Are you sure it's not just better detection?  In 1900, we'd never know about Epsilon unless a ship sailed through it and lived to tell the tale.  With no satellites, we had no way of knowing about hurricanes that didn't hit us.
There were more ships at sea in 1900.  Of course tonnage is vastly greater today, with some supermax ships up to 300,000 tons, as opposed to the 3000 ton freighter of the past.  But the seas have been well covered for a long time.  The trend is real, not just sampling error.