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 provided to assessment working groups, WGSINS also discusses and promotes the standardization and quality assurance of sampling gears and applied methods. This includes the review and update of relevant survey manuals, the correct species identification of eggs and larvae, and the preparation of data for archiving in the ICES Eggs & Larvae database.
The surveys coordinated by WGSINS cover the following areas and surveys:
North Sea:
- International Herring Larvae Surveys in the North Sea (IHLS)
- North Sea Midwater Ring Net Survey (MIK) targeting larger herring larvae
- Downs Recruitment Survey (DRS) targeting larger herring larvae
Irish Sea:
- Northern Irish Northeastern Larvae Survey (NINEL)
- Northern Ireland MIK Survey (NI-MIK) targeting different gadoids
Baltic Sea:
- Rügen Herring Larvae Surveys (RHLS)
- Baltic Ichthyoplankton Surveys (BIS) targeting Baltic cod, sprat and herring
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.
