On the Magothy River people are diving for oysters — not to fry, bake or slurp, but to monitor the health of the river's five oyster reefs.
On Sunday morning, Dick Carey, the leader of the all-volunteer dive team for the Magothy River Association, watched the water above the Dobbins Hill reef, located near Dobbins Island.
Two heads, complete with goggles and masks, appeared from beneath the waves. The divers hadn’t found anything.
Scott Hagedorn went down next. He sat on the edge of a boat in scuba diving gear, leaned back, and fell in.
About 18 minutes later Hagedorn surfaced with a cluster of oysters in hand.
“I scoured the whole damn bottom for that,” Hagedorn said.
More were brought onto the boat to be measured and checked for spat and dead oysters.
It’s hard to see in the water — the visibility below was about eight inches, one of the divers said Sunday. The volunteers who dive for the river association are specifically trained in how to work in low-visibility conditions.
“It can go from essentially no visibility, all the way up to maybe two feet,” Carey said.
One of the divers Sunday said they would love to actually see the river become clear again — they felt like volunteering on the team is a chance to reach that goal.
A lot of the work is done by feel, Hagedorn said. Hagedorn, who lives in Montgomery County, said he volunteers for the program because it is a reasonable effort to re-establish an ecosystem that’s having difficulty surviving.
“The Magothy River suffers from a lot of pollution issues just like any place else along the Chesapeake,” Hagedorn said.
Paul Spadaro, president of the Magothy River Association, said the volunteer oyster diving team has been in place since 2001.
Using a 1/3-meter quadrant, the volunteer divers take samples and extrapolate the approximate number of oysters on each reef. The oysters are also measured, as is the water quality at each reef.
Sunday’s count revealed a rate of 9,000 oysters-per-acre, Spadaro said. The reef is roughly three acres.
That’s a pretty low number, Spadaro said.
In the mid-19th century oysters at another reef, Rock Point, were so plentiful they formed an island of oysters, Spadaro said. Over harvesting damaged that population.
“The reality is we ate the oysters,” Spadaro said.
The Magothy doesn't have a strong showing for oyster spawning, Spadaro said. According to the National Oceanic and Atmospheric Administration, oyster spawning is salinity-dependent, and less common when salinity dips below 10 psu.
Sunday in the Magothy the water near the Dobbin’s Hill reef site was about 8 psu.
“Finding spat above the Bay Bridge is like the holy grail,” he said. “Development has pushed the salt water wedge to the south.”
The river has five oyster reefs at Chest Neck Point, Rock Point, Ulmstead Point, Dobbin Hill and Persimmon Point.
The divers make four or five trips a year and check each reef probably once every two years, Spadaro said, and also help with maintenance at the sites — this Sunday they will reattach a marker that indicates where one of reefs is located. Spadaro said they mark the reefs because they’re good habitat and a good resource for recreational fishermen.
One of the big takeaways from 16 years of oyster diving has been that there is an initial shock period for the oysters that are placed in reefs on the Magothy, Spadaro said. About half of the oysters die off within the first few months of placement — but that’s not the only thing they’ve learned.
“Once you get over that initial shock and the oysters survive a year or two, they will survive five to 10 years,” Spadaro said.
Oyster diseases are absent in the Magothy, Spadaro said — that gives the Magothy oysters an edge.
The diving program is self-supporting, Spadaro said. The divers volunteer and bring their own equipment.
In addition to measuring the oysters present at the reef, Spadaro said the divers will also double-check the marked edges of each reef, to ensure when additional spat is added that it is truly going onto other oyster shells, not into the mud.
In 2004 a large number of dark false mussels contributed to clearer water in the river — evidence that filter feeders could effectively clean the river, Spadaro said.
But it will take more than hanging oyster cages off docks — Spadaro said they have calculated that it would take 75 cages hanging from every piling in the river to clean the water.
What separates the Magothy’s diving program from others is the people, Spadaro said.
“We’re consistent, and this is our home,” Spadaro said.
For the group’s leader, 80-year-old Carey, diving is a passion. Carey was leading the group, but didn’t dive Sunday.
The dive team has also shrunk over the years, from roughly 45 volunteers to about 20, Carey said. Spadaro said they are seeking new divers, and also looking for leader to take over for Carey when he steps down.
Many of the same volunteers return year after year to dive on the oyster reefs, like Hagedorn, who has been with the group since the beginning. He sees neat stuff while diving, such as rays feeding on the oysters and rockfish, he said.
“It’s fun to go down there and see what’s happening,” he said.