Spawning bed selection by the Baltic herring (Clupea harengus membras) in the Archipelago of SW Finland

Kaaria¨, J., Rajasilta, M., Kurkilahti, M., and Soikkeli, M. 1997. Spawning bed selection by the Baltic herring (Clupea harengus membras) in the Archipelago of SW Finland. - ICES Journal of Marine Science, 54: 917-923. The spawning bed characteristics of the Baltic herring (Clupea harengus membras L.) were investigated during the spawning season in the Airisto Inlet (Northern Baltic Sea) in SW Finland. Within the area, 46 transects were investigated by scuba diver; 37 transects were randomly selected and 9 were known to be spawning beds. Data on the substratum and vegetation were analysed by principal component analysis and discriminant analysis which revealed 10 parameters describing the spawning beds. Two groups were identified; the first contained most of the known spawning beds as well as those resembling them in many parameter values. These beds were situated near the deepest part of the area and contained broad and rich vegetation zones growing on hard bottoms. Herring eggs were not found on all of these beds, but analysis showed they were all potentially suitable for spawning. The other group consisted of sites with bottoms covered by soft sediments, even near the shore line, with the vegetation zone becoming narrower and poorer in plant species. Only two spawning beds were found in this group.