I haven't found that date for 8 Soviet ship losses in [uboat.net] , but 28. Aug 1941 - 6 destroyers and 2 subs, all lost to mines in the baltic sea. The soviet forces tried to evacuate Talinn after the german attack. It looks like the axis forces laid dense minefields and the soviet fleet wasn't able to minesweep the only possible evacuation route to Kronstadt.