Most of the naval action in the Baltic up until 1944 was mainly concerned with the laying of defensive minefields by both the Germans and the Finns in the eastern part of the Baltic Sea.
For further information about the above my I recommend that you try and get hold of the following book "German Destroyers of World War Two", by M J Whitley. This gives invaluable information with regard to the naval war in the Baltic that was carried out by German destroyers and torpedo boats from 1941 - 1944.
Also, I can recommend the following for additional information about operations in the Eastern Baltic, "German Coastal Forces in World War II" and "German Cruisers of World War II", also by M J Whitley.
Mines caused anyway huge damage to the Baltic fleet, sinking several destroyers, damaging more destroyers and cruisers (as did Finnish coastal defences during Winter War) and destroying a heap of subs and light units. Also many German ones were victims, as well as the armoured coastal battleship, Finnish flagship Ilmarinen.