At the Cape Shore Laboratory, the Tide Sets the Lesson
With a nor’easter approaching, Rutgers students experience oyster research shaped by the rhythms of Delaware Bay
The first lesson at Cape Shore Laboratory began with the road in.
With a nor’easter approaching, Rutgers marine scientist Dave Bushek warned the access road to the Cape May Courthouse facility might flood between 8 and 9 a.m. Arriving at 10 a.m. and leaving by 3 p.m. would give the class a window of opportunity.
At this remote, 99-year-old Delaware Bay station, Rutgers researchers are testing genetic tools that could halve the time needed to select oysters for breeding. They also are raising bay scallops, laying the groundwork for a breeding program that could give New Jersey’s shellfish farmers another crop. New Jersey’s oyster and clam farms generated nearly $12 million in sales in 2023. The work promises new possibilities for an industry whose daily rhythms still depend on the tide.
The tide was running 2 to 3 feet higher than normal.
“The students can see how the wind and tides shape everything we do here,” Bushek said.
On a Friday in late September, a dozen Rutgers undergraduates arrived at the Delaware Bay station to help breed better oysters. An honors seminar led by Bushek and fellow professor Peter Oudemans was taking them to research stations throughout New Jersey.
The weather already had revised the itinerary.
At low tide, the bay retreats nearly a thousand or more feet exposing flats where researchers and neighboring oyster farmers collect bags of shellfish. That day, a storm surge held the water high.
“So instead of it being dry, you’ve got two and a half feet of water to walk through,” Bushek told the class.
The farm walk along the mudflats was off. Staff waded out the previous day to retrieve oysters. Sam Ratcliff, Cape Shore’s operations manager and a doctoral candidate, made room in the hatchery for activities planned outdoors.
First, though, he led the class on a brisk walk along the shore. Wind swept off the bay as he pointed toward the submerged oyster farm.
“Under that water are racks holding bags of oysters,” he told the students. “We put different breeding lines out there to see how they grow and how many survive.”
The bay feeds the oysters and tests them. Water flows through the mesh, carrying algae. Changing temperatures and two destructive diseases, MSX and dermo, help reveal which breeding lines are the hardiest.
“We follow them for about three years,” Ratcliff said. “The ones that do well can become the parents of the next generation.”
Ishika Bhagat, a senior majoring in cell biology and neuroscience, took in the lesson quietly. She had expected to see tanks and equipment, not a living laboratory.
“I was curious to see how concepts I learned in the science courses I took at Rutgers were applied outside the lecture hall,” she said. “But what I’m seeing is how research is really practiced day to day.”
Rain began lashing the class from the side. Inside, there were oysters to be counted, weighed and measured.
“This is pretty interesting, I’m not going to lie,” said Kyle Yoon, a mechanical engineering major, as he headed indoors.
The students were joining a breeding program begun in 1960 by Rutgers scientist Harold Haskin. His students called him “Hurricane Hal” for expecting fieldwork to continue in foul weather, Bushek said.
The program seeks to develop oysters that resist disease, grow well and have appealing, easy-to-open shells. Selected adults go to hatcheries to produce young oysters called seed, which farmers raise to market size.
The team has also successfully raised bay scallop larvae for three consecutive seasons. Ratcliff hopes that work will become the foundation of a breeding program, helping farmers expand the kinds of shellfish they cultivate.
Oudemans, who oversees Rutgers’ agricultural field stations, sensed the students were grappling with the concept of an experiment in the ocean being called a farm. He offered an analogy.
“Think of how hunting is different from farming,” he said. “Think of aquaculture as aquatic farming.”
Bushek, who oversees Rutgers’ marine field stations, further deepened the discussion, asking the students to imagine raising fish.
“When would the farmer own those fish? When he catches them?”
“I mean, I guess all the time,” said Joanna Paulraj, a senior majoring in biological sciences. “So maybe since the beginning, I don’t know.”
“You’re exactly right,” Bushek said.
He turned to one of Oudemans’ research subjects: blueberries and cranberries. Those crops belonged to the farmer as they grew. So did oysters, even when their growing grounds disappeared beneath the tide.
Could someone with a shellfish license simply collect a grower’s oysters?
“No, you can’t, because that’d be like going to somebody’s cornfield and harvesting their corn,” Bushek said.
The day’s experiment involved an innovation that changed oyster farming worldwide.
Most oysters have two sets of chromosomes, the structures that carry DNA. Rutgers researchers developed oysters with four. Crossing the two produces triploids, with three sets of chromosomes. Triploids can’t reproduce so they devote more energy to growth, reaching market size sooner.
“This technology that we developed here has been utilized globally,” Ratcliff said.
Jillian Jamieson, a laboratory researcher and doctoral candidate, studies oysters with four sets of chromosomes. They can lose chromosomes over time, developing a mixture of cells with different numbers of chromosome sets.
“So, I want to know why that happens and the rate at which it happens,” she told the students.
Breaking up into teams, students counted oysters to divide among bags at equal densities. Another measured 100 oysters for size and weight. A third prepared tissue samples for Jamieson’s analysis.
Even choosing an oyster requires care. Bushek asked whether one in the center of a crowded bag got as much food as one near the outside. Size could reflect inheritance or access to food.
“So, it could be environment,” he said. “Could very well be genes, though.”
Picking only the biggest oysters would introduce bias. Students needed to preserve the range of sizes, shapes and colors.
Bhagat found herself looking more closely.
“I was surprised by how much variation there was among oysters in one bag,” she said. “I was able to notice differences I would have overlooked before.”
To complete the exercise, Jamieson analyzed the tissue samples with a flow cytometer, measuring DNA content to check whether the oysters carried two, three or four sets of chromosomes.
Selecting oysters for breeding, however, can take years. Winter ice can kill them before researchers finish evaluating them. Ratcliff described using genetic information to identify promising parents sooner, potentially shortening a three-year evaluation to a year or a year and a half.
Bhagat saw a larger purpose in the day’s small tasks.
“My favorite part was sorting, weighing and measuring the oysters because it gave me a better understanding of how research begins with careful observation,” she said.
Watching the class, Oudemans said, “There’s just so much depth in the world around you that you don’t recognize, and for our students, this class offers them an opportunity to experience it.”
Explore more of the ways Rutgers research is shaping the future.
