rügen herring larvae survey (RHLS) and the Baltic Ichthyoplankton Surveys (BIS). In addition, the group provides a forum to discuss pilot surveys targeting eggs and larvae of other species and stocks.
Furthermore, the group aims to identify additional objectives that can be achieved within the existing survey designs and which can provide valuable data, e.g. in relation to the ecosystem approach to fisheries management. This includes collecting and archiving information on co-occurring eggs and larvae to establish time-series of non-target species as well as information on jellyfish, marine litter etc. By way of example, these data can provide a basis for further analyses of species distributions, the location and variability in spawning and nursery areas as well as the occurrence and quantification of jellyfish and marine litter.
