IMIS

This dataset contains herring monitoring projects that have been carried out in the Archipelago Sea area, and especially at the vicinity of the City of Turku, where one of the major herring reproductive areas is situated. The data are based on field sampling of the spawning fish, and direct monitoring of the spawning beds by scuba diving. During this three-decade biological survey, the environmental conditions of the spawning area have changed considerably, e.g due to eutrophication and decreasing salinity of the Baltic Sea. The monitoring campaigns started in 1984 fishin with a trawlor a trapnet and measurements of the fish length (cm), weight (g), sex, age, gonad stage (I-VII), gonad weight (g), mesentric fat (1-4), muscle lipid content (%), fatty acid composition (%), stomach content and ovary fat content (%) were taken.