Somewhere in the vast Chesapeake Bay, there’s a fishing spot known as Ed’s Lump. It is believed to be the remnants of a giant oyster reef, rising from deep water to within 24 feet of the surface.

To leave the ocean, which has been his backyard his entire life, Pennisi is giving up a multi-generational trade that was once the backbone of the Bay Area economy, when small fishing boats dotted ...