An iconic Vineyard shellfish recovers in force
Well, would you believe it? After ten years of succumbing to the parasite Perkinsus marinus (aka ‘dermo’), a southern disease totally harmless to humans, oysters are finally fighting back in Tisbury Great Pond.
I had heard the rumors, seen the oyster-seed covered pieces of shell, rock, and seaweed, like little bits of evidence brought to us periodically since the beginning of August by Chilmark shellfish constable, Isaiah Scheffer. But until one morning in September, cooped up in the Hatchery all day, I had not had time to go look for myself.
So on this beautiful morning, I put on my rubber boots and went to walk the shore at Sepiessa landing in West Tisbury. The pond was high due to the recent heavy rain so I had to go in almost to the top of my boots. I saw a nice piece of shell under the surface and reached in to grab it.
There they were, oyster juveniles by the dozens, like little flat pearls with brown striping. I reached for second piece of shell and counted another 60 baby oysters, then reached for a rock, a less likely collector— it was loaded too.
“Biblical” had said Rick Karney. In his 33 years at the head of the Martha’s Vineyard Shellfish Group, it was by far the best oyster set he’d ever seen.
Oysters live the first two weeks of their lives as larvae, swimming in the plankton, then go through metamorphosis and “set” or cement themselves on an appropriate surface. After setting, oysters remain sedentary. They are not equipped to dig like clams or to swim away like scallops. If they cannot find the right substrate to set on (i.e. shell or other hard substrate), they do not survive. Years of infected adults and muddy bottoms had left the pond with some of its lowest numbers ever.
For the past 10 years, the Martha’s Vineyard Shellfish Group has attempted to jump start Tisbury Great Pond’s recovery with a technique called “remote set.” Large adult oysters from the infected pond, suspected resistant to the disease, were spawned at the Shellfish Hatchery in Vineyard Haven and their larvae set on scallop shells in tanks to optimize survival. The loaded pieces of shell were then seeded back into the struggling pond.
In the past two years, this effort was augmented greatly by the arrival of new funding from the Edey Foundation and the Menemsha Fisheries Development Fund. Artificial shell reefs were built on the bottom of the pond to create optimal conditions for the natural larvae to set and survive. It was a project dear to late Tom Osmers, former West Tisbury shellfish constable, who led the first round of reef building in 2009. This year, Isaiah, along with new West Tisbury shellfish constable Jeffrey Lynch, enrolled the entire West Tisbury fishing community and achieved in one day what last year took two and a half weeks. Together they raked, shoveled, toted, and loaded onto trucks, trailers, and boats, moving in eight hours more than 3 cubic yards of clam shell onto the bottom of the pond.
The quality of an oyster set depends on a lot of factors: broodstock fertility, water quality, rain, temperature, current, timing of the pond opening, and of course the presence of adequate substrate to set on. This year, the planets aligned. If you ask Isaiah if he thinks the amazing set is the result of the restoration efforts, he’ll smile and say, “Absolutely.”
Unfortunately, the oyster set also coincides with a phenomenal blue claw year. “The crabs are really chowing down on them,” said Isaiah holding a piece of shell already stripped of its oyster seed, “but even if one percent makes it, it will be plenty.”
And what does this mean for the years to come? Well, eight years ago, a similar oyster set in Edgartown Great Pond gave fishermen three great commercial seasons. Isaiah remembers fishing a few years after the set. “The whole entire pond was covered with oysters,” he said. The pond supported thirty-five commercial fishermen at three bushels a day for three months. “If Edgartown can be that good, I see the potential for West Tisbury.”
The new seed will, we hope, survive predation, grow, filter, thrive and in two years, reach legal size. If the fishery is managed properly and the restoration efforts continue, there could be more than three great oyster seasons. It could mean a complete recovery.