My favorite facts about the Chesapeake Bay involve oysters: They were once so plentiful they could filter all bay waters (estimated at 19 trillion gallons) in less than a week; oyster reefs were once so large they constituted navigational hazards; and the competition for oysters was so fierce and violent in the 19th century that the Maryland legislature established an Oyster Navy to keep tongers and dredgers from killing each other.

Of course, overharvesting, disease, pollution and habitat loss eventually devastated the Chesapeake oyster population. The big reefs were fished out by the 1920s. Five decades later, the industry collapsed, and recovery seemed like a lost cause. The prospect of starting over, by reintroducing millions of oysters to the bay and having them do their thing — one adult oyster can filter about 50 gallons of water a day — seemed like wishful thinking.

But, convinced they could improve the bay with oysters, scientists and environmentalists from government agencies and nonprofits got busy. They’ve been redeveloping oyster beds, reefs and sanctuaries for several years in what has been hailed as one of the largest oyster restoration projects in the world.

In 2019, the Maryland General Assembly expanded and made permanent five large sanctuaries over the veto of then-Gov. Larry Hogan, who actually said sanctuaries would be “bad for the bay.” Sparing wild oysters from commercial harvest could only be seen as “bad” by someone who appreciated neither the history nor the science and accepted the predictable complaints of overregulation from watermen.

Post-Reagan Republicans have revulsion to regulation in their DNA, and MAGA Republicans even more so. But, when it comes to most natural resources, we don’t have much choice but to make decisions, based on science, that serve the resource first and the commercial interest second. That’s keenly the case with wild (non-farmed) oysters. The priority is reestablishing them as natural purifiers of the bay, not as ingredients for a stew.

The Chesapeake Bay Foundation, the Annapolis-based Oyster Recovery Partnership and the National Oceanic and Atmospheric Administration have been working on reoysterization — that’s my word, just made it up — for years. Step by step, acre by acre, the hope is that enough oysters will survive and spawn, that the population will grow and that water quality will slowly improve.

“In the short term, the success of sanctuaries will be limited by disease and poor water quality,” the foundation states on its web site. “But sanctuaries will make important contributions to restoration if disease resistance evolves in wild oysters over time and is supported by management practices.”

Another clear benefit to the reoysterization of the Chesapeake is this: The reefs have become habitats for lots of other aquatic life.

To demonstrate that, the foundation, the Coastal Conservation Association and the Chesapeake Oyster Alliance sponsor an annual week-long fishing tournament, the Rod and Reef Slam. It started Saturday and ends Sunday.

Anglers must fish on oyster reefs. More than 100 of them appear on bay maps, including large, restored reefs in Harris Creek, the Little Choptank River and the Tred Avon. Prizes are awarded in three divisions — powerboat, kayak and youth — not for the biggest fish, but for the greatest variety.

In 2021, Herb Floyd won the tournament with 13 species, and he provided me with the list: summer flounder, white perch, spot, toadfish, black sea bass, rockfish, spotted sea trout, weakfish (or gray trout), croaker, pigfish, pumpkinseed sunfish, bluegill and green sunfish.

I’d never heard of a pigfish.

“They call them grunt,” Floyd said, and there’s a reason for that. I looked it up. Pigfish make a grunting sound and, when they’ve been hooked, who can blame them?

Floyd, who lives in Trappe, is competing again this year and, as of Wednesday, he’d caught, recorded and released 12 varieties of fish from oyster reefs. His list so far includes at least six species he had not recorded in 2021 — sand perch, kingfish, sea robin, northern puffer and cutlassfish.

Ronnie Kirin, who lives in Crownsville, entered the tournament’s kayak division. He hooked a small bluefish and a channel catfish on an oyster reef. About midway through the tournament, he had recorded six species and was headed back out in hopes of adding to his list.

“We have seen sheepshead in this tournament, we’ve seen black drum,” says Allison Colden, the foundation’s Maryland executive director. “We’ve seen some of these really important, reef-associated species that have become more and more rare as we’ve lost oyster reefs over time. What we’re seeing, as we bring these oyster reefs back, is that the fish are coming back as well. Sheepshead, for example, are very dependent upon and very associated with oyster reefs, and for the longest time, they were extremely rare in the bay. Now we’re starting to see them come back.”

It should be noted that the Chesapeake had a pretty good year. In July, it received a C-plus for its ecological health from the University of Maryland Center for Environmental Science. That might not sound great, but it’s the bay’s best grade in two decades of annual report cards.

Maybe it’s too early to credit oysters with the improved grade. But in time, with good management and good luck, they’re bound to have a significant impact on the bay’s health, as their ancestors did, once upon a time.

The view, just after sunrise on Tuesday, to the east from Bay Ridge, Anne Arundel County, across the Chesapeake Bay to Kent Island.