December into April is the season when wild Atlantic sea scallops can be pulled from state-regulated waters in the Gulf of Maine both by divers and mechanical drags for our dining delight. Maine scallops are both delicious and pricey, but few of us realize that half of the scallop is chucked out at sea even though it’s perfectly edible.

Growing interest in farming scallops and developing food safety protocols hold out the promise that Mainers one day could eat more of the mollusk.

First, though, it’s important to understand why most Americans now eat only the scallops adductor muscle. Why don’t we eat the roe (also known as the coral), which Europeans, Asians and Australians all consider a matter of course?

“This is madness,” British celebrity chef Hugh Fearnley-Whittingstall writes in his “River Cottage Fish Book” of its disposal. “Plump and orange and rude with health, the coral is delicious – in fact, with its lightly granular, roelike texture, it is complementary to the white muscle meat. The two should be cooked together, still attached.”

Moreover, a market for roe-on scallops would give local fishermen the chance to serve up twice as much seafood with no additional impact on the marine ecosystem. So why isn’t there one?

Blame biology in part. Some parts of the Atlantic sea scallop, aka placopecten magellanicus, hold onto hazardous biotoxins the animal is exposed to when it encounters harmful algal blooms (think red tide), explains Dana Morse, a scientist with Maine Sea Grant and the University of Maine Cooperative Extension. The white adductor muscle most commonly recognized as a scallop on American menus is typically free of known biotoxins so is almost always deemed safe to eat. But the remaining edible part of the scallop – a tongue-shaped sac of orange roe (egg) and/or white milt (sperm) that wraps around the abductor – may hold on to the toxins, making the roe and milt unsafe to eat.

Photo by Christine Burns Rudalevige Photo by Christine Burns Rudalevige

Domoic acid and saxitoxin are the two main toxins. The former has a scary list of frightening symptoms – nausea, vomiting, cramps, diarrhea, confusion, dizziness, headache, seizures, cardiac arrhythmia and short-term memory loss. The latter sounds even worse, from tingling lips, tongue, fingers and toes, to respiratory issues and the loss of motor control in the arms and legs.

Then there is the matter of biotransformation, says Kohl Kanrit, director of public health for the Maine Department of Marine Resources (DMR). That’s when an Atlantic scallop internally changes less toxic compounds it has ingested into more toxic ones. As far as scientists know, not all scallop species can pull this off. But Atlantic scallops can, so knowing when to test a scallop for harmful toxins becomes a tricky business.

Add to these internal issues, the fact that Atlantic scallops are very mobile mollusks, more so than their sedentary European cousins. They propel themselves through the water using their adductor muscles to open and close their shells. This mobility makes it impossible to know with any certainty whether wild, roaming scallops have been swimming in the vicinity of a dangerous algal bloom. Nor can fishermen afford to test every scallop, every time.

For all of these reasons, Kanrit says, state food safety organizations like the one she works for have for decades deemed the roe of wild scallops unsafe for human consumption.

And as they have been required to do since the 1970s, fishermen shuck their scallops on their boat while still at sea, and toss everything but the adductor muscle back into the water for scavenger birds and other sea creatures to enjoy.

But the prospect of eating roe-on farmed scallops could one day become a culinary reality in Maine. Scallops have been farmed here since 2012 using cages set on the bottom of the sea within designated aquaculture sites. Sea farmers are also experimenting with a husbandry technique employed widely in Japan in which sea scallops are pinned to vertical ropes suspended in the ocean water. Since these caged and roped scallops do not change their location, their exposure to toxic algal bloom is easy to determine. Under these tightly controlled conditions, the Maine DMR has agreed to consider allowing the sale of whole, farmed scallops in Maine. Massachusetts regulators already allow the sale of whole and roe-on scallops.

Last year, Morse secured a grant to help the fishermen figure out when and how often their scallops will need to be tested for toxins. Morse is working with two scallop growers from Stonington and Bigelow Laboratory for Oceanic Science in East Boothbay to establish affordable protocols fishermen could follow and to collect baseline data for the toxicity levels of the various parts of these farmed scallops.

Exactly when Maine diners may be able to eat roe-on farmed scallops isn’t known. Morse did say early test results are positive and chefs he’s talked with are excited by the prospect of cooking scallop roe – whether sautéed alongside scallop adductors; blended into compound butter to finish a seafood pan sauce; or dried, smoked or pickled to add a colorful saline note to other dishes.

“We’re excited to get this product to market,” Morse said. “But we’ve got to do all the legwork first so that growers, regulatory bodies, chefs and eaters alike are confident it’s a safe product to consume.”

In the meantime, take advantage of Maines’s wild scallop season to perfect your favorite scallop recipe, which will likely be fine with roe in tow. Or try my Broiled Miso Scallops with Radish, Carrot and Scallion Salad.

CHRISTINE BURNS RUDALEVIGE is a food writer, recipe developer and tester and cooking teacher in Brunswick and the author of “Green Plate Special,” a cookbook from Islandport based on these columns. She can be contacted at cburns1227@gmail.com.

BROILED MISO SCALLOPS WITH RADISH, CARROT AND SCALLION SALAD

This recipe works for both roe-on and roe-off scallops. Watermelon radishes, available at most winter farmers markets as they store well in cellars, make this salad very colorful. But a dozen bunched radishes will also yield the volume needed for this recipe.

Serves 4 as a main course

3 tablespoons mirin

1 1/2 tablespoons light soy sauce

1 tablespoon rice vinegar

1 teaspoon sesame oil

1 large daikon radish (about 6 inches long)

1 large watermelon radish

2 large carrots

3 scallions

1 tablespoon pickled ginger, thinly sliced into strips

1/2 cup white miso

Pinch of cayenne pepper

1 pound (20-30) fresh sea scallops

2 cups cooked rice for serving

To make the dressing, combine 1 tablespoon mirin, the soy sauce, vinegar and sesame oil in a medium bowl and set aside.

Wash the radishes, carrots and scallions well. Trim tops and bottoms from the radish and carrots. Cut each vegetable into matchstick sized pieces. A mandolin helps immensely with this process.

Separate the dark green parts of the scallions from the white bottoms. Mince the white parts and set aside to use in the scallop marinade. Cut the green tops into 2-inch lengths. Slice each section, lengthwise into matchstick sized strips. Add the radishes, carrots, scallions and pickled ginger to the bowl with the dressing. Toss well and set aside.

In a second bowl, whisk together the miso, remaining 2 tablespoons mirin, 1 tablespoon warm water and cayenne pepper. Add the scallops, toss to coat and marinate for 10 minutes. Set an oven rack as close as possible to the broiler. Preheat the broiler to high. Lay the scallops in a single layer on a metal baking sheet. Broil until lightly browned, without turning, 3 to 5 minutes.

Spread dressed salad onto a serving platter, top with broiled scallops and serve with hot white rice.

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