Upvote:6
The Sea of Azov is counted as the world's most shallow "sea", with an average depth of only 7 meters (and a max of 14). Russia's battleships at that time had a draft of about 9m, and its cruisers a bit over 6. That made it impractical for all but the most careful of capital-ship naval operation. Submarine warfare without the ability to dive to escape trouble is obviously inadvisable as well.
This is probably why the actual Russian flotilla there consisted of small gunboats.
Also, its small size (max length 220 miles, max width 110) meant it could easily be searched by a small flight of aircraft. Typical aircraft search patterns of the era assumed a nominal search range of 25 miles, with ranges of 400-1000 miles. This means a single search two or three planes wide is quite likely to spot everything on that sea.
This was an era when air power was so dominant that naval units being so discovered without any defensive air power of their own could not expect any significant further operational lifetime.
So yeah, it would have been quite doable with aircraft alone, assuming said power had air superiority over that entire body of water.