A standardized methodology ensures monitoring of long-term changes in species composition, species richness and size structure of coastal fish communities. For a selected suite of species, data on an individual level is collected for analyses of age structure, growth and year class strength.
Coastal fish communities in the Baltic Sea are mainly monitored using gill-nets, and Nordic multi mesh gill-nets are used as the standard gear since the early 2000s. Monitoring is usually undertaken in August when the species of a freshwater origin and those preferring higher water temperatures are most abundant at the coast. This includes species as perch, ruffe, pikeperch and species from the carp family (Cyprinidae). In some areas monitoring is carried out in the fall when water temperatures are lower and the segment of species preferring colder waters, as sculpins, cod, flounder, herring, whitefish and eelpout are hence larger.
At the west coast of Sweden monitoring of coastal fish communities is mainly undertaken using small paired fyke nets. Monitoring is carried out in shallow coastal waters during summer and fall, mainly targeting juvenile gadoids, wrasses, gobies and eel.
Descriptions of monitoring methods
The monitoring methods are described in Swedish in the following documents, that are designed using the standards of the Swedish Agency for Water management:
Metodbeskrivning för provfiske med yngelnot riktat mot sik (description af the method used when fishing with fry seine)
For additional information see Metoder för övervakning av kustfiskbestånd, Kustrapport 1996:3 . And for an English description see HELCOM website.
Protocols to be used in the field (swedish)
Yngelnot (fry seine protocol)
Gear specification (Swedish)